Air pollution measurement, modelling and mitigation, third edition

Tai Lieu Chat Luong


Air Pollution

A one stop, comprehensive textbook, covering the three essential components of air pollution science. This third edition has been updated with the latest developments, especially the
inclusion of new information on the role of air pollutants in climate change. The authors give
greater coverage to the developing economies around the world where air pollution problems
are on the rise.
The third edition continues to cover a wide range of air quality issues, retaining a quantitative perspective. Topics covered include:
•
•
•
•
•
•

gaseous and particulate air pollutants
measurement techniques
meteorology and dispersion modelling
mobile sources
indoor air
effects on plants, materials, humans and animals.

Moving away from classical toxic air pollutants, there is a chapter on climate change and
another on the depletion of stratospheric ozone. A special feature of this new edition is the
inclusion of a fresh chapter on air pollution mitigation by vegetation, mainly its role in maintaining a sustainable urban environment.
The book is recommended for upper-level undergraduate and postgraduate courses specialising in air pollution, both for environmental scientists and engineers. The new material included
in this edition extends its usefulness for practitioners in consultancies or local authorities.
Abhishek Tiwary is a Chartered Scientist and a Chartered Environmentalist involved in issues
related to urban air pollution management and sustainable development. He is based at the

University of Newcastle, UK.
Jeremy Colls is Professor Emeritus in Atmospheric Environment at the University of Nottingham,
UK. He authored the previous two editions of Air Pollution.



Air Pollution

Measurement, modelling and mitigation
Third edition

Abhishek Tiwary and Jeremy Colls


First edition published 1997 by E. & F.N. Spon
Second edition published 2002 by Spon Press
This edition published 2010
by Routledge
2 Park Square, Milton Park, Abingdon, Oxon OX14 4RN
Simultaneously published in the USA and Canada
by Routledge
270 Madison Avenue, New York, NY 10016, USA
Routledge is an imprint of the Taylor & Francis Group, an informa business
This edition published in the Taylor & Francis e-Library, 2009.
To purchase your own copy of this or any of Taylor & Francis or Routledge’s
collection of thousands of eBooks please go to www.eBookstore.tandf.co.uk.
© 2010 Abhishek Tiwary and Jeremy Colls
All rights reserved. No part of this book may be reprinted or reproduced or utilised in any
form or by any electronic, mechanical, or other means, now known or hereafter invented,
including photocopying and recording, or in any information storage or retrieval system,

without permission in writing from the publishers.
This publication presents material of a broad scope and applicability. Despite stringent
efforts by all concerned in the publishing process, some typographical or editorial errors
may occur, and readers are encouraged to bring these to our attention where they
represent errors of substance. The publisher and author disclaim any liability, in whole
or in part, arising from information contained in this publication. The reader is urged to
consult with an appropriate licensed professional prior to taking any action or making any
interpretation that is within the realm of a licensed professional practice.
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
Library of Congress Cataloging-in-Publication Data
Tiwary, Abhishek.
Air pollution: measurement, modelling, and mitigation / Abhishek Tiwary and Jeremy Colls.—3rd ed.
p. cm.
Rev. ed. of: Air pollution / Jeremy Colls. 2002.
Includes bibliographical references and index.
1. Air—Pollution. I. Colls, Jeremy. II. Colls, Jeremy. Air pollution. III. Title.
TD883.A4713 2010
363.739’2—dc22
ISBN 0-203-87196-0 Master e-book ISBN

ISBN10: 0- 415-47933-9 (hbk)
ISBN10: 0- 415-47932-0 (pbk)
ISBN10: 0- 203-87196-0 (ebk)
ISBN13: 978-0- 415-47933-2 (hbk)
ISBN13: 978-0- 415-47932-5 (pbk)
ISBN13: 978-0- 203-87196-6 (ebk)

2009007820

To Our Family & Friends



Contents

Acronyms and abbreviations
Preface

xi
xix

1 Air pollutants: sources and control of gases
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9

1

Units for expressing pollutant concentration
The basic atmosphere 5
The vertical structure of the atmosphere 8
Anthropogenic emissions 11

Primary emission summary 35
Adsorption and absorption of gases 37
Other air pollutants 38
Secondary gaseous pollutants 43
Emission inventories 51

2

2 Air pollutants: particulates
2.1
2.2
2.3
2.4
2.5
2.6
2.7

Particle terminology 54
Particle size distributions 55
Aerosol mechanics 63
Particle sources 78
Abatement of primary particle emissions
Secondary particles 86
Trends in particle emissions 88

54

82

3 Mobile sources

3.1
3.2
3.3
3.4
3.5

91

Motor vehicle emissions 93
Train emissions 129
Shipping emissions 130
Aircraft emissions 131
Different modes of transport 137

