C H A P T E R O N E

Atmosphere

Contents Part 1Environmental Conditions and Trends

AtmosphereKey Issues 1.2

Introduction 1.3

Structure of the Atmosphere 1.3

Climate 1.4

Introduction 1.4

Natural variability 1.6

Human-induced change 1.9

Future climate changes 1.15

Air Quality 1.18

Condition of the atmosphere 1.18

Pollution sources 1.20

Responses to poor air quality 1.24

Indoor air 1.24

Conclusions 1.26

Contributors 1.26

References 1.27

CASE STUDIES PAGE

1: Cape Grim Baseline Air Pollution Station 1.9

2: Ozone and UV-B radiation in Hobart 1.14

3: Lutana heavy metals contamination 1.19

4: Air quality studies: Launceston, Hobart

and Tamar Valley 1.22

5: Smog Busters 1.23

LandKey Issues 2.2

Introduction 2.5

Geodiversity 2.5

Description 2.6

Geoheritage features 2.7

Knowledge of geoheritage 2.8

Condition 2.10

Indicators of geoconservation status 2.11

Soil 2.14

Description 2.14

Condition 2.14

Vegetation 2.22

Description 2.22

Condition 2.22

Pressures 2.28

Weeds, Pests and Diseases 2.34

Weeds 2.34

Pests and diseases 2.35

Fire 2.37

Fire incidence 2.37

Fire management 2.38

Background to the State of the Environment report

Sustainable development in Tasmania i

Preparation of State of the Environment reports i

Aims of the first report i

Structure of the report ii

The process ii

Environmental information iii

Improving the reporting process iv

Geological Time Scale iv

Setting the Scene page

CASE STUDIES PAGE

1: Rehabilitation of Exit Cave 2.12

2: Peatlands and fire 2.13

3: Eucalyptus rubida—a species threatened by

land clearance 2.31

4: Ellesmere remnant vegetation management 2.32

5: Central Midlands Drought Landcare Project 2.32

6: West Coast Weeds Strategy 2.34

7: Tamar Valley Weed Strategy 2.35

8: Feral goats in Tasmania 2.36

9: Landscape values in Cataract Gorge Reserve 2.46

ATMOSPHERE 1.2

Key IssuesGlobal• Understanding the atmosphere, past and present, is

critical to being able to predict climate patterns, andfuture climate changes. Better climate models result inbetter climate predictions for droughts, enhancedgreenhouse effect, El Niño and Southern Oscillationetc.

• The atmosphere is extremely complex, affected by amultitude of variables. Long-term, systematic datasetsare essential to gain the necessary understanding of thesystem.

• Understanding the Antarctic climate system is crucialto understanding the atmosphere of the southernhemisphere.

• Good models allow for the determination of the effectsof climate changes, not just on meteorological features(e.g. rainfall, temperature), but also on biological andeconomic features (e.g. agriculture, species’ distribu-tions, biodiversity implications, planning and theprovisioning of services).

• The State and Commonwealth have responsibilities tovarious international treaties. However, the informa-tion required to accurately report on these is oftenlacking (e.g. rate of emissions of greenhouse gases andozone-depleting substances). Monitoring and action isrequired to meet the obligations.

• Tasmania can be severely affected by global problemssuch as ozone depletion and an enhanced greenhouseeffect, so needs to be an active member in reducingemission that cause such problems.

Local• To assist in maintaining its ‘clean-green’ status,

Tasmania requires air quality that is better thanelsewhere.

• Cape Grim Baseline Air Pollution Station providesexcellent baseline information, but little is knownabout the air quality conditions in the rest of the State.

• The dispersion of pollution is critical at a local level.The few studies that have been done highlight howmuch more work is needed to understand how pollu-tion is dispersed in Tasmania, and what planningrequirements are necessary to lessen detrimental healtheffects.

• Studies have indicated that the worst pollution is inareas where most people spend most of their time—inurban areas, around industrial sites and inside build-ings. The health effects of this have not been fullydetermined.

• Many Tasmanians are unaware of the important cli-mate research establishments in the State, such as theCape Grim Baseline Air Pollution Station, Antarcticand Southern Ocean Cooperative Research Centre,University of Tasmania and CSIRO Division ofOceanography.

Response• The education of the community in air quality, particu-

larly indoor air quality, and climate change issues isessential.

• Monitoring programs have not been maintained overrecent years. Increased understanding of the healtheffects of pollutants should be leading to the establish-ment of rigorous monitoring programs to ensurepollutant levels do not reach harmful levels.

• A review of the significant air quality pollutants inTasmania would encourage further research into theireffects and enable monitoring programs to be priori-tised.

• Planning for climate change under an enhanced green-house effect will reduce the cost and severity of futureproblems, particularly in the coastal zone.

IntroductionThe atmosphere is a very thin and fragile skin around theearth. It consists of gaseous particles, held in place by theearth’s gravity, that form the air on which life depends.

The atmosphere is constantly changing. Daily weather pat-terns are the most obvious examples of change, butprevious temperature changes over millions of years, result-ing in a number of glacial periods, have left a variety oflegacies in the Tasmanian landscape (such as sharp moun-tain ranges, cirques, moraines and many lakes).

The composition of the atmosphere has also evolved overbillions of years. It is believed that the atmosphere oncecontained high levels of poisonous gases such as sulfurdioxide, ammonia and hydrogen sulfide. Oxygen onlybecame a significant component with the evolution ofalgae and other plants.

However, these changes in the atmosphere took place oververy long periods of time. Humans are now putting suchpressure on the atmosphere that changes are occurring at afaster rate than at any time in the past. The production ofatmospheric pollution since the Industrial Revolution,

depletion of the ozone layer and an enhanced greenhouseeffect are all issues that require attention. An importantway to prevent further degradation of the atmosphere is toincrease understanding of the nature of the atmosphere, itsstructural properties and potential areas of deterioration.Addressing such issues will help ensure a cleaner environ-ment for future generations.

Structure of theAtmosphereThe structure and composition of the atmosphere allow theearth to support life. But they did not always do so; billionsof years ago the atmosphere was extremely violent, andmade up primarily of water vapour, carbon dioxide, nitro-gen, hydrogen, sulfur dioxide, carbon monoxide,ammonia, methane, and hydrogen sulfide. These days,around 99% of the atmosphere near the earth’s surface ismade up of nitrogen and oxygen, with all the other gasesmaking up the last 1%. Some of these gases are reasonablyconstant, while others may vary considerably (Table 1).Much of the water vapour once found in the atmospherecondensed as the earth cooled billions of years ago, form-ing the seas and oceans that now cover 71% of the earth’ssurface. Most of the carbon dioxide has either dissolvedinto the oceans, been converted into such features as coaland limestone, or been incorporated into plants andanimals.

Over 70% of the mass of the atmosphere is in the loweratmosphere, the troposphere (Figure 1), which extends

ATMOSPHERE 1.3

TABLE 1: COMPOSITION OF AIR NEAR THEEARTH’S SURFACE

Gases Formula % by volume

Nitrogen N2 78.08

Oxygen O2 20.95

Argon Ar 0.93

Neon Ne 0.001 8

Helium He 0.000 5

Hydrogen H2 0.000 05

Xenon Xe 0.000 009

Carbon dioxide CO2 variable (average 0.036)

Methane CH4 variable (average 0.000 1)

Ozone O2 variable (polluted air aver-

age 0.000 004)

Carbon monoxide CO variable (polluted air aver-

age 0.000 02)

Sulfur dioxide SO2 variable (polluted air aver-

age 0.000 001)

Nitrogen dioxide NO2 variable (polluted air aver-

age 0.000 001)

Particles (dust etc.) variable (polluted air aver-

age 0.000 01)

Water vapour H2O variable (up to 4% in some

areas)

Source: adapted from CROWDER 1995

FIGURE 1: STRUCTURE OF THE ATMOSPHERE

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TropopauseTROPOSPHERE

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THERMOSPHERE

1

1000

0.001

0.000001

Ozonelayer

-120 -70 -20 30 80 130Temperature (°C)

Mt Everest8840 m

FIGURE 2: SOLAR RADIATION REACHING THE EARTH’S ATMOSPHERE

The radiation reaching the earth is made up of a wide

range of wavelengths. The visible light which we can

see makes up only a small component of the whole

spectrum.

Visiblelight

Ultra-violet

Nearinfrared

Farinfrared Microwaves TV waves Radio

waves

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Wavelength

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5

from the ground to between 11 and 15 km from the earth’ssurface. It is primarily within this layer that clouds occurand most of our weather takes place. The atmospherepeters out several hundred kilometres from the earth’s sur-face into interplanetary space, but the ‘skin’ it forms is thinwhen compared to the earth’s diameter of over 12 500 km.

The ozone layer, which protects the earth’s surface fromharmful solar radiation, is mainly concentrated between 15and 30 km above the earth’s surface within the strato-sphere. Absorption of ultraviolet radiation (Figure 2) byozone in this layer causes the temperature to rise. Theabsorption of shorter wavelengths of ultraviolet radiationby oxygen molecules in the thermosphere causes the tem-perature to rise there too. Above the thermosphere, the lackof any air means that temperature has little meaning.

ClimateIntroductionThe climate of the earth is driven by the sun. Differences inheating at the poles and the equator, and between land andsea, create winds, which transfer energy around the globe(Figure 3).

The climate of Tasmania is largely determined by itsposition at the northern edge of the band of westerly winds

ATMOSPHERE 1.4

FIGURE 3: GLOBAL AIR CIRCULATION

Winds circulate anticlockwise around the high-pressure systems,

and clockwise around the low-pressure systems, transferring

energy around the globe.

SUBTROPICAL HIGH PRESSURE BELT

HIGH PRESSURE BELT

LOW LOW

LOW LOWWesterlies

Westerlies

NETrades

Equator

SE Trades

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MAP 1: AVERAGE MAXIMUMTEMPERATURE ANDRAINFALL PROFILES FORVARIOUS SITES AROUNDTASMANIA

Source: BUREAU OF METEOROLOGY 1988

known as the Roaring Forties. However, the continentallandmass of mainland Australia to the north also has asignificant influence. Cold air from the Southern Oceancan bring freezing winds and snow to the State, while airheated over the Australian mainland can result in hot, drywinds.

Nowhere in Tasmania is further than 115 km from thecoast, and the surrounding ocean moderates the island’sclimate. Thus, the climate is classed as temperate maritime.Generally, summers are mild and winters cool to cold(Map 1).

The coldest temperature recorded by the Bureau ofMeteorology in Tasmania (-13.0°C) was at Shannon,Tarraleah and Butlers Gorge on 30 June 1983, while thehighest temperature was 40.8°C at Bushy Park on26 December 1945, and at the Hobart Regional Office on4 January 1976 (Bureau of Meteorology 1993).

Air flow over the State is generally from the west, whichresults in cloudy and wet conditions in the south and west.Snow is possible at all times of the year, though more likelyin winter. The north and east are normally much drierunder these conditions.

However, low- and high-pressure systems (cyclonic andanticyclonic systems) embedded in the flow can change thewinds, providing a variety of weather conditions. Easterlywinds usually result in wet conditions through the east,and finer conditions in the west. These are more commonduring spring and summer. Northerly airflow can occur

during the summer months, and produces hot, dry windsover much of the State.

During spring in particular, northerly winds are sometimesassociated with low-pressure systems approaching theState. These winds can bring heavy rains to the north, oftencausing flooding in rivers such as the Mersey, Forth andNorth and South Esk rivers.

Variations in topography (mountains, hills and valleys)also affect wind direction. For example, Hobart andLaunceston rarely experience pure westerly winds, as theDerwent and Tamar valleys respectively change the wind’sdirection (Figure 4). Understanding the surface wind pat-tern is important for determining the dispersion patternsof, for example, factory emissions, vehicle exhaust and agri-cultural sprays, and the effect of windbreaks onevaporation rates over agricultural areas.

