Concerns for Health from Smog and Heat

Presentation to Smog Workshop

for Ontario Medical Officers of Health

Convened by Clean Air Partnership and

Ontario Medical Association

Dr. David McKeown

February 2006

• People can spend a lot of time close to pollution sources

Health Effects of Air Pollution

• More and longer lasting respiratory symptoms

• Reduced lung function • More bronchitis and

asthma attacks• More emergency room

visits• More lung cancer and

heart attacks• More hospitalizations &

early deaths

Burden of Illness Estimates – How Many People Are Affected?• Is a form of risk assessment• Applies risk coefficients from existing

epidemiological studies worldwide• Uses community-specific data on daily

pollution levels• Uses community-specific data on

adverse health outcomes such as hospitalizations and mortality (e.g. for respiratory and cardiac causes)

Air Pollution Burden of Illness – Toronto (2004)

• 1,700 premature deaths/year • 6,000 hospitalizations/year • Would likely not have occurred when

they did without exposure to air pollution• Preventable • Increases severity or frequency of

common medical conditions and illnesses• Created comprehensive agenda for

provincial action to improve air quality

Pyramid of Health EffectsToronto Annual Estimates for Inhalable Particulates

(PM10)

Premature mortality (acute)177

Cardiovascular hospitalization421

Respiratory hospitalizations597

Adult chronic bronchitis 1,186

Emergency room visits 5,981

Bronchitis in children

11,997

Asthma symptom days 71,930

Air pollution makes asthma worse

Comparison of Illness Estimates for Toronto from Air Pollution

InvestigatorYear

PublishedData

PeriodAnnual

MortalityAnnual

Hospitalization

TorontoPublicHealth

2004 1999 1,700 6,000

HealthCanada

20051998 to

20001,840 ----

OntarioMedicalAssociation

2005 2005 1,450 3,980

Air Quality Benefits Assessment Tool (AQBAT)

• Computer simulation tool developed by Health Canada

• Estimates human health benefits or impacts from changesin air quality

• Pollutants – CO, NO2, O3, SO2, PM2.5, PM10

• Health Endpoints

– Mortality (acute and chronic) – Acute respiratory symptom days – Chronic bronchitis – Cancer – Cardiac and respiration hospitalizations – Emergency room visits – Restricted activity days

Smog and Heat Problems Compounded in Cities

Urban Populations at Increased Risk

• Vehicles and people are in close proximity

• Canyon effect of buildings traps pollutants

• Urban heat island effect

• Roads contribute to heat retention in cities

• Local emissions compound transboundary pollution

• Elevated exposures during commuting (whether walking, cycling, waiting streetside for transit, or inside a vehicle in stagnant traffic)

Climate Change is Happening

• Green House gas (GHG) emissions increasing in Canada

• Mean global temperature increased about 0.6C in last 100 years (1C in Canada)

• Mean global temperatures expected to increase about 3 C this century

• Kyoto Protocol - reduce GHG by 6% below 1990 levels by 2010

• Kyoto Protocol delays doubling CO2 levels by about 15 years

Temperature Trend

Today

Source: Environment Canada

Today

Tem

per

atu

re C

han

ge

Health Concerns with Extreme Heat

• Death occurs when core body temperature rises 5 C

• Seniors and infants at increased risk due to reduced capacity for temperature regulation

• Contributory factors include high blood pressure, obesity, physical inactivity, medication use

• about 10,000 Americans died due to oppressive heat in summer 1980

• about 11,000 Europeans died from heat in summer 2003

Major Study Undertaken(Toronto Public Health, Environment Canada

and Health Canada)

• What are the combined effects of weather and air pollution?

• What can we expect in the future?

• How can we improve the heat warning system?

Key Findings - Historical Analysis

• Heat-related mortality significantly higher for seniors and those with cardiovascular illness than others

• On those days with extreme heat, average daily mortality about twice as high as for comfortable days

Key Findings - Historical Analysis

• On average (for period 1954 - 2000), of the acute deaths each year in Toronto:– 120 were heat-related– 105 cold-related– 822 were air pollution-related

• About 20% mortality associated with extreme temperature and 80% with air pollution

Distribution in Mean Annual MortalityAttributable to Extreme Temperatures and Air