4 Measurement of gases and particles
4.1
4.2

Methods of describing pollutant concentration
Sampling requirements 140

139
139


viii

Contents

4.3

4.4
4.5
4.6
4.7
4.8
4.9
4.10
4.11

Gas sampling 141
Gas concentration measurement 147
Quality control 157
Particle sampling 160
Particle measurement methods 162
Chemical composition of aerosol 175
Measurement of coarse particle deposition 178
Emission measurement from stationary sources 181
Measurement uncertainty 188

5 Concentrations and deposition
5.1
5.2
5.3
5.4
5.5
5.6
5.7

Gaseous pollutants 191
Patterns of occurrence 198

Particulate matter 205
Dry deposition of gases 207
Wet deposition 212
Total deposition and budgets 220
Analysis of an air pollution episode

191

221

6 Meteorology and modelling
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8

Meteorological factors 225
Dispersion models 237
Gaussian dispersion theory 238
Dispersion theory in practice 249
Dispersion of vehicle emissions and exposure modelling
Receptor models 258
Box models 259
Statistical models 260

7 Analysis of an air-quality data set

7.1
7.2
7.3
7.4
7.5
7.6
7.7

256

261

The raw data set 261
Period averages 264
Roses 265
Diurnal variations 267
Short-term events 270
Frequency distributions 271
Further statistical analyses 274

8 Indoor air quality
8.1
8.2
8.3
8.4

225

Building ventilation 276
Combustion 281

Indoor organics sources 284
Bioaerosols 286

275


Contents

8.5
8.6
8.7

Sick building syndrome 290
Odour and ventilation 291
Clean rooms 291

9 Mitigation of air pollution: the role of vegetation
9.1
9.2
9.3
9.4

Forest canopy intervention 294
Particle deposition to vegetation 299
Filter strips 301
Practical concerns of vegetation intervention

10 Effects on plants, visual range and materials
10.1
10.2

10.3

355

387

427

Ozone in the stratosphere 427
Destructive chemistry 433
The current situation 439
Ozone and ultraviolet 442
Clothing protection from UV 450

14 Standards and legislation
14.1
14.2
14.3
14.4
14.5
14.6

317

Our radiation environment 388
The role of gases 393
The role of aerosol 405
Gases and aerosol combined 410
Future scenarios 412
The main predictions 413

Feedbacks 420
Global responses 422

13 Ozone depletion and ultraviolet radiation
13.1
13.2
13.3
13.4
13.5

307

Responses of people 355
Effects on other animals 382

12 Greenhouse gases and climate change
12.1
12.2
12.3
12.4
12.5
12.6
12.7
12.8

293

Effects on plants 317
Visual range 344
Damage to materials 351

11 Responses of humans and other animals
11.1
11.2

ix

UK legislation 458
EU air-quality legislation 462
UNECE 464
World Health Organization (WHO) 466
EU industrial emission legislation 467
EU vehicle emissions 470

457


x

Contents

14.7
14.8
14.9
Index

US legislation 475
Legislation in the Asian region
Air pollution indices 486

483

489


Acronyms and abbreviations

AA
AAS
ACE
ACH
AES
ACGIH
AMIS
ANC
AOT40
APHEA
AQCD
AQI
AQMA
AQRV
AQS
ARN
AR4
AUN
BAF
BaP
BART
BATNEEC
BC

BCC
BFO
BPEO
BPM
BS
Btu
BTX

ambient air – usually refers to plants growing in the open for comparison
with those in chambers
atomic absorption spectroscopy
Aerosol Characterisation Experiment
air changes per hour – an estimator of building ventilation rate
atomic emission spectroscopy
American Conference of Government Industrial Hygienists
air management information system
acid neutralising capacity
accumulation over threshold – the measure currently favoured by
UNECE for estimating ozone impact on plants
Air Pollution and Health: A European Approach
Air Quality Criteria Document (US)
Air Quality Index
Air Quality Management Area (UK)
Air Quality Related Value (US)
Air Quality Standards (US)
Automated Rural Network
Assessment Report 4 – referred to the fourth assessment report of the
IPCC
Automated Urban Network
biological amplification factor – used to describe the overall response of

biological systems to ozone changes
benzo[a]pyrene
Best Available Retrofit Technology
Best Available Techniques (or Technology) not Entailing Excessive
Cost
black carbon
basal cell carcinoma
bunker fuel oil
Best Practicable Environmental Option
Best Practicable Means – the long-established UK philosophy for pollution control
British Standard
British thermal unit – unit of energy used in power, steam generation,
heating and air conditioning industries
benzene, toluene and xylene


xii

Acronyms and abbreviations

BUN
BVOC
CAA
CAAA
CAFE
CAI
CALINE
CARB
CCN
CE

CEC
CEH
CF
CFC
CFD
CHESS
CHP
CLRTAP
CNC
COH
COHb
COMEAP
COP
COPD
CORINAIR
CPB
CPC
CPCB
CPF
CRT
DALR
DALY
DDT
DEFRA
DEP
DERV
DI
DIAL
DMA
DME