The topography also modifies other aspects of the climate,especially temperature and precipitation. The prevailingwesterly airflow from the Southern Ocean is generallymoisture-laden. When it is forced to rise over the western,central and southern highlands, it cools and releases muchof its moisture as rain (and snow). This pattern occursthroughout the year, resulting in high precipitation levels,but is more pronounced during winter and early spring.By the time the air flow gets to the eastern side of the State,it has released most of its moisture, and the chance of rainis reduced (Figure 5). Hence there is a marked difference inaverage cloudiness and rainfall across the State (Map 1);

ATMOSPHERE 1.5

FIGURE 4: WIND ROSES FOR HOBART AND LAUNCESTON

The Derwent and Tamar valleys channel the surface winds into north-westerlies. Source: BUREAU OF METEOROLOGY

FIGURE 5: RAINFALLACROSS TASMANIA

Moisture condenses into

clouds as moisture-laden

westerly winds rise and cool

over the Tasmanian

highlands. Little moisture is

left by the time the airflow

reaches the east coast.

Autumn Winter

Spring Summer

Autumn Winter

Spring Summer

HOBART LAUNCESTON

Windspeed (km/h)

≤10 11-20 21-30 >300

10%

some areas in the east receive an annual average of around500 mm, while parts of the west receive over 3000 mm.

At times, the east coast and adjacent ranges experienceheavy rainfall. Typically, this happens when a significantlow-pressure system is located in Bass Strait or the TasmanSea, and moisture-laden winds are forced to rise over theland.

The topography also has an important influence in sum-mer, especially during bushfires. The northerly sides of hillsreceive more sun, so tend to be drier than south-facingslopes. In addition, fires move much more quickly uphillthan they do downhill. When combined with the northerlywinds that are often experienced in summer, the result canbe a very fast spread of fire. These conditions were particu-larly evident during the 1967 bushfires (see also ‘Fire’,p. 2.37), when the spread of fires was extremely rapid.

The topography also affects temperature. Generally, tem-peratures drop about 1°C for every 100 m rise in altitude.However, this can vary at different sites and with the timeof day and year, causing features such as cold air drainageand frost hollows. Such features are particularly evidentduring still winter conditions. The lack of cloud at night,which is common when a high-pressure system passes overthe State, results in a net loss of radiation (heat) from theground, causing the ground to cool dramatically (Figure 6).The cold surface cools the air above it, so the coldest tem-peratures are closest to the ground.

Cold air is denser than warm air, so just like water, it flowsdownhill (i.e. cold air drainage) and pools in topographiclow spots (frost hollows), (Figure 7). Below the suddenchange in temperature (the inversion) the air is very stable,with the difference in air densities above and below theinversion reducing mixing in the air column. Hence theinversion acts as a lid, keeping any pollutants released intothe lower layer close to the surface. The pollution problemcan be increased when inversions occur in valleys, as

contaminants are fully contained by the valley sides andthe inversion above. Under such conditions, contaminantssuch as those from wood heaters, can become quite con-centrated.

Launceston and the northern and western suburbs ofHobart often experience inversions during the wintermonths, but they regularly occur throughout Tasmania.The amount of fog typically indicates the severity of theinversion.

Natural variabilityThe climate is not just variable across space (geographi-cally); it is also variable over time. There have beensignificant variations over the last million years (Figure 8),with alternation between lower temperatures (glacial peri-ods) and warmer times (interglacials). The changes arecaused by a complex interaction of many factors, butmainly by variations in the amount of solar radiation

ATMOSPHERE 1.6

FIGURE 7: COLD AIRDRAINAGE IN AVALLEY

As the ground cools at

night, it cools the air above

it. The dense cold air then

flows downhill into the

valley. Any pollution

released into this flow can

become quite concentrated

in lower areas.

FIGURE 6: TEMPERATURE INVERSION PROFILES

Changing temperature profiles between day and night

typical of clear winter nights. As the ground cools after

dark, it cools the air above it, creating a temperature

inversion.

Day Night

Temperature

Ele

vati

on

FIGURE 8: ESTIMATED AVERAGE GLOBALTEMPERATURE OVER THE LAST MILLION YEARS

Current average temperature is about 15°C.Source: FOLLAND ET AL. 1990

800 000

1000 AD

Years before present

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reaching the earth, which affects the amount of heating ofthe earth’s surface. Volcanic activity can affect the amountof radiation reaching the earth’s surface, because volcanicdust blocks out sunshine and causes temperatures to cool.

During the last glacial, which had its peak around 20 000years ago, average temperatures were probably only around5°C lower than present (Clark & Cook 1983). While thatmay not seem much, it was enough to leave most of theCentral Highlands covered by an icecap (Map 2). Manyother areas also had small icecaps and glaciers, or weresubject to periglacial processes such as freeze–thaw cycles.

With so much water locked up in ice and snow during theglacial periods, the level of the oceans was lower, and theatmosphere generally drier. Many of the sand dune com-plexes in the north-east were formed during this time,when the dry, sandy plains were blown around by the morefrequent and stronger winds. Plants and animals unable toadapt to such different climatic conditions survived insmall areas that still remained suitable (refugia), fromwhich most expanded their range again during the inter-glacial periods.

The earth’s climate has also varied over the last few hun-dred years. From the 15th to 18th centuries there was a‘little ice-age’, with average temperatures a little lower thaneither before or after. Most of the variation has occurred forreasons that are natural. However, there is evidence tosuggest that some of the climatic cycles are now beingmodified by emissions produced by humans.

The Southern Oscillation and El NiñoThe climatic phenomenon known as the SouthernOscillation has dramatic effects on Australia, particularlyon the agricultural sector (Bureau of Meteorology 1994).During the most extreme events, known as El Niño events,the Australian region experiences much drier conditions(Map 3), with droughts throughout most of the country(Map 4). Tasmania is at the edge of the area affected by the

ATMOSPHERE 1.7

MAP 3: AREAS MOSTCONSISTENTLYAFFECTED BY EL NIÑOEVENTS

Source: BUREAU OF METEOROLOGY 1994

MAP 4: EL NIÑO-RELATED DROUGHT AREAS INAUSTRALIA, 1951–1992

Source: BUREAU OF METEOROLOGY 1994

wet dry warm

Glacial

Known periglacial

Probable periglacial

March 1991 to January 1992 April 1982 to February 1983

March 1972 to January 1973 August 1968 to January 1970

January 1965 to November 1965 February 1951 to March 1952

MAP 2: GLACIATED AREAS

Generalised distribution of areas affected by glacial and

periglacial processes over the last million yearsSource: COLHOUN & HANNAN 1990

Southern Oscillation, but nevertheless experiences similarproblems to the rest of the east coast of mainlandAustralia.

The Southern Oscillation is a major air pressure shiftbetween the Asian and east Pacific regions, resulting inchanges to the circulation of air, known as the ‘Walker cir-culation’ (Figure 9). The Walker circulation is named afterSir Gilbert Walker, a Director-General of British observato-ries in India. Early this century, he identified a number ofrelationships between seasonal climate variations in theAsia and Pacific region.

The Humbolt Current brings cold water northward alongthe South American coast. It then moves to the east alongthe equator, where it is heated by the sun, raising the tem-perature by as much as 8°C. The air moving over thesewaters is warm and moist, and rises to high levels in theatmosphere. The rising air is associated with a region oflow pressure, towering cumulonimbus clouds and heavyrains. The air then travels eastward, cools, and sinks overthe eastern Pacific Ocean.

During the other extreme of this circulation pattern, knownas El Niño, the Walker circulation patterns weaken, and theseas around Australia cool. The trade winds slacken andfeed less moisture into the Australian/Asian region, result-ing in a high probability of drought in Australia.

However, the weaker East Australian Current means thatthe interface between the warmer waters and the colderAntarctic waters (the Sub-Tropical Convergence) movesnorthward into the Tasman Sea. The Sub-TropicalConvergence is a zone of high biological productivity,important for many commercial fisheries. For example,during El Niño events, jack mackerel become more abun-dant around Tasmania (see also ‘Ocean Currents’, p. 7.8).

El Niño episodes also affect people in other countries.Along the South American coast, off Ecuador and Peru,there is normally an upwelling of colder, nutrient-richwaters from the deeper ocean to the surface. El Niño (‘theboy child’ in Spanish—a reference to Christ) comes aroundChristmas. The upwelling weakens and warmer currentsspread along the coast, bringing rain to one of the driestcoastlines in the world. Nevertheless, for many people inPeru and Ecuador, El Niño episodes are not as welcome asthe name may suggest. The cold, nutrient-rich waters sup-port abundant plankton, which in turn support a largefishing industry. The warmer currents lack nutrients, andfish and other marine life die due to the lack of food.Severe El Niños can devastate the fishing industry in theregion.

The status of the Walker circulation pattern is measured bythe Southern Oscillation Index. It is calculated monthly,based on the difference in air pressure between Tahiti andDarwin. The long-term average of the Southern OscillationIndex is zero. When it is positive, the Walker circulation isat its strongest, and stronger Pacific trade winds andwarmer seas to the north of Australia mean that easternand northern Australia will probably have wetter than nor-mal conditions. The Southern Oscillation Index is stronglynegative during an El Niño episode, and the Walker circula-tion is at its weakest. The seas around Australia cool, thetrade winds slacken, and less moisture is fed into theAustralasian region, increasing the probability of droughtin Australia.Indicator theme: Status of the Southern Oscillation

Droughts in Tasmania are also affected by other factors of amore local nature. The intensity and exact location of high-and low-pressure systems have a significant impact on

ATMOSPHERE 1.8

FIGURE 10: THE GLOBALRADIATION BALANCE

Numbers refer to percentage of

incoming solar radiation.Source: adapted from CROWDER 1995

High pressuresystem

High pressuresystem

High

High

PacifcOcean

PacifcOcean

SouthAmerica

Australia

SouthAmerica

Australia

Surface winds

Cooler sea

THE WALKER CIRCULATION Verticalaircirculation

Trade winds

Warmer seaCooler sea

Warmer sea

a

b

FIGURE 9: THE WALKER CIRCULATION

a. The typical wind and water circulation pattern.

b. The circulation pattern during an El Niño event.Source: BUREAU OF METEOROLOGY 1994

Solar radiation(shortwave)

100

Longwave radiationemitted by earth

117

Longwave radiation(heat) from earth

6

Longwave radiationfrom atmosphere and

clouds64

96Longwave radiationabsorbed by earth

Latent heat23

51Absorbed by

earth

Reflected byearths surface

4

Reflected byclouds

20

Reflected byAtmosphere

6

Turbulence7

19Absorbed byatmosphereand clouds

Tasmanian rainfall. Lows passing to the south of the Statemay bring rain to the west and south, but often little to thenorth and east. Lows passing through Bass Strait can bringvery heavy rains to the north and east. Extended periodswith high-pressure ridges over the State tend to produceprotracted dry weather over the State as a whole.Indicator theme: Variation in rainfall compared with the long-term average

(% change)

Management of the environment in an ecologicallysustainable way relies on a sound understanding of the waythese many climatic factors interact. For example, beingable to predict how long a drought will last for makes itpossible to plan to avoid the worst problems. Managementstrategies can be modified to ensure that activities aresustainable.

Human-induced changeNot all changes in climate are natural. There is increasingevidence that changes are now occurring faster than in anyprevious natural cycle. In particular, average temperatureshave risen by 0.5°C in the last 30 years. The Intergovern-

mental Panel on Climate Change now believes thathumans are causing some of the changes to the earth’sclimate. Most critical is the production of chemicals thatenhance the greenhouse effect, and deplete the ozone layer.

Greenhouse effectNitrogen and oxygen, the main components of theatmosphere, are almost transparent to the shortwave solarradiation that reaches the earth from the sun. Much of thisradiation is absorbed by the land and oceans (i.e. they areheated), but a significant amount is reflected by clouds,snow and ice. The hydrological cycle (p. 3.3), and thebroad atmospheric and ocean circulation patterns help toredistribute the energy to areas receiving less shortwaveradiation. Energy is also radiated back from the earth aslongwave radiation (heat), maintaining the balance withthe incoming solar radiation (Figure 10).