Pollution

11

9

11

12

10

12

13

10

79

79

76

78

0% 20% 40% 60% 80% 100%

Windsor

Ottawa

Montreal

Toronto

% of Annual Mortality

Heat-related

Cold-related

Air pollution-related

Key Findings - Projections for Future

• Based on average of five climate change scenarios and current air emissions remaining constant, the study projects:– heat-related mortality will double by 2050 and

triple by 2080– air-pollution related mortality will increase by

20% in 2050 and 25% in 2080, largely because of increased ozone levels from global warming

• Global warming will make air pollution problems worse

Public Warning Systems

• Air Quality Index (AQI) - smog advisory issued by OMOE when AQI predicted to be 50 or greater (regional and persistent)

• Heat Health Alert system- alerts issued by Toronto Public Health (other Canadian cities exploring similar system)– Extreme Heat Alert - greater than 90%

chance of heat-related excess mortality

– Heat Alert - greater than 65% chance of heat-related excess mortality

Ontario Air Quality Index (AQI)

AQI Scale Category

0 - 15

16 - 31

32 - 49

50 - 99

100+

Very Good

Good

Moderate

Poor

Very Poor

Smog Alert

Incr

easi

ng

seve

rity

of

hea

lth

ef

fect

s At AQI = 50, OMOEcalls Air Quality Advisory

Smog Alert Days in Toronto

In 2005, Toronto experienced 48 smog alert days

15

10

35 7

9

3

20 18

1214

48

0

10

20

30

40

50

60

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Num

ber o

f Day

s

Diurnal fluctuation in hourly pollutant levels (Toronto, 1997-2000)

Toronto NO2 (1997-2000)

10

15

20

25

30

35

40

45

01 03 05 07 09 11 13 15 17 19 21 23

Hour

Co

nc

en

tra

tio

n

(pp

b)

.

Days with AQI >=50

Days with AQI <50

Toronto O3 (1997-2000)

0

10

20

30

40

50

60

70

80

01 03 05 07 09 11 13 15 17 19 21 23

Hour

Co

nc

en

tra

tio

n (

pp

b)

. Days with AQI >=50

Days with AQI <50

Diurnal fluctuation in hourly pollutant levels (Toronto, 1997-2000)

Toronto PM10 (1997-2000)

0

10

20

30

40

50

60

01 03 05 07 09 11 13 15 17 19 21 23

Hour

Co

nc

en

tra

tio

n (

ug

/m3)

Days with AQI >=50

Days with AQI <50

Toronto PM2.5 (1997-2000)

0

5

10

15

20

25

30

35

01 03 05 07 09 11 13 15 17 19 21 23

Hour

Co

nc

en

tra

tio

n (

ug

/m3)

Days with AQI >=50

Days with AQI <50

Guidance Regarding Physical Activity and Air Pollution

• Be physically active outdoors• Reduce intensity of outdoor activity at

AQI levels that trigger symptoms or when AQI exceeds 50

• To reduce exposure, plan strenuous activity such as running or jogging before morning rush hour and in low traffic areas

Proposed National Air Quality Health Index (AQHI)

Percent of days at low, moderate, high or very high health risk levels, 2001

AQHI Level Vancouver Hamilton Toronto Montreal

Low health risk

0-384 33 36 43

Moderate health risk

4-516 46 47 44

High health risk

6-101 20 16 13

Very high health risk

Over 100 0 1 0

Source: With permission from Dr. Dave Stieb, Health Canada

Heat Alert Days in Toronto

In 2005, Toronto has experienced 26 heat alert days of which 18 were in the extreme heat category

Heat Alerts 2001-05

6

14

3 2 8

3

2

3 0

18

05

1015202530

2001 2002 2003 2004 2005

Year

Nu

mb

er o

f Day

s

Extreme heat alert

Heat alert

Fluctuations in Frequency of Hot Weather Days in Toronto

(1954 to 2000)

0

1 0

2 0

3 0

4 0

5 0

6 0

7 0

1 9 5 4 1 9 5 9 1 9 6 4 1 9 6 9 1 9 7 4 1 9 7 9 1 9 8 4 1 9 8 9 1 9 9 4 1 9 9 9

Y e a r

Fre

quen

cy o

f H

ot W

eath

er

Eve

nts

3 : 0 0 p . m . T e m p e r a t u r e ≥ 3 0 ° C

H o t W e a t h e r T y p e s

Conclusions

• Air pollution continues to pose considerable health risk

• Global warming makes air pollution and its impacts worse

• Public health sector can catalyze and support reduction in emissions of air pollutants and greenhouse gases

• Heat and smog alert warning systems help individuals take personal precautions