Basic Urban Network – urban sites in the UK national network of
24-hour air pollutant samplers
biogenic volatile organic carbon
Clean Air Act (US)
Clean Air Act Amendments (US)
Clean Air for Europe
Clean Air Initiative – mainly used in the context of air pollution
in Asia
California Line Source Model – one of the most widely used dispersion
models for vehicle emissions
California Air Resources Board
cloud condensation nuclei – the particles on which condensation initially
occurs to form cloud droplets
collection efficiency
Commission of the European Communities
Centre for Ecology and Hydrology, UK
charcoal-filtered – an OTC supplied with cleaned air
chlorofluorocarbon – family of chemicals responsible for depleting ozone
in the stratosphere
computational fluid dynamics
Community Health and Surveillance System (US)
combined heat and power – used in the context of thermal energy
generation
Convention on the Long Range Transport of Air Pollutants
condensation nucleus counter
coefficient of haze
carboxyhaemoglobin – produced when blood haemoglobin absorbs CO
Committee on the Medical Effects of Air Pollutants (UK)
Conference of Parties (for UNFCCC)

chronic obstructive pulmonary disease
CORe Inventory of AIR emissions – the EU programme to collect and
map emissions data for all significant sources of eight gaseous pollutants
Canyon Plume Box Model for calculating dispersion in urban areas
condensation particle counter
Central Pollution Control Board (India)
clothing protection factor
continuously regenerating trap
dry adiabatic lapse rate – the rate of decrease of temperature with height
in the atmosphere applicable to a parcel of air that contains no liquid
water. Value 9.8 °C km–1
disability adjusted life years
dichloro-diphenyl-trichloroethane – one of the synthetic pesticides
Department for the Environment, Food and Rural Affairs (UK)
diesel exhaust particles
diesel engine road vehicle – diesel fuel used for road vehicles
direct injection
differential absorption LIDAR
differential mobility analyser
dimethyl ether


Acronyms and abbreviations

DMS
DOAS
DOC
DoE
DOM
DPF

DRAM
DTLR
DU
DVI
EA
EAA
EC
ECD
ECE
EDAX
EDU
EEA
EEC
EER
EESC
EF
EGR
EIONET
ELISA
ELPI
ELR
ELV
EMEP
ENSO
EPA
EPA
EPAQS
ERBS
ESP
ETC/AQ

ETS
EU
EUDC
EUROAIRNET
FACE
FAR

xiii

dimethyl sulphide – organic sulphur compound released from marine
phytoplankton that is eventually oxidised to sulphur dioxide and particulate sulphate in the atmosphere
differential optical absorption spectroscopy
diesel oxidation catalyst
Department of the Environment (UK)
dissolved organic matter
diesel particulate filter
direct-reading aerosol monitor
Department for Transport, Local Authorities and the Regions
(UK)
Dobson unit – for the column depth of ozone in the atmosphere
Dust Veil Index
Environment Agency (UK)
electrical aerosol analyser
European Community
electron capture detector
Economic Commission for Europe (same as UNECE)
energy dispersive analysis of X-rays
ethylenediurea – a chemical that protects plants from ozone
European Environment Agency
European Economic Community

erythemally effective radiation – sun-burning potential of a given radiation environment
equivalent effective stratospheric chlorine
emission factor – e.g. g km–1
exhaust gas recirculation
European Environmental Information and Observation Network
enzyme-linked immunosorbent assay
electrostatic low pressure impactor
environmental lapse rate – the vertical profile of temperature in the
atmosphere
emission limit value
European Monitoring and Evaluation Programme
El Niño Southern Oscillation
Environmental Protection Act (UK)
Environmental Protection Agency (USA)
Expert Panel on Air Quality Standards (UK)
Earth Radiation Budget Satellite
electrostatic precipitator
European Topic Centre on Air Quality
environmental tobacco smoke – the combination of MTS and STS that
makes up the atmospheric load
European Union
extra-urban drive cycle (EC)
European Air Quality Monitoring Network
Free-Air Carbon Dioxide Enrichment – the system developed in the US
for elevating the CO2 concentration above field crops
First Assessment Report (by IPCC on climate change)