Water vapour, carbon dioxide and many other gases absorbsome of the radiation reaching the earth from the sun, andmuch of the longwave infrared radiation emitted by theearth. This natural process known as the greenhouse effectstores heat in the atmosphere. Without it, the earth’s

ATMOSPHERE 1.9

CASE STUDY 1: CAPE GRIM BASELINEAIR POLLUTION STATION

Subtle but significant changes

in the atmosphere are becoming

apparent. For example, CO2

levels and average temperatures

have risen over the past 100 years.

The World Meteorological

Organisation started the Background

Air Pollution Monitoring Network in 1972. It

was designed to collect and test background, or

‘baseline’, air from sites around the world (Map 5). The

sites were in remote areas to minimise contamination

from local sources. The data from all these sites will help

scientists to better understand the earth’s atmosphere

and the changes caused by human activity.

Cape Grim in north-west Tasmania was chosen for

studying air in the southern hemisphere. Set up in 1976

on the Woolnorth property, the first laboratory was a

caravan donated by NASA. A permanent building that

was purpose-built soon after is now a highly

sophisticated facility providing essential data on the

southern hemisphere atmosphere.

The station is funded and managed by the Bureau of

Meteorology, which jointly supervises the scientific

program with the CSIRO Division of Atmospheric

Research. Monitoring of the highest quality is the goal.

Samples are regularly sent to other laboratories around

the world to ensure accuracy, as well as to participate in

a range of cooperative programs.

The air of most interest is that originating from the

Southern Ocean—the baseline air. Sampling equipment

is switched on if baseline conditions are experienced for

5 consecutive minutes, and are shut down if they are

non-baseline for longer than 1 minute. However, the

Station also conducts monitoring of non-baseline air.

Measurements are made of gases and particles in the air

(e.g. carbon dioxide, radon, aerosols), of solar radiation

(e.g. intensity, ultraviolet levels) and of meteorological

conditions (e.g. wind speed and direction, rainfall,

temperature, pressure).

The work conducted at Cape Grim is crucial to a greater

understanding of the nature and behaviour of the

atmosphere. It is the most sophisticated station in the

southern hemisphere, so is an important link in the

global network of monitoring stations that is helping to

explain changes in the atmosphere.Souce: HOLPER 1992

MAP 5: GLOBAL AIRPOLLUTION BASELINEMONITORING SITES

Source: PAUL HOLPER, CSIRO

average surface temperature would be about 33°C lowerthan at present (Lehane 1995). However, the level of green-house gases (e.g. carbon dioxide, methane, nitrous oxide,and the manufactured chlorofluorocarbons) are known tohave increased substantially in recent times, and areenhancing the greenhouse effect (see also Case Study 1).

Enhanced greenhouse effectWhile the greenhouse effect is a natural process, theenhancement of this process through human activities iscausing widespread concern. The implications of anenhanced greenhouse effect are difficult to quantify, butinclude more than just a simple rise in temperature. Therewould also be changes to average and seasonal rainfall, andan increase in the frequency and severity of extreme eventssuch as very hot weather, storms and storm surges.

The most significant greenhouse gases are water, carbondioxide, methane, nitrous oxide, ozone and chlorofluoro-carbons (CFCs). Water vapour contributes about 75% tothe natural greenhouse effect, but the input of vapour intothe atmosphere from human activity is so much smallerthan natural levels that it is usually disregarded.

However, any changes in the amount of water vapour inthe atmosphere as a result of the enhanced greenhouseeffect would affect the climate as a whole.

Carbon dioxide too is a natural greenhouse gas, butincreasing anthropogenic emissions have led to it becom-ing the most significant contributor to an enhancedgreenhouse effect. Carbon naturally cycles between theoceans, the atmosphere, the land and vegetation (Figure11). The increase in the use of fossil fuels since theIndustrial Revolution has increased the amount of carbonentering the atmospheric component of the cycle. Whilemuch of the carbon dioxide released by the power genera-tion and transport industries has been absorbed by avariety of ‘sinks’ (especially the oceans), it appears thatcarbon dioxide is still building up rapidly in theatmosphere (Figure 12).

Vegetation can also affect the amount of carbon dioxide inthe atmosphere—the seasonal pattern is evident in Figure12. Plants photosynthesise most during spring andsummer, taking up carbon dioxide from the atmosphere,but a lag in the system means that the drop in carbondioxide levels is at its greatest in autumn. There is also a

ATMOSPHERE 1.10

FIGURE 12: CONCENTRATION OF GREENHOUSE GASES

The level of greenhouse gases have been increasing dramatically. The levels are now well above pre-industrial times. The seasonal

cycle of carbon dioxide is also evident, with plants taking up more carbon dioxide during spring and summer than in winter.Source: CAPE GRIM BASELINE AIR POLLUTION STATION, BUREAU OF METEOROLOGY, PAUL FRASER and

PAUL STEELE, CSIRO DIVISION OF ATMOSPHERIC RESEARCH, and WATSON ET AL. 1990

FIGURE 11: THE CARBON CYCLE

Uptake and release byOceans and marine biota

Atmosphere(e.g. CO2)

Sedimentation(e.g. limestone, coal)

Biota

Uptake byvegetation

Respirationand decay

Burning of fossilfuels

Landclearing and

fire

Volcanoes

Soils, peat

N2O

(pa

rts

per

bill

ion)

1980 1985 1990 1995290

310

300

CFC

-11 (

part

s pe

r tr

illi

on)

0

100

200

300

1980 1985 1990 1995

CFC

-12 (

part

s pe

r tr

illi

on)

1980 1985 1990 19950

200

400

600

CFC

-113 (

part

s pe

r tr

illi

on)

1980 1985 1990 19950

30

60

90

CO

2 (

part

s pe

r m

illi

on)

1977 1979 1981 1983 1985 1987 1989 1991 1993330

340

350

360

CH

4 (

part

s pe

r bi

llio

n)

1600

1650

1700

1985 1990 1995

Pre-industrial level

280 ppm

Pre-industrial level

800 ppb

Pre-industrial level

288 ppb

Pre-industrial level

0 ppt

Pre-industrial level

0 ppt

Pre-industriallevel

0 ppt

diurnal cycle evident at the local level, as plants take upcarbon dioxide during the day (when they are photo-synthesising), but release it at night. Hence, in vegetatedareas, there is a marked drop in carbon dioxide levels latein the day.

Other gases, although in much smaller quantities, aremuch more effective at absorbing infrared radiation, andhence trapping heat in the earth’s atmosphere. Over a 100year period, the global warming potential of methane isaround 20 times that of carbon dioxide, nitrous oxide is270 times better, while CFCs are several thousand timesmore efficient than carbon dioxide (Houghton et al. 1990).All of these gases have increased markedly in recent years(Figure 12).Indicator theme: Concentration of gases in the atmosphere that contribute

to an enhanced greenhouse effect (Figure 12).

For simplicity, these are combined when developingscenarios of future climate change, and are often expressedas an equivalent concentration of carbon dioxide.

The level of methane has risen significantly above naturallevels with the increase in intensive agriculture (e.g. entericfermentation in animals). Waste decomposition, especiallylandfill, has also been a major contributor, as have someemissions from the energy sector. Nitrous oxide is also anatural gas that has increased due to some industrialprocesses, to agriculture (especially fertiliser use) and to thetransport industry. The use of CFCs by industry for refriger-ation, aerosol sprays and foams is now largely controlled,but their long life means that they will continue to absorbradiation and contribute to an enhanced greenhouse effectfor centuries to come.

ATMOSPHERE 1.11

TABLE 2: STATE AND TERRITORY EMISSIONS AND SINKS IN CARBON DIOXIDE EQUIVALENTS(1988 AND 1990) FROM THE NATIONAL GREENHOUSE GAS INVENTORY

State/Territory Gross emissions Gross sinks Net emissions Net emissions

in 1990 (kilotonnes) in 1990 (kilotonnes) in 1990 (kilotonnes) in 1988 (kilotonnes)

New South Wales 202 329 27 304 175 025 166 808

Queensland 171 232 15 724 155 508 152 259

Victoria 119 278 13 703 105 575 99 144

Western Australia 60 712 14 396 46 316 39 648

South Australia 38 381 3 766 34 615 33 773

Northern Territory 10 792 436 10 356 10 435

Tasmania 16 739 15 958 781 90

Australian Capital Territory 2 241 384 1 857 1 776

Source: adapted from NATIONAL GREENHOUSE GAS INVENTORY COMMITTEE 1996

TABLE 3: SECTORAL CONTRIBUTIONS TO GROSS GREENHOUSE GAS EMISSIONS FOR 1990FROM THE NATIONAL GREENHOUSE GAS INVENTORY

Sector Gas Emissions Global warming CO2 equivalents Percentage

(kilotonnes) potential (kilotonnes) contribution

All energy CO2 3 791.0 1 3 791.0

CH4 0.95 21 19.95

N2O 0.06 290 17.4

Total 3 828 23

Industrial processes CO2 500.0 1 500.0

CF4 0.06 5 100 306.0

C2F6 0.006 10 000 60.0

Total 866 5

Agriculture CH4 91.38 21 1 918.98

Total 1 919 12

Land use change CO2 9 458.0 1 9 458.0

& forestry CH4 6.4 21 134.4

N2O 0.06 290 17.4

Total 9 610 57

Waste CH4 24.56 21 515.76

Total 516 3

All sectors Total 16 739 100

Source: adapted from NATIONAL GREENHOUSE GAS INVENTORY COMMITTEE 1996

Australia contributes only between 1 and 2% of the grossglobal greenhouse gas emissions (Lehane 1995). However,Australia does have a high per capita emission rate, primar-ily because of the higher proportion of energy-intensiveindustries in Australia. Tasmania’s contribution is shown inTable 2, which is broken down by sector in Table 3.Indicator theme: Tasmania’s contribution to greenhouse gas emissions

(Table 2 and 3)

Understanding the sources of greenhouse gas emissions iscritical to providing a strategy for control that is appropri-ate for the economic and social conditions of an area.Global emission rates may be reasonably well understood,but these vary considerably between regions. Coal burntfor electricity production is a significant source of carbondioxide emissions in Victoria, whereas Tasmania’s relianceon hydro-electric power results in much lower carbon diox-ide emissions from coal burning (Kinrade 1990).

However, concern has being raised that hydroelectric powermay also be a source of greenhouse gases. As a lake growsafter dam construction, the vegetation and soil is coveredby the water and starts to decompose, releasing carbon intothe atmosphere (primarily as carbon dioxide andmethane). Observations on hydro-electric lakes inTasmania suggest that after an initial rapid decay of somevegetation in a newly flooded lake, decay rates decrease toa level similar to, or less than, the rate of photosynthetic-fixing of carbon taking place in the lake, resulting in a slowbuild-up of organic matter on the lake floor. Research onCanadian and Swedish lakes suggests that the emissionrates of carbon are low (Chamberland et al. 1996,

Svensson & Ericson 1993), and for the power generated,significantly ‘cleaner’ than other power generation meth-ods. Chamberland et al. (1996) indicate that powerstations fueled by gas, oil and coal have respectively 18, 29and 34 times the carbon dioxide equivalent emissions thanhydro-powered stations for the same amount of power gen-erated.

As part of its international obligations, including theFramework Convention on Climate Change signed at theUnited Nations Conference on the Environment andDevelopment in Rio de Janeiro in 1992, Australia mustreport on its emissions of greenhouse gases (see Table 2and 3). It has become clear that the accuracy of estimatesof emissions from different sectors across Australia is veryvariable (e.g. the importance of above and below groundbiomass as storages of carbon, and the release of carbondue to land clearance). Research is continuing to improvethe accuracy of the estimates.

