The problem (and opportunity) of Air

Quality in CitiesProf. Paul S. Monks

Nitrogen dioxide (NO2) is an important ingredient in the formation of air pollution. This map shows the global distribution of tropospheric NO2 as observed from 2005 to 2008 by the Ozone Monitoring Instrument (OMI). Various sources of air pollution can clearly be distinguished: traffic, heavy industry, fossil fuel power plants, biomass burning, oil refineries, and shipping routes. OMI was built by The Netherlands and Finland and is onboard NASA's Aura satellite.

Paris

Biomass burning

JohannesburgHighveld area

Buenos AIres

Mexico City

China’s industrialprovinces

Po valley

Shipping routes

São Paulo

Santiago

Moscow

WesternEurope

Riyadh

Oil sandsproduction

Melbourne

Sydney

Urumqi

Air pollution

low NO2 high NO2

Powerplants

New Delhi

U.S. East coastSan Fransisco

Los Angeles

Cairo

Pearl river delta

TokyoTehran

Chicago

more data and information can be found at www.temis.nl

Air Quality

“Around 90 % of city dwellers in the European Union (EU) are exposed to one of the most damaging air pollutants at levels deemed harmful to health by the World Health Organisation”

European Environment Agency (October 2013)

AQEG, London, March 2010 4

What is the impact of Air Quality?

AQ has implications for a number of contemporary issues including:Human health,

(e.g. respiratory, cancer, allergies…),

Eco systems (e.g. crop yields, acidification / eutrophication of natural ecosystems),

National heritage (e.g. buildings),

Regional climate (aerosol and ozone exhibit a strong regionality in climate forcing).

AQ - What are the major components?

The Urban Population Exposure

The ISSUE, Feb14 7

The Chains of AQ

POLICYIMPACTSe.g.health

OBSERVATIONSEMISSIONS

Where are we now?

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a) Emission Trend (total UK)

Air Pollution: Action in a Changing Climate; March 2010

b) Birmingham centre

The ISSUE, Feb14

Rural Background - Trends

The Issue, Feb 14 10

Zoe Fleming (ULeic)Weybourne, N. Norfolk.

Some AQ Topics in Brief

The ISSUE, Feb14 11

Particles

Leicester, 23/5/2013-5/6/2013

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High PM2.5 concentrations are frequently associated with air transported into the UK from continental Europe.

Urban background PM2.5 concentrations are dominated by regional rather than local sources, PM from sources in continental Europe, probably as secondary PM, significantly affects concentrations in the UK.

A transect ...

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Easting (m)

Annual mean PM2.5 transect across London for 2009 from PCM model

traffic area sources

non-traffic area sources

point sources

urban dust

rural dust

regional primary

secondary organic

secondary inorganic

residual

sea salt

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Wood Smoke

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BC

Prevalence of wood burning increasing, (re-)emergent issue in terms of AQ & health

Changing emissions and ozone

The Issue, Feb 14 16

Difference map for O3 concentrations (units are g m-3) in Paris change with zeroed out traffic emissions (Pandis et al., 2010).

Change in ozone 2008-1998 in UK (Summer) (VonSchneidemesser et al, 2014)

Aerosols and other AQ agents on climate17

Air Quality “regulated?” aerosols are the largest factors offsetting greenhouse gas forcing!

‘AIR QUALITY’ ‘CLIMATE’HaloCarbs

TropO3

BlackCarbon

Aerosols(direct + indirect)

CO2 CH4N4O

“AQ”

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Parsing out the forcing agents

• Could climate goals be achieved, at least partially, by non-climate treaties?

• Factors other than climate are also of major concerns regarding these forcing agents

• AQ and climate policies & their impacts need to be examined together and based on sound scientific knowledge

Ravishankara (NOAA)

AQ or Climate

Mitigation of Short-Lived Climate Forcers

The ISSUE, Feb14 19Shindell et al, 335, 183 Science, 2012

Trade-Offs

20VonSchneidermesser and Monks, ESPI,15, 1315, 2013

Seven Facts from the 2013 “Year of the Air” (EEA)

1. More than 9 out of 10 city-dwellers in Europe are exposed to air pollutants above World Health Organisation guidelines

2. Air pollution legislation is not always fully implemented3. Cutting air pollution may also help address climate change 4. In 2011, several EU Member States breached legal limits for

air pollution, mostly for nitrogen oxides (NOx). Traffic is one of the main sources of NOx.