xiv

Acronyms and abbreviations

FEAT
FEV
FGD
FID
FTIR
FTP
GC
GCM
GCTE
GHG
GVW
GWP
HAP
Hb
HCB
HCFC
HDV
HEPA
HFC
HGV
HMIP
HPLC
HVAC
IARC
ICAO
ICP
IDI
IGAC

INDOEX
IPC
IPCC
IPPC
IR
ISO
LA
LAI
LAPC
LAQM
LCA
LCPD
LDV
LEV
LGV
LIDAR
LNG

Fuel Efficiency Automobile Test – an optical gas sensor that scans across
the road width
forced expiratory volume – a measure of lung response to air pollutants
flue gas desulphurisation – a range of chemical process plant that
strips sulphur dioxide from flue gases before they are released to the
atmosphere
flame ionisation detector
Fourier transform infrared
Federal Test Program (US)
gas chromatography
General Circulation Model
Global Change and Terrestrial Ecosystems project

greenhouse gas
gross vehicle weight
global warming potential
hazardous air pollutants (US)
haemoglobin
hexachloro benzene – a pesticide
hydrochlorofluorocarbon – substitute for CFCs
heavy duty vehicle – such as a truck
high efficiency particulate air
hydrofluorocarbon – substitute for CFCs
heavy goods vehicle
Her Majesty’s Inspectorate of Pollution (UK)
high pressure liquid chromatography
heating, ventilating and air conditioning
International Agency for Research on Cancer
International Civil Aviation Organization
inductively coupled plasma
indirect injection
International Global Atmospheric Chemistry project
The Indian Ocean Experiment – an international study conducted to
assess the anthropogenic aerosols released from the Asian region
Integrated Pollution Control
Inter-Governmental Panel on Climate Change
Integrated Pollution Prevention and Control
infrared
International Organization for Standardization
local authority (UK)
Leaf Area Index
Local Air Pollution Control
Local Air Quality Management (UK)

Life Cycle Assessment
Large Combustion Plant Directive (EC)
light duty vehicle – such as a van
Low Emission Vehicle program (US)
light goods vehicle
light detection and ranging
liquefied natural gas


Acronyms and abbreviations

LRTAP
LTO
MACT
MATES
MDO
MFA
MMT
MEET
MOUDI
MRGR
MSW
MTBE
MTS
NAA
NAAQS
NAEI
NADP
NAME
NAPAP

NAQS
NCLAN
NETCen
NF
NMHC
NMMAPS
NMVOC
NOTLINE
NRPB
OAF
OCD
ODP
ODS
OECD
OTC
PAH
PAMS
PAN
PAR
PBDE

xv

long-range transboundary air pollution
landing and take-off
Maximum Achievable Control Technology (US)
Multiple Air Toxics Exposure Study
marine diesel oil
material flow analysis
methylcyclopentadienyl manganese tricarbonyl – organometallic manganese compound added to maintain the combustion properties of petrol

Methodology for Calculating Transport Emissions and Energy
Consumption project
micro-orifice uniform deposit impactor
mean relative growth rate – a measure of plant or animal vitality
municipal solid waste
methyl tertiary butyl ether
mainstream tobacco smoke – drawn from the cigarette during puffing
neutron activation analysis
National Ambient Air Quality Standards (US)
National Atmospheric Emissions Inventory (UK)
National Atmospheric Deposition Program (US)
Nuclear Accident ModEl
National Acid Precipitation Assessment Program – the major coordinated
programme in the US to understand the processes of, and responses to,
acid rain
National Air Quality Strategy (UK)
National Crop Loss Assessment Network – the US experimental programme on plant responses to air pollutants
National Environmental Technology Centre
non-filtered – an OTC supplied with ambient air
non-methane hydrocarbons – a sub-category of VOCs, defined by
compounds containing H and C but excluding methane because of its
relatively high background concentration in the atmosphere
National Morbidity, Mortality and Air Pollution Study (US)
non-methane volatile organic carbon
University of Nottingham Line Source Dispersion Model
National Radiological Protection Board
optical amplification factor – used to describe the response of UV to
ozone changes
ozone column depth
ozone depletion potential

ozone depleting substances
Organisation for Economic Co-operation and Development
open-top chamber – field chamber for plant pollution exposure
polycyclic aromatic hydrocarbons – a family of carcinogenic chemicals,
including benzopyrenes
particle analysis by mass spectroscopy
peroxyacyl nitrate – an irritant gas formed by the same photochemical
processes as ozone
photosynthetically active radiation – in the waveband 400–700 nm
polybrominated diphenyl ether – one of the persistent organic pollutants


xvi

Acronyms and abbreviations

PBL
PCA
PCB
PCDF
PCDD
PCR
PEC
PEM
PIB
PIXE
PM
PM10
PM2.5
POP

ppb
ppm
ppt
PSC
PSI
PTFE
PVC
QALY
QA/QC
RAF
RAG
RCEP
Re
RH
RIOPA
RPK
RVP
SAGE
SALR
SAR
SBLINE
SBS

planetary boundary layer – the vertical region of the Earth’s atmosphere
from ground level up to about 1500 m within which the physical and
chemical interactions with the surface mainly occur
principal component analysis
polychlorinated biphenyls – carcinogenic pollutants released from PCB
handling and poor PCB incineration
polychlorinated dibenzofurans (known as furans for short) – a toxic pollutant produced in small quantities by incinerators