Ozone Ozone is a naturally occurring gas whose existence in thestratosphere is vital to life on earth. The ozone layer acts asa shield, absorbing around 90% of harmful ultraviolet(UV) radiation from the sun. UV radiation is the cause ofsunburn and can lead to skin disorders, including skincancer. It also causes problems with other sensitive tissues,such as those of the eye, where it can cause cataracts andtumours. UV radiation also damages the immune system,and can cause genetic mutations and a loss of productivity

ATMOSPHERE 1.12

FIGURE 13: FORMATION AND DESTRUCTION OF OZONE IN THE STRATOSPHERE

Source: adapted from CROWDER 1995

Reactive nitrogen (N), hydrogen (H) and bromine (Br) can all act

in the same manner as chlorine (Cl)

Free chlorine atom

breaks apart

ozone

molecule

UV radiation of around 290 nm causes ozone

to split into molecular and atomic oxygen

Reactive atomic oxygen combines with an

oxygen molecule to form ozone

UV radiation breaks

off a chlorine atom

from a CFC-11

molecule

Chlorine now free

to continue the

cycle

This combines with free oxygen to form

oxygen molecules

UV radiation of around 240 nm splits

molecular oxygen into atomic oxygen

Natural formation and destruction Chemical induced destruction

in plants. Ironically, while ozone is essential in the upperatmosphere, it is a toxic pollutant in the lower atmosphere,causing serious irritation to the nose and throat.

The ozone layer is concentrated in the stratospherebetween 15 and 30 km above the earth. Despite the size ofthis layer, ozone is still scarce amongst the other gases.Here, ozone is naturally and continuously being formedand destroyed by a simple chemical reaction. When UVradiation of wavelengths 180–242 nanometres (nm) isabsorbed by molecular oxygen (O2), it breaks apart intotwo atoms of oxygen (O). Each of these then reacts withother oxygen molecules to form ozone (O3). When theozone absorbs UV radiation of longer wavelengths—up to320 nm—the ozone breaks down again into itsconstituents (O2 and O) (Figure 13). This absorption ofUV radiation is the main reason for the sharp temperaturerise in the stratosphere.

Increases in certain chemicals can shift the balance ofozone production and destruction. In this century, therehas been a significant rise in the concentration of gases thatcause the destruction of ozone. The amount of ozone inthe stratosphere is being reduced and more UV radiation isreaching the earth’s surface.Indicator theme: Global and Tasmanian emission rates of ozone-depleting

substances.

The most significant of the ozone-depleting chemicals arethe chlorofluorocarbon (CFC) and halon groups, andnitrous oxide. CFCs and the related hydrochlorofluorocar-bons (HCFCs) have been used in many applications sincetheir invention in the late 1920s. They make excellentcoolants for refrigeration and air-conditioning, and their

ability to trap heat makes them ideal for foam insulation.Hence they were in widespread use before it was realisedthat, although they are stable compounds in the loweratmosphere, they would break apart in the stratospherewhen subjected to high levels of radiation. Furthermore, asthese types of chemicals also tend to have long lives, theyremain in the stratosphere, destroying ozone for manyyears (Table 4).

The worst affected areas are over the polar regions. Due tothe unique atmospheric conditions in winter, ice particlesin the atmosphere transform chlorine and bromine com-pounds into particularly destructive agents, which reducethe ozone concentration dramatically when the sun returnsin the spring. The ‘hole’ in the ozone layer is replaced dur-ing summer with ozone from lower latitudes (i.e. fromtemperate and tropical regions).

ATMOSPHERE 1.13

MAP 6: ANTARCTIC OZONE HOLE

These figures show the dramatic development of the ozone ‘hole’ over Antarctica during Spring since 1979.Source: PAUL LEHMANN, BUREAU OF METEOROLOGY

TABLE 4: ATMOSPHERIC LIFESPAN OFSOME OZONE-DEPLETING GASES

Gas Formula Average lifetime

in atmosphere (yrs)

CFC11 CFCl3 65

CFC12 CF2Cl2 130

CFC113 C2F3Cl3 90

Halon1301 CF3Br 110

nitrous oxide N2O 150

methane CH4 10

Source: WATSON ET AL. 1990

1994

1979 1987

1983 1991

400 300 200 100Dobson ozoneunits

While aspects of the process are natural, the extent towhich the ozone hole has developed over Antarctica inrecent years has been extreme. Increased depletion, cou-pled with less ozone from lower latitudes replacing thehole (due to general ozone loss around the globe) hasmeant that the hole has been particularly severe in recentyears (Map 6).

Indicator theme: Trends in upper atmosphere ozone concentration

While ozone is being replenished over Antarctica, ozone-deficient air gets caught up in atmospheric air flows that

transport the ‘hole’ to lower latitudes. Tasmania’s geo-graphical position means that ozone-depleted air can passover the State in spring and early summer. The effects onthe health of Tasmanians can be severe, for in these condi-tions the level of skin-damaging UV radiation increasesdramatically (Case Study 2).

On realising the damage being done to the ozone layer,many countries, including the United States of America,banned the sale of aerosol spray cans containing CFCs in1979. CFC production was abruptly reduced.

ATMOSPHERE 1.14

CASE STUDY 2: OZONE AND UV-BRADIATION IN HOBART

PRESSUREUltraviolet (UV) radiation is a

part of the radiation spectrum

that reaches the earth from the sun

(Figure 2). Most is absorbed by the

atmosphere, especially the ozone

layer, but a significant amount reaches

the earth’s surface. Particular wavelengths, especially

those around 285 nanometres (nm), can be harmful to

plants and animals. They are termed ‘erythemal UV-B

radiation’. The effects range from sunburn and skin

cancer in animals to mutations in plants, and can be

lethal in high doses. The effects are much less

significant with longer wavelengths in the UV-A region.

STATEErythemal UV-B radiation follows the normal pattern for

all solar radiation. It is dependent on the elevation of the

sun above the horizon and the day of the year. It reaches

a maximum at noon and goes to zero between sunset

and sunrise. However, cloud cover can reduce the UV-B

received at the earth’s surface, as can a heavily pollut-

ed atmosphere. In addition, unlike other parts of the

solar spectrum, erythemal UV-B radiation is absorbed by

stratospheric ozone. A drop in the ozone concentration

will increase the UV-B erythemal irradiance at the

earth’s surface, with consequences to plant and animal

life on the planet (Tevini 1994).

RESPONSETo increase understanding of the effect of ozone loss

and cloud cover on UV-B radiation, a detailed monitoring

program was started in October 1994 at the Depart-

ment of Geography and Environmental Studies at the

Hobart campus of the University of Tasmania. The UV-B

measuring instrument uses a filter/detector system that

mimics closely the sensitivity of the human skin to ultra-

violet radiation, with a maximum sensitivity at 297 nm,

in the erythemal UV-B region. It decreases to a value

close to zero at 350 nm and beyond, in the UV-A region.

Figure 14 shows daily erythemal UV-B radiation recorded

at the University. The difference between the two data

sets represents the extra depletion by clouds. Heavily

overcast days may deplete more than 90% of the

incoming erythemal UV-B radiation. On the other hand,

some partly cloudy days may reflect UV radiation from

the sides of the clouds down to the surface, increasing

the daily load to values higher than the clear sky.

By selecting cloudless days, the effect of ozone may be

examined without the masking effect of cloud cover. The

4% drop in ozone observed for the southern hemisphere

latitude of Hobart between 1979 and 1989 has caused

an increase of just over 5% in UV erythemal irradiance at

the earth’s surface (Madronich 1992).

Levels of daily erythemal UV-B irradiance are a complex

function of day of the year, cloud cover and total ozone

levels. Detecting a long-term trend in UV-B irradiance as

a result of ozone depletion is difficult because of the

variability of cloud cover. Of equal importance to cloud

effects is the time of the year when the ozone depletion

occurs. Small ozone losses in winter would not have the

same effect as in summer. Ozone-depleted air has been

recorded moving from Antarctica over southern Australia

during spring and early summer (Atkinson et al. 1989)

with significant increases in the erythemal UV-B irradi-

ance at Hobart (Nunez et al. 1994). If this continues,

increased UV-B irradiance will appear between October

and January, with resulting effects on the health of

humans and other animals, and plant productivity.

Clearly, there is a need for global change studies to

monitor surface UV irradiance as well as ozone.

Fortunately the quality and reliability of instruments that

monitor UV-B radiation have improved dramatically, so

trends may be observed with some confidence. The full

impact of ozone depletion will be known only when UV-B

irradiance data sets extend over many years.Indicator theme: Trends in surface UV-B levels for Tasmania

FIGURE 14: ERYTHEMAL UV-BRADIATION IN HOBART

Vertical bars represent daily measurements at

the University of Tasmania; the thin line

represents clear-sky values calculated from a

mathematical model. The model takes the ozone

level, solar elevation and day of the year into

account, but ignores cloud effects. Missing

values represent days in which ozone data were

not available. Source: MANUEL NUNEZTime

Irra

dian

ce (

KJ/

m2/

day)

19 Oct 18 Nov 18 Dec 17 Jan 16 Feb 18 Mar 17 Apr 17 May 16 Jun0

1

2

3

4

5

6

7

The Vienna Convention for the Protection of the Ozone Layerwas signed in 1985, and the Montreal Protocol on Substancesthat Deplete the Ozone Layer in 1987. The Protocol wasamended in 1990 and 1992 to make the controls on ozone-depleting substances more stringent and expand the list ofchemicals that can cause a depletion of the ozone layer.

Australia adopted a Strategy for Ozone Protection in 1989,with a revision in 1994, under the requirements of theMontreal Protocol. This will see the phasing-out or controlof specified chemicals by, or before, the target dates of theProtocol.

Tasmania’s Environmental Management and Pollution ControlAct 1994 incorporates ozone-protection legislation whichcommenced on 1 July 1995, superseding the Chlorofluoro-carbons and other Ozone Depleting Substances Control Act1988. It complements the Federal Ozone Protection Act 1989and is intended to reflect national obligations under theMontreal Protocol. This strategy calls for a phase-out ofozone-depleting chemicals such as chlorofluorocarbons(CFCs) and halons, and thus supports the development ofozone-friendly technology in applications such as refrigera-tion, air-conditioning, and fire-control.

The sale or use of any of the substances listed in the legisla-tion is now restricted to those who are authorised by theDirector of Environmental Management, such as firms andaccredited individuals operating in the refrigeration andair-conditioning industry. They must also adhere to rele-vant Australian and New Zealand Environment andConservation Council (ANZECC) endorsed industry codesof practice designed to limit emissions of ozone-depletingsubstances. Those buying and selling controlled substancesare also required to record and report quantities bought,sold and held in stock, which should assist in monitoringthe run down in usage of ozone-depleting substances inthe State.

The Environmental Management and Pollution Control Act1994 also requires an authorisation to be held in order topossess a portable halon fire-extinguisher after 31December 1995. Such authorisations have been issuedonly where the extinguisher is considered to have essential-use status. So far this has been confined to cases where theyare carried in aircraft to meet safety requirements, pendingthe approval of an alternative extinguishing agent by theCivil Aviation Safety Authority.

To control the supply, collection and eventual destructionof halons, the Federal Government started the Halon Bank,operated by the Department of Administrative Services’Centre for Environmental Management. During the closingweeks of 1995, the Halon Bank, in conjunction with theTasmania Fire Service, mounted a recall campaign forportable halon fire-extinguishers in the State.

Contrary to the ANZECC ozone-protection strategy, and incontrast to the situation with portable halon fire-extinguishers, the Environmental Management and PollutionControl Act 1994 does not create a requirement for non-essential ‘fixed’ halon fire-control systems to bedecommissioned. Amendment of the Act to overcome thisshortcoming is under consideration. However, decommis-sioning of fixed halon fire-control systems in Tasmanianpremises has been proceeding on a voluntary basis.

Halon Bank statistics indicate that by the end of April1996, 27.9 tonnes of halon 1211 (the type used in portableextinguishers) and 12.8 tonnes of halon 1301 (the typeused in fixed systems) had been recovered in Tasmania.Over 60% of the halon 1211 came from private individuals

and small business, a substantially higher proportion thanfor any other Australian state or territory.