5. A growing body of scientific evidence suggests air pollution is more harmful than previously thought.

6. Air pollution also has an economic cost to society.7. Many cities are taking positive steps to cut air pollution.

Summary

• Air pollution harms human health and the environment

• Much success in reduction of emissions and general improvement in air quality in Europe.

• The air quality problem persists especially in cities

• Many of the pollutants have a complex regional and local interplay– PM2.5, NO2 and ozone (hemispheric)

The ISSUE, Feb14 22

THE ISSUE Workshop on Air Quality in Cities

M. Petrelli - Roma Tre University

February 2014

The evaluation of road traffic emissions

1. Model for emissions estimation in large scale urban network• Urban network congestion• Large scale city (not single arterial)• with relatively low calibration & computational cost/time• taking into account different time slices (time variability)• taking into account queue phenomena

2. Evaluation of traffic management impacts from emissions point of view• Traffic management such as arterial signal optimization (cycle,

phases, offset), ramp metering, one-way system, reversible lanes, ITS solutions and so on……

• optimum for traffic (generalized cost/time) ≠ optimum for emissions

• Real time estimation

Which evaluation and why……….

State of the Art

Two main approaches:

• Microscopic (USA)based on the evaluation of driving phases of a vehicle (acceleration, steady state, deceleration)

• Macroscopic (EU)based on computation of specific vehicle emission factors, average vehicles speed and distance travelled

1) Macroscopic model based on v, k, q (CORINAIR)• reference model for estimating emissions in

Europe[Lumbreras et al.; European Environment Agency]

• in congested network, usually macroscopic models underestimate emissions

[Shukla-Alam; Rakha-Ding; Rouphail et al.]

2) Microscopic model based on vi, a, d, delay (MOVES)• mainly useful for emission estimation in arterials

or single intersection[Stevanovic et al.]

• good results in arterial or single intersection optimization

[Midnet et al.; Coelho et al.; Rakha et al.]

Traffic model

(congestion)

Emission model

Dispersion model

Proposed approach

Estimation of pollutant emissions in a large area network with a suitable level of accuracy

Possible use of the model:

• Offline for planning

• Real Time for control

MICRO(approach)

MACRO(approach)

MESO(approach)

Mesoscopic:DTA (Dynamic Traffic Assignment)

Large area road network24 h analysis

Realistic emissions estimation

New Model for emission estimation

The idea is to divide each link in 3 different parts:• LA - vehicles are at free-flow speed• LB - vehicles are in queue• LC - vehicles are in acceleration phase

Post processor module:Model for queue assessment + Assessment of 3 different emission factors

• The model has been applied to the city of Brindisi (100K inhabitants)

• Traffic flows have been simulated from 5 am to 23 pm

• 884 links• 306 nodes• 14 signalized

intersection

Application in Brindisi network

Total daily CO emission at intersections

Application in Brindisi network

Level of congestion in the road network

Emissions comparison

Low congestion in the network – very similar emission values

Emissions comparison

Low congestion in one arteria – large difference in emission values

Emissions comparison

Low congestion in the network – very similar

emission values

Impact evaluation of different policies

VKT VHDAv.

Speed CO NOx PM10

a -   - -  - - -b -1% -5% 3% -2% -2% -2%c -2% -13% 7% -15% -11% -11%d 0% 0% -3% 0% 0% 0%

b+c -4% -19% 12% -14% -12% -11%b+c+d -3% -17% 10% -13% -11% -10%

Application in Eur Rome network

Application in Eur Rome network

High congestion in the network – large increase in emission values

Application in Eur Rome network

High congestion in the network – large

increase in emission values

Model Layout

• Meso-simulation model (Dynameq) has been used to evaluate traffic congestion and related traffic flow parameters

• CORINAIR has been used to evaluate the specific vehicle emissions

• Dispersion model has to be developed to estimate air pollutants dispersion

Need of dispersion model and data for model validation

Breakout Sessions

Optimal use of road traffic and travel data – Roland Leigh – Lecture Theatre

Promotion of multimodal journeys – Josh Van Hey – Bell Restaurant

Uptake of public transport – Marco Petrelli – Bell Restaurant

Improving emissions using alternative fuels – Teresa – Murdoch Room

Local Government Policy – Craig Brown – Brunel Room

Breakout Sessions

Feedback from breakout Sessions - Facilitators

Conclusions