polychlorinated dibenzodioxins (known as dioxins for short) – as above
polymerase chain reaction
particulate elemental carbon
proton exchange membrane – used in the context of hydrogen fuel cells
polyisobutylene – a 2-stroke petrol additive to reduce smoke production
proton-induced X-ray emission
particulate matter
particulate matter having an aerodynamic diameter less than 10 µm
particulate matter having an aerodynamic diameter less than 2.5 µm
persistent organic pollutant
parts per billion, or parts per 109, by volume
parts per million, or parts per 106, by volume
parts per trillion, or parts per 1012, by volume
polar stratospheric cloud – ozone depletion reactions occur on the surfaces of cloud particles
Pollution Standards Index (US)
polytetrafluorethylene – an inert plastic used for sample pipes when reactive gases such as ozone are present
polyvinyl chloride
quality-adjusted life years – method for assessing benefits of air quality
improvements
quality assurance/quality control
reactivity adjustment factor – a measure of the ozone-forming potential
of different fuel mixtures
radiatively active gas
Royal Commission on Environmental Pollution (UK)
Reynolds number
relative humidity
Relationships of Indoor, Outdoor and Personal Air – US project on seasonal concentrations of air pollutants in homes
revenue passenger kilometres
Reid Vapour Pressure – used in the context of estimating the evaporative
losses of fuel

Stratospheric Aerosol and Gas Experiment
saturated adiabatic lapse rate – the rate of decrease of temperature with
height in the atmosphere applicable to a parcel of air that contains liquid
water (typical range 4–9.8 °C km–1)
Second Assessment Report (by IPCC on climate change)
University of Nottingham (Sutton Bonington campus) Vehicle Emission
and Dispersion Model
sick building syndrome


Acronyms and abbreviations

SCA
SCC
SCR
SED
SEM
SI
SIP
SMPS
SOA
SOF
SOI
SOS
SPM
SRES
SST
Stk
STP
STS

SUM60
SUV
SVP
TAR
TEA
TEF
TEAM
TEM
TEOM
TEQ
THC
TOE
TOMPS
TRL
TSP
TWC
UARS
UFORE
ULPA
ULSP
UNECE

xvii

specific collection area
squamous cell carcinoma
selective catalytic reduction – used in abatement of nitrogen oxides
standard erythemal dose (of UV radiation)
scanning electron microscopy
Système International – the internationally recognised system of physical

units based on the metre, kilogram, second and Coulomb
State Implementation Plan (US)
scanning mobility particle sizer
secondary organic aerosols
soluble organic fraction
Southern Oscillation Index
Southern Oxidants Study (US)
suspended particulate matter
Special Report on Emission Scenarios – referred to the IPCC predicted
scenarios for GHG emissions
supersonic transport
Stokes’ number
Standard temperature and pressure – 0 °C and 1 atmosphere
sidestream tobacco smoke – released from the cigarette between puffing
sum of hourly-mean ozone concentrations > 60 ppb
sport utility vehicle
saturated vapour pressure
Third Assessment Report (by IPCC on climate change)
triethanolamine – a strong absorbent for NO2
toxic equivalent factor
Total Exposure Assessment Methodology study
transmission electron microscopy
tapered element oscillating microbalance
toxic equivalent – a standardisation of the toxicity of TOMPS
total hydrocarbon
tonnes oil equivalent
toxic organic micro-pollutants – generic term that includes PCDD,
PCDF and other minority chemicals with recognised toxicity at low (ppt)
concentrations
Transport Research Laboratory (UK)

total suspended particulate – all the particles in the air, regardless of
diameter
three-way catalyst – converts the three harmful gases in petrol-engined
vehicle exhaust to carbon dioxide, nitrogen and water
Upper Atmosphere Research Satellite
Urban Forest Effects – a model, originally developed by the US
Department of Agriculture, to assess forest canopy pollution uptake
potential
ultra low penetration air
ultra low sulphur petrol
United Nations Economic Commission for Europe – a group of countries, larger than the EU and including the United States, that has a
wide-ranging remit to organise joint ventures in European affairs


xviii

Acronyms and abbreviations

UNEP
UNFCC
USEPA
UV
VEI
VOC

WHO
WID
WMO
WRI
WTP

XRF
ZEV

United Nations Environmental Programme
United Nations Framework Convention on Climate Change
see EPA
ultraviolet radiation, conventionally defined as occurring in the wavelength range below 400 nm. Subdivided into UVA, UVB and UVC
Volcanic Explosivity Index
volatile organic compound – molecules, mainly containing hydrogen and
carbon, that are released from sources such as motor fuels and solvents.
They are toxic in their own right and serve as precursors for ozone
formation
World Health Organization
Waste Incineration Directive
World Meteorological Organization
World Resources Institute
willingness to pay – method for assessing the benefits of air quality
improvements
X-ray fluorescence
zero emission vehicles – presumed to be electric, and required by law to
make up a certain proportion of the fleet in California