While the problem of ozone depletion is global,individuals can help reverse the depletion trend. Car air-conditioning systems still use ozone-depleting substances,and need regular use to ensure seals are kept lubricated tostop them cracking and leaking. The systems also needregular servicing.

Preventing leakage from refrigerators is also crucial toreducing ozone depletion. Damage, such as that causedwhen scraping freezers with a knife, can allow ozone-depleting substances to escape. Disposing of old freezersand refrigerators should be done through an authorisedagent or wholesaler to ensure that the ozone-depleting sub-stances are properly removed.

Together, all these actions are helping to reduce theamount of ozone-depleting substances being released intothe atmosphere. However, their long life span means thatthey will continue to cause a decline in the ozone layer formany years to come.

Future climate changesSuch changes in the atmosphere as an enhancement of thegreenhouse effect and ozone depletion will have wide-spread ramifications for climate change. However,predicting just how and in what size, shape or form thesechanges are likely to develop is complicated by manyuncertainties. In particular, timing, magnitude and regionaldifferences are very difficult to quantify. It is unlikely thatclear indications of climate changes will be seen foranother decade or more.

Nevertheless, natural variability alone cannot account forthe recent changes in climate that have been observed.The Intergovernmental Panel on Climate Change has in thepast stopped short of saying that humans are causingchanges to the climate. However, draft versions of its 1996report now positively state that humans are the cause ofsome aspects of the changes.

The latest Intergovernmental Panel on Climate Changefindings (Lehane 1995) suggest that a doubling of presentCO2 levels will cause a 2.5°C (range 1.5–4.5°C) rise inaverage global temperature. This translates to averageglobal sea levels being about 20 cm higher by 2030 (only34 years away) and around 65 cm higher by 2100 if thecurrent rate of emissions continues. The rise would occurprimarily because water expands as it heats up (thermalexpansion). Some land ice and snow would melt, adding asmall component to sea level rise, but this would be partlyoffset by higher precipitation (e.g. snow falls in high-altitude and polar regions) because of the increasedevaporation caused by the warmer conditions.

The ramifications of such climatic changes are widespread.Agriculture is particularly susceptible to climatic variation(see ‘Agriculture’ chapter). For example, changes in rainfallmay assist some areas, but cause crop failure, land degrada-tion and erosion in others. Change in temperature mayexpand the range of some pests and diseases, and somecrops that require winter chill to set fruit may becomeunviable in some areas. An increasing number of hot dayscould lower the quality of crops such as wheat.

Some Tasmanian species may become extinct with climatechange (see also p. 4.26). The alpine zone in particularcould be ‘pushed off the tops’ of mountains if temperaturesrise too much.

ATMOSPHERE 1.15

Many population centres in Tasmania have low-lyingcoastal areas. Rises in sea level are unlikely to make any ofthese centres uninhabitable, but the higher tides, stormsurges and the raising of groundwater levels may makethem unviable (see also ‘The Effects of Climate Change’,p. 7.64).

Australian scientists are involved in many studies to quan-tify climate and sea level change, and the impacts futurechanges would have. The studies range from measuring soilmoisture and run-off in catchments around the country, tomonitoring changes in the upwelling of cold, nutrient-richwaters around the coast. Two of the programs in whichTasmania has a role are the Australian Baseline Sea Level

Monitoring Project and the atmosphere monitoring stationat Cape Grim.

To collect accurate information on sea-level change, severalSEAFRAME (Sea Level Fine Resolution Acoustic MeasuringEquipment) sites have been set up around the coast ofAustralia. One site at Spring Bay, on Tasmania’s east coast,is providing precision measurements of sea level for base-line data. It measures the sea level to an accuracy of amillimetre every second, which is then averaged over threeminute periods. The site is also used by the National OceanService of the US National Oceanographic andAtmospheric Administration as part of their global oceannetwork. The project has found significant local and

ATMOSPHERE 1.16

TABLE 5: TASMANIAN CLIMATE-CHANGE SCENARIOS

Climatic Condition Scenario Source

Temperature Based on scenario for south coast of Australia. Whetton et al. (in press)

• Increases in the range of 0.5 to 2.0°C by the year 2030,

and 1 to 5°C by 2070.

Rainfall Uncertain future conditions.

• CSIRO models indicate that rainfall would increase over Whetton et al. (in press)

Tasmania and become more intense. Summer rain may

increase up to 20% across Australia by 2030, and up to

40% by 2070. Winter rain may increase up to 10% in south

and eastern Australia by 2030, and up to 20% by 2070.

• Regional models suggest a decrease in precipitation and McGregor & Walsh (1994)

fewer storms in January; and an increase in precipitation

and more storms in July.

• Other studies may suggest a decrease in annual rainfall Nunez (unpublished data)

in Tasmania.

Pressure systems Based on scenario for south coast of Australia.

• Deeper low pressure systems in the Tasman Sea McInnes et al. (1992)

(associated with rises in sea temperature).

• High pressure systems move further south in the Nunez (pers comm)

summer months.

Wind Based on scenario for south coast of Australia.

• Stronger westerly winds (associated with low-pressure McInnes et al. (1992)

systems)

• General strengthing of low-level winds during July (winter) McGregor & Walsh (1994)

Mean sea level Based on global ‘business-as-usual’ scenario. IPCC in Lehane (1995)

• Rise of 6 cm on average (3 to 10 cm) per decade.

• Expected rises (cm)

Year 2030 2070

Low 10 30

Probable 20 65

High 30 110

Storm surge Based on scenario for south coast of Australia.

Storm surges increase in frequency and intensity due to: Ingle Smith (1990) and

• Deeper low-pressure systems in the Tasman Sea McInnes & Hubbert (1994)

(associated with east coast lows)

• Stronger westerly winds.

Associated phenomena: McInnes et al. (1992) and

• Higher wind waves (associated with stronger winds) Short (1988)

• Higher tides (associated with deeper lows and stronger

onshore winds)

• Increase in precipitation (associated with low-pressure

systems)

• Potential for increased coastal and estuarine flooding.

Source: adapted from DEPARTMENT OF ENVIRONMENT AND LAND MANAGEMENT 1996

regional variations in Australia. The 38 stations in Australiathat provide a continuous record of longer than 11 yearsshow annual rates of sea-level change from a fall of 2.3 mmper year to a rise of 6.2 mm a year. However, three stationsprovide a much longer record, indicating that the averagesea-level rise around Australia has been 2.2 mm per year(Lehane 1995).Indicator theme: Trends in sea level on regional and global scales

Cape Grim, at the north-west tip of mainland Tasmania, isproviding crucial baseline information on the compositionof the atmosphere. It is part of a global network of stationsmeasuring a wide range of gases and aerosols. The databeing collected are helping scientists understand thechanges that are occurring in atmospheric compositionand climatic conditions (see Case Study 1).

The CSIRO Division of Atmospheric Research estimatesthat, assuming the continuation of present conditions,temperatures will rise 0.5–2.0°C across Tasmania andsouth-eastern Australia by the year 2030 (Lehane 1995).Summer rains would generally rise across the country byup to 20%, while winter rain would also increase in south-ern and eastern Australia. The intensity of rainfall is likelyto increase and the period between falls to decrease. Run-off and soil-moisture studies suggest that the change inrun-off will be greater than the change in rainfall. Together,these would cause much more frequent flooding. Despitethis, studies have suggested that the danger of fire wouldalso increase across Australia.Indicator theme: Trends in annual and seasonal temperatures and

precipitation ratesIndicator theme: Frequency and severity of extreme climatic events (high

temperatures, heavy rains, storms)

Sea level rises coupled with stronger storms will increaseerosion of ocean and estuarine shorelines, and inundatemore low-lying areas. Changes in salt levels in estuariesand coastal lakes will affect fisheries and disturb theecology of coastal wetlands.

But the scenarios for what will happen in the future areoften not consistent. Table 5 shows some of the scenariosthat have been suggested.

The reason for such diversity in the scenarios is that there isan incomplete understanding of the linkages in the wholeclimate system. For example, changes in the temperaturecause changes to the amount of evaporation. Watermolecules are one of the most effective greenhouse gases,trapping even more heat in the lower atmosphere.However, with more water in the atmosphere, more cloudsalso form. Clouds reflect some solar radiation away fromthe earth, slowing down the warming process.

Particulates and sulfate aerosols also act as inhibitors toglobal warming. Released by volcanoes and the burning ofvegetation and fossil fuels, their increasing abundance inthe atmosphere will slow down the rates of global warm-ing. Early models of climate change did not take intoaccount the effect of such substances, so tended to over-estimate the effects of climate change. Newer models areincorporating their effect and, as a result, are more effective

at modelling the climate system, particularly the observedrise of 0.5°C in the average global temperature this century(Pittock 1995).

More frequent storms bringing more rain may be beneficialto some areas of the State, particularly the agricultural areasof the midlands and the east, but many areas would not beable to cope with such heavy rains. Extensive flooding insouth-eastern Tasmania in February and April 1996 high-lighted the inability of some stormwater and sewagenetworks to cope with heavy rains. Serious erosion was alsorecorded, severely affecting the quality of estuarine andcoastal waters in the south and east of the State.

Increased carbon dioxide levels can, if nutrients are avail-able, enhance the growth of some plants. However,agricultural yield may not always increase; it can reach apeak, after which further increases in carbon dioxide causea decline in productivity. One study suggests thatAustralian wheat productivity would increase until the2030s, followed by a decline after 2050 (Rosenzweig &Hillel 1995).

Globally, it is the developing countries that would havetheir ‘all food yield’ affected most by climate change. Bythe middle of next century, developing countries may havea decrease in all food yield, and with increasing worldmarket prices, there would be a significant increase in thenumber of people at risk from starvation (Pittock 1995).

Future emissions will largely determine the degree ofclimate change experienced. Scenarios are usually based onan equivalent of the doubling of the level of carbondioxide. A key aim of the Intergovernmental Panel onClimate Change is to bring carbon dioxide equivalent con-centrations below the level that would threaten foodproduction and prevent sustainable economic develop-ment. However, the time lag in the system means that evenif all anthropogenic emissions were to be suddenly stopped,changes would still be occurring for decades to come. It istherefore imperative to act quickly.

Australia, through the National Greenhouse ResponseStrategy (which has been endorsed by Federal, State andlocal governments), is aiming to reduce greenhouse gasemissions to 1988 levels by the year 2000, with a further20% reduction by 2005 (Lehane 1995). However, this goalis qualified by the proviso that the reduction does not haveany net adverse effects on Australia or its trade competitive-ness, without similar action by other countries. In 1994, itappeared that Australia would be producing 7% above the1990 level (an equivalent of 610 million tonnes of carbondioxide) by the year 2000. Additional measures wereannounced in March 1995 aimed at reducing this to 3%above the 1990 level. Intergovernmental and advisory pan-els representing scientific, technical, industrial,administrative and conservation interests have been set upto further develop the strategy and ensure its implementa-tion.Indicator theme: Number of targets achieved under the National

Greenhouse Response Strategy

ATMOSPHERE 1.17

Air QualityThe air sweeping in from the west and south of Tasmaniahas travelled over thousands of kilometres of ocean, whichprovides time for many pollutants to be removed from thisair through natural processes (mainly through cloud for-mation and rainfall into the sea). This exceptionally cleanair is then modified by natural and human activities withinthe State. For example, the air blowing into Tasmania fromthe south-west, as measured at Cape Grim, contains only0.04 parts per million of carbon monoxide—roughly 100times less than that measured in central Hobart.

In a few areas, air quality has deteriorated substantially.The small population and small number of large industriesmeans that large-scale air pollution is unlikely. It is only inurban areas and near some large industrial sites that airpollution is regularly a problem. By international compar-isons the existing air quality is good, but Tasmania pridesitself on its ‘pristine’ environment, and markets its produceand sells itself as a tourist destination with this ‘clean,green’ image. For these reasons, the State must maintainvery high standards of air quality, not merely those thatwould be considered acceptable elsewhere.

Detailed monitoring of air quality is an expensive andlabour-intensive task. Consequently, only specific problemareas have been monitored regularly, so it is difficult toprovide much quantitative information on air quality inthe State. Further systematic monitoring of air quality isrequired.

Condition of the atmosphereThe effect of pollutants in the atmosphere on humanhealth, property and amenity depends on the type ofpollutant, its concentration in the air, and the length oftime people or property are exposed to it. Exposure to highconcentrations for a short period may cause adverse effects,as might exposure to much lower concentrations over longperiods. For this reason, air quality is usually judged from acombination of maximum ‘acceptable’ or ‘desirable’ con-centrations of selected pollutants over short periods, sayone hour, and also longer periods such as annual averages.Measured long-term concentrations are useful for establish-ing trends in air quality, while short-term measurementswill identify specific pollution sources.

For some substances, the maximum allowable concentra-tions are specified in regulations. If they exceed regulatedlimits, the law requires that action must be taken to reducethem. For other substances, no limits are specified inTasmanian regulations, but there are guidelines, usuallybased on regulations adopted in other countries, that sug-gest a safe limit for the concentration of the substance.They do not, however, impose a legal requirement to limitthe concentration of the pollutant.

For a third group of substances, there are no regulatedlimits or guidelines available. However, if there is localevidence that people’s health or the environment is beingharmed, the general provisions of the EnvironmentalManagement and Pollution Control Act 1994 require actionto reduce the pollution. Sometimes pollution levels areconsidered unacceptable to the community, even thoughno specific regulations have been breached. For peoplewho are inconvenienced, or consider that a nuisanceexists, the pollution problem is sometimes easily fixed,but there may be protracted debate about whetheranything should be done to reduce the problem.

In all these cases, pollution levels can be considered’unacceptable’—which not only covers a demonstratedrisk to health, property or the environment, but alsoincludes contaminants in the air which the communitydecides are more than it should be expected to tolerate.

Air quality may reach particularly poor levels if the topog-raphy and weather conditions allow a gradual build-up ofpollutants. In Tasmania, pollutants disperse most readilyin towns built on the coast, which tend to have morewind. But even on the coast, pollution can reach unaccept-

ATMOSPHERE 1.18

TABLE 6: KEY AMBIENT AIR-QUALITY GUIDELINES

Pollutant Limit Measurement period

Fine particles 120 µg/m3 24 h average

(i.e. <10 µm diameter) 40 µg/m3 annual average

Total Suspended Particulates 90 µg/m3 annual average

Lead 1.5 µg/m3 3 month average

Carbon monoxide 34.4 mg/m3 (30 parts per million) 1 h average

11.5 mg/m3 (10 parts per million) 8 h average

Nitrogen dioxide 280 µg/m3 (0.15 parts per million) 1 h average

110 µg/m3 (0.06 parts per million) 24 h average

Sulfur dioxide 450 µg/m3 (0.17 parts per million) 1 h average

150 µg/m3 (0.06 parts per million) 24 h average

Source: NATIONAL HEALTH AND MEDICAL RESEARCH COUNCIL

FIGURE 15: DUST FALLOUT NEAR PORT LATTA,RAILTON AND ELECTRONA

Pollution levels can be high around large industrial sitesSource: ENVIRONMENT TASMANIA

1975

Du

st (

mg/

m2/

day)

300

250

200

150

100

50

01980 1985 1990

Port Latta

RailtonElectrona

able levels if there is a large source of pollution, as at PortLatta (Figure 15), where an ore-pelletising plant operates.Inland towns are often established in sheltered areas invalleys, which have poor dispersion in winter monthswhen low-altitude temperature inversions (see p. 1.6) andlow wind speeds are more common. These conditions cantrap pollutants, allowing them to build up to unacceptablelevels.

Some pollutants will be more significant than others fordifferent regions, depending on the sources and the cli-mate. Tasmania, for example, will be less concerned aboutphotochemical smog because it has comparatively fewmotor vehicles (one of the main sources of pollutants lead-ing to photochemical smog) but more concerned aboutsmoke from domestic wood fires because of the cooler cli-mate and popularity of wood heaters in homes.

The air pollutants of most relevance to Tasmania can begrouped into two broad classes: particulates and gases.

Particulates can be further divided into larger particles withdiameters greater than 50 µm (0.050 mm), which tend tosettle out of the air quite quickly, and smaller particles,which may stay suspended in the air for long periods.Of the smaller particles, those with diameters less thanabout 2 µm (0.002 mm) are of particular concern becausethey travel deep into the lungs if inhaled.

The larger particles include dust blown off roads or stock-piles of ore at processing plants. They may also come frompoor combustion of solid fuels (e.g. coal) or waste (e.g.sawdust). Some of these larger particles are classified as‘nuisance dusts’; they do not directly affect healthadversely, but they can damage property and can certainlybe a nuisance. But some of the dust may contain heavymetals that can contaminate soil and water. The miningand metal processing industries in Tasmania are potentialsources of such dusts (Case Study 3).

Fine and ultra-fine particles arise from combustion pro-

ATMOSPHERE 1.19

CASE STUDY 3: LUTANA HEAVY METALSCONTAMINATION

PRESSUREOver the last 70 years, the

operations of the Pasminco

Metals–EZ zinc refinery have

deposited lead and cadmium dust,

most notably in the Hobart suburb of

Lutana. Heavy metal contamination can

lead to health problems. The main source of the

contamination has been attributed to the stockpiles of

ore, product, and by-products at Pasminco Metals–EZ.

Environment Tasmania is studying the effect of this dust

deposition on levels of lead and cadmium in the soil,

vegetables and household dust in

the Lutana area.

STATEStudies of the environmental

effects of heavy metal

contamination are continuing.

Further assessments will be

made of lead and cadmium

concentrations in the outdoor soil

and in household dust and their

uptake by vegetables.

Initial studies into soil

concentrations showed that the

distribution of contamination is

consistent with wind patterns

and dust dispersion estimates

throughout the Lutana area

(Map 7).

The levels of cadmium being

taken up by home-grown

vegetables in many cases

exceeded the National Food

Authority’s maximum permitted

concentration in vegetables to be

sold. The results confirmed previous work from other

areas that found carrots and silverbeet are particularly

high cadmium accumulators.

A urinary cadmium study of Lutana residents found no

significant difference between their mean urinary

cadmium concentration and that of residents in the St

Leonards control area. A study of the level of lead in the

blood found that no individual studied exceeded the

National Health and Medical Research Council’s ‘level of

concern’ at that time.

RESPONSEFollowing the discovery of contamination, a stockpile

management plan was undertaken to prevent further

contamination. Apart from the wharf facility, this

program is now substantially complete.

LUTANA

PRINCE OFWALES

BAY

Reservoir

NEW TOWNBAY

ROAD

RIS

DO

N

ASH

BO

LTLEN

NO

XAV

ENUE

BO

WEN

R

OA

D

CR

ESC

ENT

CEN

TRA

L AVEN

UE

FLETCH

ER AV

ENU

E

BROOKER

AVENUE

ROAD

PAR

K

DER

WEN

T

PASMINCO METALS EZ

HEC

Quarry

Quarry

EZ RISDONGOLF COURSE

TENNISCOURTS

NEW HOUSING

LADY ASHBOLTKINDERGARTEN

TOTAL CADMIUM IN

SURFACE SOIL (mg/kg)

>50

20 – <50

5 – <20

<5

0 100 200 300

lower impact

background

higher impact

metres

MAP 7: CADMIUMCONCENTRATION INSURFACE SOIL, LUTANA

Source: ENVIRONMENT TASMANIA

cesses, notably wood heaters, diesel engines and smeltingof metals. Incineration and open burning can also besources of fine particles. These smaller particles are cur-rently the focus of international attention by health andpollution control authorities, who are moving towardsstricter controls over sources. There is an urgent need formore routine monitoring of these fine particles in urbanareas and some of the smaller towns across the Statebecause of the health risks associated with this type of pol-lutant.Indicator theme: Trends in concentration of particulates at several

monitoring sites relative to clean-air measurements fromCape Grim

Of the gaseous pollutants in Tasmania, carbon monoxidecomes from the greatest variety of sources. It results fromincomplete combustion of fuel in internal combustionengines, from domestic heaters (chiefly wood heaters),industrial boilers and furnaces, and as a by-product ofsome industrial processes. The other relevant gaseous pol-lutants include acid gases (oxides of sulfur and nitrogen),hydrocarbons, fluorine compounds (which may also be inparticulate form), and odours.

Tasmania does not have legislation that specifies accept-able ambient levels of air pollutants, but has adoptedguidelines based on National Health and MedicalResearch Council recommended limits and limits fromother states. Table 6 summarises the key ambient air-quality guidelines used in the State. These are notenforceable limits, but are a useful guide for rankingefforts to control pollution.

As mentioned, there has been no systematic measurementof air quality in Tasmania, nor any detailed inventory ofemissions. For this reason, discussion of the condition ofthe atmosphere in Tasmania must be largely subjective.Apart from the localised air-pollution problems discussedbelow, Tasmania appears to have excellent air quality.Visitors to the State from more populated areas often com-ment on the blueness of the sky and the freshness of theair. The blue sky is an indication of low levels of dust andother pollutants in the air, which tend to scatter out theblue wavelengths in the sunlight, leaving the sky lookinggreyer or even pink.

One of the few recorded indicators of air quality for whichlong-term data are available is visibility. This has beenrecorded by the Bureau of Meteorology at many sitesaround the State. Since 1950, none of the four major sitesconsidered showed any indication of deterioration, whichconfirms the assumption that there is no broad-scale pollu-tion across the State. Measurements for Hobart, forexample, show an improvement in visibility as indicated bythe frequency of days with visibility less than 11 or 5 km(Figure 16).

However, these broad-scale indicators of air quality such asvisibility or blueness of the sky do not identify localised airquality problems such as pollution in inner city streets(where exhaust fumes from motor vehicles may accumu-late), low-lying suburbs (where smoke from wood heatersmay be a problem), or close to large industries (wherepoint-source emissions can have a significant effect).

Pollution sourcesCombustion processes of all sorts are a major source of airpollutants. The State currently uses about 450 000 tonnesof coal, 890 million litres of petroleum products and730 000 tonnes of firewood and wood waste per year. Inaddition to the 4.8 million tonnes of carbon dioxide thatthis fuel consumption releases (about 10 tonnes per personper year), there are many other gases and particulates in theemissions that can reduce air quality.

ATMOSPHERE 1.20

FIGURE 18: CARBON MONOXIDE CONCENTRATIONSMEASURED IN CENTRAL HOBART

a. Mean monthly levels based on 24 hour monitoring periods.

b. Percentage of monitored days exceeding the World Health

Organisation’s recommended 8 hour levels (9 ppm).Source: ENVIRONMENT TASMANIA

FIGURE 17: LEADED AND UNLEADED PETROL USEIN TASMANIA

Million litres per year.Source: AUSTRALIAN INSTITUTE OF PETROLEUM

FIGURE 16: VISIBILITY IN HOBART

The frequency for which visibility is less than 11 km and 5 km at

9.00 a.m.Source: BUREAU OF METEOROLOGY

<5 km visibility

<11 km visibility

Fre

que

ncy

(day

s/ye

ar)

1970 1980 19900

10

15

20

25

30

35

40

45

1950 1960

5

19851981

Mega

litr

es

(ML)

1989 19930

100

200

300

400

500

Leaded

Unleaded

Total Petrol 1978

1

1980 1982 1984 1986

3

5

7

part

s pe

r m

illi

on

(by

volu

me

)

1979 1980 1981 1982 1983 1984 19850

20

40

60

80

100

1986

Perc

ent

age o

f da

ys

a

b

The transport sector, for example, releases carbon monox-ide, hydrocarbons (unburnt fuel), lead (from leadedpetrol), and organic particulates (from diesel engines) (see‘Environment’, p. 14.5). All these pollutants are cause forconcern, particularly in inner city areas where poor trafficflow and streets bounded by tall buildings may accentuatethe problem. Petrol engines emit more pollutants whenthey are idling, so increased traffic congestion meanshigher pollution because of more cars and less efficientengine operation. Tasmania also has a relatively old stockof vehicles. The newer-model cars fitted with catalytic con-verters produce less pollution, and computer-controlledtraffic lights can improve traffic flow. The move fromleaded to unleaded petrol (Figure 17) will help reduce leadlevels near suburban roads and highways. Together thesecan reduce pollution levels, as demonstrated by carbonmonoxide measurements in Hobart between 1978 and1986 (Figure 18). However, a two-month study in 1991suggested that the levels might have increased again (Power1991) indicating that monitoring needs to be resumed.