Preface

Air pollution has been with us since the first fire was lit, although different aspects have been
important at different times. While many of us would consider air pollution to be an issue that
the modern world has resolved to a greater extent, it still appears to have considerable influence on the global environment. In many countries with ambitious economic growth targets
the acceptable levels of air pollution have been transgressed, resulting in an urban skyline
characterised by smog and dust clouds. Recent pictures of Beijing’s skyline during the 2008

Summer Olympics bear the hallmarks of this degradation, and reinforce the imperative need to
assess and mitigate the underlying causes more effectively for long-term benefits to the resident
populations. According to the World Bank, in 2007 air pollution cost about 3.8% of China’s
gross domestic product, mainly from diseases and loss of lives. In several Indian cities with
population of over a million, air pollution levels exceed World Health Organization standards.
It has been estimated that in India alone about 500,000 premature deaths are caused each
year by indoor air pollution, mainly affecting mothers and their children under 5 years of age.
Serious respiratory disease-related problems have been identified for both indoor and outdoor
pollution in major cities of several countries.
There is now a growing body of literature linking air pollution with short- and long-term
effects on human health. On a small scale, point source releases of individual pollutants can
cause localised responses ranging from annoyance to physical injury. In urban areas, high concentrations of gases and particles from coal combustion and, in more recent decades, motor
vehicles have produced severe loss of air quality and significant health effects. On a regional
scale, tropospheric ozone formation and acid deposition have been the major threats. Finally,
emissions of carbon dioxide and other radiatively active gases, together with stratospheric
ozone depletion, represent planet-scale assaults on the quality of our atmospheric environment.
In the Western world, stringent environmental legislations have been able to overcome the
erstwhile ‘conventional’ air pollution problems of foul and sooty skylines reminiscent of the
industrial revolution. In addition, the recent fuel crisis and growing awareness of sustainable
development have also contributed to reduction in aerial emissions of noxious pollutants. It
may be said that the lesson has been learned by a relative few but in order to restore air quality
that we need for our very survival the extent of the crisis has to be appreciated and addressed
by the population at large.
This book is designed to cover the whole gamut of air pollution issues, in most cases from
a quantitative standpoint. The revised third edition has brought the information up to date
with changes in legislation and air pollution science. In Chapters 1 and 2, the major sources
of gaseous and particulate air pollution, together with an outline of possible control measures,
are described. Mobile sources, which have taken over from stationary emitters as the major
threat to local air quality, are specifically addressed in Chapter 3. Chapter 4 describes some
commonly used methods for measuring the most wide-spread air pollutants. The temporal

xx

Preface

and geographical variations of concentrations and deposition on a national and international
scale are outlined in Chapter 5. Once released, the effects of these pollutants depend critically
on their dilution during dispersion, a process which is covered along with the fundamentals of
meteorology and air dispersion modelling in Chapter 6. Chapter 7 gives an extended example
of the data processing techniques that can be used to extract different types of information
from a set of air pollution measurements. Although people tend to associate air quality, or
the lack of it, with the outdoors, most of us spend up to 90% of our lives indoors, and specific aspects of this specialised environment are highlighted in Chapter 8. The new Chapter 9
extends the coverage of the previous editions by including information on air pollution mitigation approaches, specifically the role of vegetative interventions. The effects of air pollution on
plants, animals, materials and visual range are described in Chapters 10 and 11, and the recent
issues of climate change and ozone depletion in Chapters 12 and 13. The effects of pollutants
on the environment have led to a wide variety of standards and legislations for their control,
and these are reviewed in Chapter 14.
In the previous two editions, limitation to data access has resulted in a UK bias, followed in
order of emphasis by Europe, the US and the world at large. However, in the 3rd edition, air
pollution has been acknowledged as an international issue; additional efforts were expended in
balancing the amount of information provided for the developing world. Readers are encouraged to pursue other sources for greater depth of coverage on any particular issue. Some
suggestions are given as ‘Further Reading’ at the end of each chapter. These are not only useful
documents in their own right, but also contain references to many more specialist research
papers. Similarly, the figure captions cite many books, reports and research papers from which
Figures for this book have been taken. This book is aimed at a wide target audience, mainly
universities – both at undergraduate and at post-graduate levels with students from a wide
range of academic backgrounds. We hope it will be useful to our readers!
Abhishek Tiwary
Jeremy Colls

Chapter 1

Air pollutants
Sources and control of gases

Air pollution has remained a major problem in the modern society. However, in its conventional form of smoke and fumes, it dates back to the Middle Ages and is closely associated
with the Industrial Revolution and the use of coal. Pollution (in the general sense) was defined
in the Tenth Report of the Royal Commission on Environmental Pollution as:
The introduction by man into the environment of substances or energy liable to cause hazard to human health, harm to living resources and ecological systems, damage to structure
or amenity or interference with legitimate use of the environment.
This is a very broad definition, and includes many types of pollution that we shall not cover
in this book, yet it contains some important ideas. Note that by this definition, chemicals such
as sulphur dioxide from volcanoes or methane from the decay of natural vegetation are not
counted as pollution, but sulphur dioxide from coal-burning or methane from rice-growing
are pollution. Radon, a radioactive gas that is a significant natural hazard in some granitic
areas, is not regarded as pollution since it does not arise from people’s activities. The boundaries become more fuzzy when we are dealing with natural emissions that are influenced by
our actions – for example, there are completely natural biogenic emissions of terpenes from
forests, and our activities in changing the local patterns of land use have an indirect effect on
these emissions. The pollution discussed in this book is the solid, liquid or gaseous material
emitted into the air from stationary or mobile sources, moving subsequently through an aerial
path and perhaps being involved in chemical or physical transformations before eventually
being returned to the surface. The material has to interact with something before it can have
any environmental impacts. This interaction may be, for example, with other molecules in the
atmosphere (photochemical formation of ozone from hydrocarbons), with electromagnetic
radiation (by greenhouse gas molecules), with liquid water (the formation of acid rain from
sulphur dioxide), with vegetation (the direct effect of ozone), with mineral surfaces (soiling
of buildings by particles) or with animals (respiratory damage by acidified aerosol). Pollution
from our activities is called anthropogenic, while that from animals or plants is said to be biogenic. Originally, air pollution was taken to include only substances from which environmental

damage was anticipated because of their toxicity or their specific capacity to damage organisms
or structures; in the last two decades, the topic has been broadened to include substances such
as chlorofluorocarbons, ammonia or carbon dioxide that have more general environmental
impacts. Table 1.1 provides the most recently updated list of local and transboundary air
pollutants along with the details of the international and legislative directives that regulate
them in the UK. Most of these standards and the legislation are described in greater detail in
Chapter 14. This chapter exclusively deals with the gaseous components of the air pollutants
listed in the table; the particulate matter components are dealt with in Chapter 2.


2

Air pollutants: sources and control of gases

Table 1.1 Local and transboundary air pollutants along with their regulatory international and UK legislative
directives
Air pollutants

Directive

PM – PM 10, PM 2.5, NO x, O 3, SO 2, PAHs, Benzene,
1,3-butadiene, CO, Pb

Air Quality Strategy

SO 2, NH 3, NO x, NMVOC

NECD (National Emissions Ceilings Directive)

SO 2, NH 3, NO x, NMVOC, Heavy Metals, POPs

CLRTAP (Convention on Long Range
Transboundary Air Pollutants)

91 compounds including: CH 4, CO, CO 2 HFCs, N 2O, E-PRTR (European Pollutant Release and
SF 6, NH 3, NMVOC, NO x, PFCs, SO x, CFCs, As, Cd,
Transfer Register) which succeeds the EPER
Cr, Cu, Hg, Ni, Pb, Zn, PM 10, Benzene, HCl, HF, PAHs, (European Pollutant Emission Register)
PCBs, PCDD, PCDF, Gamma HCH, PCP, HCB
SO 2, NO x, CO, VOCs, metals, dust, asbestos,
chlorine and its compounds

IPPC (Integrated Pollution Prevention and
Control)

SO x, NO x, PM

LCPD (Large Combustion Plants Directive)

Dust (PM), HCl, HF, SO 2, NO x, Heavy metals, dioxins WID (Waste Incineration Directive)
and furans, CO
VOC

Solvent Emissions Directive

VOC

Paints Directive

SO 2

The Sulphur Contents of Liquid Fuels Directive

VOC

Petrol vapour recovery

SO 2, NO x, PM, lead, benzene, CO, ozone, PAH,
Cadmium, Arsenic, Nickel, Mercury

EU Air Quality Directives

1.1 UNITS FOR EXPRESSING POLLUTANT CONCENTRATION

Before we go any further, we must make a short detour to explain the units in which pollutant
concentrations are going to be discussed throughout this book. Two sets of concentration units
are in common use – volumetric and gravimetric.
If all the molecules of any one pollutant gas could be extracted from a given volume of the
air and held at their original temperature and pressure, a certain volume of the pure pollutant
would result. Volumetric units specify the mixing ratio between this pollutant volume and the
original air volume – this is equivalent to the ratio of the number of pollutant gas molecules to
the total number of air molecules. Owing to historical changes in the systems used for scientific units, there are at least three notations in common use for expressing this simple concept.
Originally, the concentration would be expressed, for example, as parts of gas per million
parts of air. This can be abbreviated to ppm, or ppmv if it is necessary to spell out that it is
a volume ratio and not a mass ratio. Later, to make the volumetric aspect more explicit and
to fit in with standard scientific notation for submultiples, the ratio was expressed as µl l–1.
Unfortunately, the litre is not a recognised unit within the Système International (SI). The SI
unit for amount of substance (meaning number of molecules, not weight) is the mol, so that
µmol mol–1 becomes the equivalent SI unit of volumetric concentration. This is correct but
clumsy, so ppm (together with ppb (parts per billion, 10–9) and ppt (parts per trillion, 10–12))