To ensure that pollution levels are not creeping up in thelarger urban areas in particular, routine testing is required.This will identify problems before they become a serioushealth threat.Indicator theme: Concentration in urban areas of pollutants (e.g. carbon

monoxide, lead, particulates, hydrocarbons)

Emissions from the industrial sector are very site-specific.For example, Comalco Aluminium (Bell Bay) Ltd in theTamar Valley emits fluorine that concerns farmers in theregion. But the environmental effects of the industrialemissions are complicated by the fact that some fertilisersalso contain fluorine. An Environmental ImprovementProgram, prepared by the company in 1994, indicated thatemissions would be reduced from 6.4 kg of fluorine pertonne of aluminium produced to 3.75 kg/t by the middleof 1996. Tasmanian Electro-Metallurgical Co Pty Ltd, alsoin the Tamar Valley, emits silica fumes and dust. PasmincoMetals–EZ, in Hobart, emits dust that contains heavymetals (Figure 19 and Case Study 3), and the associatedsulfuric acid plant may be a source of acid gases. GoliathPortland Cement Co Ltd, in Railton, is a source of dust

particles (Figure 15). Smaller industries scattered aroundthe State, such as sawmills and foundries, can be a sourceof particulates (e.g. partially incinerated sawdust) or leadfumes from metal casting.

The domestic sector also contributes to lower air quality.The use of wood heaters has increased significantly sincethe late 1970s to the stage where roughly two out of threehomes use firewood as their main heating fuel. The com-bined effect of thousands of heaters within a single airshedhas led to unacceptable concentrations of fine particulatesin some weather conditions (see Case Study 4), eventhough each house contributes relatively small amounts ofpollution. But even the pollution from a single heater orbackyard incinerator can cause localised pollution becauseof the close proximity of neighbours in urban areas.Indicator theme: Particulate pollution levels in population centres

In rural areas, aerial spraying of crops or plantations is thecause of occasional air quality problems. Odours fromsome agricultural activities may also be a source of com-plaint. Smoke from hazard-reduction burning and wildfires can decrease air quality over large areas, but usuallyonly for short periods.Indicator theme: Number of air quality complaints received by Environment

Tasmania

ATMOSPHERE 1.21

FIGURE 19: CADMIUM AND ZINC IN ZINC-REFINERY DUST FALLOUT, HOBART

Micrograms of metal deposited per square metre per day.Source: ENVIRONMENT TASMANIA

Cad

miu

m (

µg/

m2/

day)

Zin

c (µ

g/m

2/

day)

1000

2000

3000

1985 1986 1987 1988 1989 1990 1991 1992 1993 1994

Cadmium

Zinc

4

8

12

FIGURE 20: LEAD AS SUSPENDED PARTICULATEMATTER IN MOONAH

Micrograms per cubic metre averaged over a 24 hour collection

period. Source: ENVIRONMENT TASMANIA

1982 1984 1986 1988 1990 1992

1.0

2.0

Lead

(µg

/m

3)

CASE STUDY 4: AIR QUALITY STUDIES:LAUNCESTON, HOBART AND TAMARVALLEY

LAUNCESTONThe Launceston air quality study,

which ran from mid-1992 to the end

of 1994, is the most intensive study

carried out in the State (Air Pollution,

Environmental Health & Respiratory

Diseases Working Party 1996). Total

suspended particulates were measured at five sites across

the city, and local meteorological conditions recorded. The

particulates were analysed for a range of metals and organic

components. Links between days of high pollution and

reports of respiratory problems were also examined. The

study was particularly aimed at establishing the causes of

obvious air pollution incidents in winter.

Results showed that there is significant and potentially

serious air pollution during winter. There is also evidence of

increased acute respiratory disese since 1980, particularly

during winter, which corresponds to the period when local

air pollution has been observed to have worsened.

Particulate pollution was the biggest concern, with some

measurements found to exceed levels recommended to the

Victorian Environment Protection Authority. Photochemical

air pollution was not found to be a problem.

The main source of particulate pollution (Figure 21) was the

combustion of wood, principally from the use of the more

than 24 000 domestic slow combustion heaters in

Launceston and the upper Tamar Valley. In the area, 65–70%

of homes use slow combustion heaters. In other states, the

highest proportion reported has been 26%.

Among the recommendations of the Report were that: there

be concerted education programs about heater operation

before each winter; continued monitoring of air pollution;

and that legislation improve heater emission limits and

improve building guidelines to include better insulation.

HOBARTA less ambitious study of wood-smoke was carried out in

Hobart at the University of Tasmania (Usman 1989). It

showed the extent to which air quality deteriorates in winter

in an urban area (Figure 22). During the winter months,

most of the suspended particulate matter in the air was very

fine particles (88% of the suspended particulate matter, by

weight, was less than 10 µm in diameter), whereas in spring

there was a smaller proportion of such particles (74%).

Pollution levels were worst in the evenings and mornings

(Figure 23). These are times when people refuel their wood

heaters and traffic flow peaks. As well as showing the

variability over time of different pollution sources, the study

illustrates the complex combination of these with different

meteorological conditions, which strongly influence

dispersion of the pollutants.

The annual average concentration of suspended particulate

matter of around 50 µg/m3, while far from ideal compared to

clean air, is well below that of many cities, such as New

Delhi (400 µg/m3), Bangkok (200 µg/m3), or Chicago

(100 µg/m3). But they are well above the clean-air

background levels of 0.05–0.1 µg/m3 at Cape Grim, where

the air being sampled is free of any localised pollution

sources. Such air provides a ‘baseline’ against which other

air can be measured.

TAMAR VALLEYAnother regional air quality study is underway for the whole

Tamar Valley airshed (which includes Launceston). This is

aimed primarily at establishing, through meteorological

measurement and computer modelling, how air pollution is

dispersed in the area, so that appropriate controls can be

placed on industries in the developing Bell Bay Industrial

Zone. The study has applied a three-dimensional diagnostic

wind-field model driving a gaussian puff-dispersion model

(Map 8). When used with the emissions inventory (made as

part of the study), it will improve predictions of the impacts

of new and existing industries or pollution control measures.

ATMOSPHERE 1.22

FIGURE 22: TOTAL SUSPENDED PARTICULATES INSANDY BAY

Micrograms per cubic metre averaged over a 24 hour collectionperiod.

Source: USMAN 1989

TSP

(µg

/m

3)

Jul Aug Sep Oct Nov0

20

40

60

80

100

120

140

160

Jun

Par

ticu

late

s (µ

g/m

3)

Winter1991

Summer1991

Winter1992

Summer1993

Winter1993

0

120

240

Maximum recommended24 hour average

FIGURE 21: TOTAL SUSPENDED PARTICULATES INLAUNCESTON

Source: AIR POLLUTION, ENVIRONMENTAL HEALTH & RESPIRATORYDISEASES WORKING PARTY 1996

3 6 9 12 15 18 21 24

Soil

ing

Inde

x (C

OH

/km

)

0

2

4

6

8

Hour of day

July

October

FIGURE 23: SMOKE CONCENTRATIONS IN SANDYBAY

For July and October 1987 expressed as the soiling index orcoefficient of haze per kilometre for hourly measurements.

Source: USMAN 1989

ATMOSPHERE 1.23

MAP 8: MATHEMATICAL MODELLING OF WOODSMOKEPOLLUTION IN THE TAMAR VALLEY

Accumulation and dispersion of oxides of nitrogen from woodsmoke at

(a) 8 a.m. and (b) 11 p.m. in typical calm winter conditions.Source: MICHAEL POWER

45.0 - 49.9

40.0 - 44.9

35.0 - 39.9

30.0 - 34.9

25.0 - 29.9

20.0 - 24.9

15.0 - 19.9

10.0 - 14.9

5.0 - 9.9

4.0 - 4.9

3.0 - 3.9

2.0 - 2.9

< 1.9

NO x (µg/m3)

Kilometres

0 5 10

CASE STUDY 5: SMOG BUSTERS

PRESSUREAir pollution is the key

environmental issue to Australians

(Australian Bureau of Statistics 1996).

Community pressure groups, and the

Australian Medical Association, have

released high-profile reports linking air

pollution (particularly vehicle-related air

pollution) to adverse health effects. University and medical

researchers have frequently called on the Commonwealth

Government to act on these findings and to reduce air

pollution as a matter of urgency. Conservation organisations

have continually lobbied the Commonwealth Government for

national strategies to combat air pollution and the enhanced

greenhouse effect.

STATEThe magnitude of the problem requires action at every level—

Commonwealth, state and local. Legislation and economic

incentives have only a limited effect and community activism,

whilst reinforcing attitudes about the gravity of the air-

pollution problem, has not so far changed community and

individual behaviour. Motor vehicles are a major contributor to

air pollution in large urban areas in Australia, and a major

shift in the current trend of increasing car use is needed if

the problem is to be tackled successfully. Cars are an

ingrained part of the Australian culture and, for so long as

public transport is perceived as inconvenient and inefficient,

dependency on personal vehicles will be difficult to

counteract.

RESPONSEPart of the Commonwealth Government’s response to the

problem of air pollution has been to establish Federal Air

Quality Objectives, which focus the issue. Also, recognising

the importance of community action in generating change,

the Commonwealth Government, through its Environmental

Protection Agency, has responded to the problem of

increasing car use and its resultant detrimental effects on air

quality by providing $516 000 to the Smog Busters network.

The network, coordinated by Environment Victoria and

managed by corresponding conservation organisations

throughout Australia, has the following objectives:

• to raise community awareness of pollution issues arising

from motor vehicle emissions

• to mobilise community resources to promote increased

availability and use of public transport in a selected road

corridor

• to test the effectiveness of community action as a means

of promoting the Commonwealth Government’s air quality

objectives.

In Tasmania, the Smog Busters Project Officer, working with

the Tasmanian Conservation Trust, is focusing on the Main

Road corridor from Glenorchy to the Hobart Central Business

District. The specific objectives are:

• to promote greater awareness of the problems of air quality

through initiating a community air-monitoring project called

Airwatch, developed by CSIRO

• through liaison with the Metropolitan Transport Trust and

the Hobart and Glenorchy city councils, to raise the quality

and profile of public transport services along the corridor

• to encourage increased use of public transport along the

corridor.

a

b

Responses to poor air qualityCommunities become concerned when pollutants reachunacceptable levels. Wood-smoke and odours are exampleswhere pressure to reduce emissions of pollutants has comelargely from the community. These pollutants are visible orcan be smelled, so sophisticated analyses are not needed toconvince people who are directly affected that the pollu-tion must be reduced. Other pollutants, such as lead orother heavy metals, are less obvious to the community, soresponses are triggered more by scientific concerns linkedto health risks. In both cases, the response itself mightrange from government legislation forcing reduced emis-sions to self-regulation or changed behaviour by thoseresponsible for the pollution.

Targeting certain areas for intensive study, with detailedexamination of a range of pollutants, is the most effectivemeans of identifing pollutants that might otherwise goundetected. Case Study 4 indicates the type of monitoringrequired. Similar programs are required in other airshedsin the State (e.g. Case Study 5).