have been retained by many authors for convenience’s sake and will be used throughout this


Air pollutants: sources and control of gases

3

Table 1.2 Abbreviations for volumetric and gravimetric units
Volumetric

Gravimetric

Parts per million (micro)

10 –6

ppm

µl l –1

µmol mol –1

mg m –3

Parts per billion (nano)

10 –9

ppb

nl l –1

nmol mol –1

µg m –3

Parts per trillion (pico)

10 –12

ppt

pl l –1

pmol mol –1

ng m –3

book. Gravimetric units specify the mass of material per unit volume of air. The units are more
straightforward – µg m–3, for example. Unlike volumetric units, gravimetric units are appropriate for particles as well as for gases. These relationships are summarised in Table 1.2 for the
typical concentration ranges of ambient gaseous pollutants.
Both volumetric and gravimetric systems have their uses and their advocates. The volumetric
concentration is invariant with temperature and pressure, and therefore remains the same,
for example, while warm flue gas is cooling in transit through exhaust ductwork. When gas
enters a leaf, the effects may depend primarily on the number of molecular sites occupied by
the pollutant gas molecules – this is better indicated by the volumetric than by the gravimetric
concentration. However, if concentration is being determined by extracting the gas onto a
treated filter for subsequent chemical analysis, or health effects are being related to the mass
of pollutant inhaled, the result would normally be calculated as a gravimetric concentration.

1.1.1 Conversion between gravimetric and volumetric units
Since both gravimetric and volumetric systems are in use and useful, we need to be able to
convert between the two.
The basic facts to remember are that 1 mol of a pure gas (an Avogadro number of molecules, 6.02 × 1023) weighs M kg, where M is the relative molar mass, and takes up a volume
of 0.0224 m3 at standard temperature and pressure (STP – 0°C, 1 atmosphere).
For example, sulphur dioxide (SO2) has M = 32 × 10–3 + (2 × 16 × 10–3) = 64 × 10–3 kg, so
that pure SO2 has a density (= mass/volume) of 64 × 10–3/0.0224 = 2.86 kg m–3 at STP. But
pure SO2 is 106 ppm, by definition. Therefore:
106 ppm ≡ 2.86 kg m–3
1 ppm ≡ 2.86 × 10–6 kg m–3
= 2.86 mg m–3
and
1 ppb ≡ 2.86 µg m–3
Hence we can convert a volumetric concentration to its gravimetric equivalent at STP.

1.1.2 Correction for non-standard temperature and pressure
The temperature and pressure are unlikely to be standard, so we also need to be able to convert
gravimetric units at STP to other temperatures and pressures. At STP, we have 1 m3 containing


4

Air pollutants: sources and control of gases

a certain mass of material. When the temperature and pressure change, the volume of the gas
changes but it still contains the same mass of material. Hence we need only to find the new
volume from the Ideal Gas Equation:
PV
PV
1 1

= 2 2
T1
T2

(1.1)

where P1, V1 and T1 are the initial pressure, volume and absolute temperature and P2, V2 and
T2 are the final pressure, volume and absolute temperature.
In our case:
P1 = 1 atmosphere
V1 = 1 m3
T1 = 273 K
and we need to find V2.
Therefore, rearranging equation (1.1):
V2 =

T2 PV
T2
× 1 1=
273 P2
P2
T1

For example, the highest ambient temperature that we might find in practice is 50°C, and
the lowest ambient pressure at ground level might be 950 mbar. Hence:
T2 = 273 + 50 = 323K
and
P2 = 950/1013 = 0.938 atmosphere (because standard atmospheric pressure
= 1013 mbar)

Table 1.3 Conversion factors between volumetric and gravimetric units
Pollutant

Molecular weight M/g

To convert
ppb to µg m –3

µg m –3 to ppb

0°C

20°C

0°C

20°C

SO 2

64

2.86

2.66

0.35

0.38

NO 2

46

2.05

1.91

0.49

0.52

NO

30

1.34

1.25

0.75

0.80

O3

48

2.14

2.00

0.47

0.50

NH 3

17

0.76

0.71

1.32

1.43

CO

28

1.25

1.16

0.80

0.86