Simply identifying some activity as the cause of lowered airquality may be sufficient to solve a problem, but moreoften there is debate over whether a particular pollutant isa proven risk to health in the concentrations beingobserved. This usually means compromise and gradualimprovement governed by economic and technical consid-erations.

Some of the follies of the past, such as the poor air qualityin Queenstown during the early part of this century, areunlikely to be repeated because of much greater commu-nity awareness and stricter controls over emissions.However, it is sobering to reflect on the destructive poten-tial of serious air pollution episodes, as illustrated by thefollowing extract from Geoffrey Blainey’s book on miningat Queenstown:

In still weather sulphur from the smelters thickened fogsinto pea-soupers, choked Queenstown, and blanketed thevalley … Men who set out with hurricane lamps for thesmelters in the morning were sometimes found milesaway at evening. Sulphur was in every breath of air;even tobacco lost its taste … Sulphur, rain and firepainted a new landscape. Fogs heavily charged with sul-

phur made green grass and plants yellow in a day … Nofresh vegetation grew … Early in this century the land-scape was black and desolate, a cemetery of blackstumps. Two beautiful valleys had become as ugly as bat-tlefields. (Blainey 1967, pp. 99–101)

It is only now that vegetation is starting to return to thebare hills of Queenstown. The air pollution ceased inQueenstown when the sulfur-producing smelters wereclosed down in 1922, although mining and ore-concentrat-ing, which polluted water, continued. This is an example ofsolving an air-pollution problem by simply closing downthe source, even though the indirect effects have lingeredfor many years (see also Case Study 1, p. 6.5 and CaseStudy 2, p. 8.8).

An example of gradual improvement in air quality is illus-trated in Figure 20 which shows lead concentrations in air,collected as suspended particulates, in a busy suburbanarea of Hobart from 1981 to 1993. The large daily andannual fluctuations are a result of changes in dispersion,with winter conditions giving rise to an accumulation oflead in the atmosphere. But since the late 1980s there hasbeen a downward trend as more and more vehicles useunleaded petrol. The lack of regular measurement makesprecise calculation of these trends difficult. Nevertheless, itis of some concern that lead concentrations are as high asthose measured in central Sydney.

Indoor airIn the last few decades, attention and concern aboutindoor air quality and its adverse health effects have beenincreasingly expressed. This concern was due largely to therecognition of ‘Sick Building Syndrome’; a deterioration ofhealth and general well-being, and a loss of productivity,that results from exposure to poor-quality air inside build-ings. However, outbreaks of Legionnaires disease and theproblems caused by asbestos dust have also served to focusattention on the indoor environment.

Indoor air quality is important, as we spend most of ourtime indoors; in industrialised nations, anywhere between70–90%. Therefore the physical micro-environmentindoors is an important factor in the provision of good, orat least satisfactory, conditions for human life.

ATMOSPHERE 1.24

TABLE 7: SIGNIFICANT INDOOR AIR POLLUTANTS

Volatile organic compounds These include aliphatic and aromatic hydrocarbons, chlorinated hydrocarbons, and

various ketones and aldehydes; some may be carcinogens.

Formaldehyde Of the volatile organic compounds, formaldehyde is especially common. It is found in

many synthetic resins used as adhesives in making particle board, in paper products, and

in making foams for thermal insulation.

Tobacco smoke The burning of tobacco products is a source of a great number of indoor contaminants,

including a complex mixture of gases, vapours and particulate matter.

Asbestos and fibrous particles Asbestos has been most widely used commercially. It was also in many building

products, e.g. insulation, cement pipe and sheet.

Ozone Ozone is a pulmonary irritant that affects the mucous membranes, other lung tissues,

and respiratory function. Indoor sources include copying machines, electrostatic

cleaners, and vehicle exhaust in garages.

Radon Radon-222 is a radioactive ‘noble gas’, the decay product of radium-226. It is present in

most soils, rocks and masonry building materials, but more common in some.

Viable particulate matter Pollen, bacteria, viruses, and fungal and plant spores are significant contributors to

airborne particulates. Such particulates have transmitted diseases such as Legionnaires

disease to building occupants via ventilation systems.

In addition, efforts to improve the energy efficiency ofcommercial and residential buildings by decreasing airexchange with the outside air may result in unacceptableexposure to some pollutants.

Pollutants in one building may be quite different fromthose in another, depending on the building’s construc-tion, fittings, usage and ventilation system. Because ofthese highly variable usage and micro-environmental fac-tors, human exposure to indoor air pollution is difficult toquantify. The main pollutants present in the indoor envi-ronment are given in Table 7, although manufacturing andindustrial sites can have a number of other substances thatcan cause problems.

Health effectsEnvironments polluted by harmful substances, whetherindoors or outdoors, may directly threaten health, shortenworking lives, increase accident rates or reduce productiv-ity. Some of the most publicised health effects resultingfrom the indoor environment come from exposure toasbestos dust, particularly during the renovation or mainte-nance of older industrial and commercial buildings.Outbreaks of Legionnaires disease have also generatedwidespread concern. The Legionella bacteria can multiplyrapidly in warm, moist environments such as those foundin air conditioning systems.

Sick Building Syndrome is much more subtle, and isunusual in that it is characterised by an increased preva-lence of non-specific symptoms. Buildings are said to be‘sick’ if the prevalence of mucous-membrane irritation orgeneral symptoms exceeds 20% within a fairly large groupof people. This general measure is used throughout thewestern world.

The symptoms, though not specific in isolation, form arecognisable pattern that has been repeatedly observed inconnection with Sick Building Syndrome. The symptomsgenerally begin slowly and then progress, with most peoplereporting relief of symptoms on leaving the indoor envi-ronment or workplace and a recurrence on re-entry. Themost common symptoms are eye irritation, irritation of the

mucous membranes of the nose and throat, lethargy andheadache.

Such indoor exposures will cause, at least for a small pro-portion of people, susceptibility to diseases, worsening ofexisting diseases, or sensitisation with or without other dis-eases. If this discomfort decreased productivity by only 1%,the cost to society would be significant; this cost wouldoften exceed that of remedial measures to improve theindoor air quality. Unfortunately, there is still not enoughinformation on the full extent of the effect on health ofindoor air pollutants.

Monitoring of indoor air qualityThe effects of indoor pollution on health can be assessedby several methods, most of which are quite cumbersomeand time-consuming. Furthermore, connections betweenthe indoor environment and illnesses may prove difficultto quantify.

The most straightforward way to measure the effects ofindoor air quality in the workplace is to monitor the num-ber of sick days taken due to workplace air qualityproblems, and the overall health of people while indoors.Indicator theme: Number of sick days taken due to workplace air quality

problems

Initial analyses of both absenteeism and sickness levels canbe through a questionnaire that addresses symptomologyand workplace/illness association. This method is good foran overview of the health of employees.

This can then be followed by biological monitoring, suchas aromatic/aliphatic hydrocarbon blood tests before, dur-ing and after entering the workplace. This needs to be donein conjunction with a medical diagnosis of the illness anda test analysing an individual’s sensitivity to chemical andbiological allergens (e.g. sublingual drops, Radio AllergoSorbent Test).

The accuracy of symptom analyses is improved whenchemical, physical, biological and psychological monitor-ing methods are combined. This is vital when trying toestablish a strong cause-and-effect relationship betweensymptoms and the indoor environment.

ATMOSPHERE 1.25

FIGURE 24: SICK BUILDING SYNDROME IN HOBART, CLARENCE AND GLENORCHY

Source: MESAROS 1995

Occ

upa

nts

wit

h S

BS

sym

ptom

s (%

)

Buildings in study

10

20

30

40

50

60

70

80

90

100

ATMOSPHERE 1.26

Indoor air quality in TasmaniaVery few studies have been made into the indoor air qualityin Tasmania. A recent study of 61 office buildings and 668employees in Hobart, Clarence and Glenorchy identified alarge number of buildings as ‘sick’ (Mesaros 1995). Thestudy also confirmed a high level of occupant discomfortand a significant loss of productivity.

Most of the buildings had a significant number of theoccupants reporting one or more typical Sick BuildingSyndrome symptoms (Figure 24). Of these occupants, 68%stated that symptoms ceased gradually after leaving theworkplace, and 66% that symptoms recurred when they re-entered. One third of the buildings even exceeded the 20%‘sick’ level when it was increased from occupants havingonly one, to more than six, of the 13 possible Sick BuildingSyndrome symptoms. However, it is difficult to assess theTasmanian situation, as comparable studies have not beencarried out in the rest of Australia. But further investigationof indoor air quality is clearly necessary. It is likely that thepresent standards and criteria for building design and test-ing of indoor air quality will need revision.

Nevertheless, the reasons for such disturbing results areunclear, and probably include a variety of factors. Many ofthe toxins are derived from construction and furnishingproducts. Tasmanian buildings often have a relatively highusage of synthetic materials, for instance in carpets, gluesand paints. The solvents used in many cleaning productsalso contribute to the level of environmental toxins.

The method of heating can also add to the deterioration ofindoor air quality. For example, the prevalence of woodfires in Tasmania is a significant contributor to particulatepollution, while underfloor heating can increase theamount of gases given off by floor glues and carpets. ManyTasmanian homes are also not insulated—25% comparedwith 15% in Victoria and South Australia (AustralianBureau of Statistics 1996). This means that more heating isrequired to keep buildings at a comfortable temperature,which could be the cause of more pollutants being addedto the indoor environment.

Much of the problem could be alleviated through greaterawareness. Recognition of the potential sources of indoorpollutants allows people to choose products and buildingdesigns, and modify their behaviour, so that the accumula-tion of pollutants is reduced.

ConclusionsMeasurements at Cape Grim show that the air blowingover Tasmania is some of the cleanest in the world.However, studies have shown that there are some localareas in Tasmania that have poor air quality. In particular,air quality around urban and industrial areas can be poor,especially in winter when the climatic conditions experi-enced enhance the localised build up of pollutants. Similarproblems are experienced indoors. Moves to seal houses toimprove heating efficiency without ensuring adequate ven-tilation may lead to a build up of pollutants.

Pollutants can come from a variety of sources, and manycome from activities that are undertaken as a part of nor-mal daily life. For example, domestic wood heaters andvehicles are a source of many pollutants. Minimisng theiremissions will help to provide a much healthier andcleaner environment.

There are also larger scale problems that are much lessobvious. The effects of climate change and ozone depletioncould have widespread ramifications to human and ecosys-tem health, biodiversity, agricultural productivity and soon. The precautionary principle is guiding the introductionof many control measures while atmospheric models arecontinually being refined to determine the exact nature ofthe changes that could be expected.

Indicators can be used to keep track of the complex andvariable nature of the atmosphere. Particularly at the locallevel, indicators can provide an early warning system forproblems like the build up pollution. Actions can then betaken before the problem becomes a serious threat.

All actions that are taken help to provide a cleaner atmo-sphere. When added up, improvements at the local scale inmany places mean an improvement at the global scale.

ContributorsAlan Bennett Environment Tasmania

Martin Bicevskis Department of Communityand Health Services

David Campin Australian Paper

Frank Carnovale Environment Tasmania

Frank Cattell Environment Tasmania

Chad Dick Cape Grim Baseline AirPollution Station

Richard Hammond Environment Tasmania

Sam Hanslow Environment Tasmania

Rowena Evans Department of Environmentand Land Management

Desiree Mesaros University of Tasmania

Stuart Newman Consultant

Manuel Nunez University of Tasmania

Michael Power University of Tasmania

Helen Pryor Tasmanian Conservation Trust

Andrew Scanlon Hydro-Electric Commission

Doug Shepherd Bureau of Meteorology

John Todd Eco-Energy Options

Peter Walford Cape Grim Baseline AirPollution Station

Alasdair Wells Department of Environmentand Land Management

State of the Environment UnitAlasdair Wells (editorial coordinator), Stephen Waight,Rowena Evans

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