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ACKNOWLEDGEMENT
Development Team
Co-chairs: Yun-Chul Hong (Seoul National University, Republic of Korea) from 2017-2018; Jiming Hao(Tsinghua University, China); Frank Murray (Murdoch University, Australia); and Kalpana Balakrishnan(WHO Collaborating Center for Occupational and Environmental Health, Sri Ramachandra University, India)
from 2015-2016.
Authors:
Chapter 1: Why decisive action is needed to combat air pollution in Asia and the Pacific
Coordinating lead authors: Yun-Chul Hong (Seoul National University, Seoul, Republic of Korea) and KevinHicks (Stockholm Environment Institute, University of York, York, United Kingdom).
1.2 Air quality and health in Asia and the PacificLead authors: Kalpana Balakrishnan (World Health Organization Collaborating Center for Occupational
and Environmental Health, Sri Ramachandra University, Chennai, India); and Ajay Pillarisetti (University ofCalifornia Berkeley School of Public Health, Berkeley, California, United States of America).
Contributing authors: Ken Yamashita (Asia Center for Air Pollution Research, Niigata-shi, Japan) and Khalid
Yusoff (UCSI University, Kuala Lumpur, Malaysia).
1.3 Air quality and climate
Lead authors: Arnico Panday (International Centre for Integrated Mountain Development, Palan, Nepal);
Maheswar Rupakheti (Institute for Advanced Sustainability Studies, Potsdam, Germany); Kathleen Mar(Institute for Advanced Sustainability Studies, Potsdam, Germany); and Katsumasa Tanaka (National Institutefor Environmental Studies, Tsukuba, Japan).
Contributing authors: Chaman Gul (International Centre for Integrated Mountain Development, Palan, Nepal)
and Toshihiko Takemura (Kyushu University, Fukuoka, Japan).
1.4 Air quality, agriculture and ecosystems
Lead authors: Nguyen Thi Kim Oanh (Asian Institute of Technology, Pathum Thani, Thailand); Sase Hiroyuki(Asia Center for Air Pollution Research, Niigata-shi, Japan); and Kevin Hicks (Stockholm Environment
Institute, University of York, York, United Kingdom).
Contributing authors: Madhoolika Agrawal (Benares Hindu University, Varanasi, India); Allison Steiner(University of Michigan Energy Institute, Ann Arbor, United States of America); Lisa Emberson (Stockholm
Environment Institute, University of York, York, United Kingdom); Didin Agustian Permadi (Asian Institute ofTechnology, Pathum Thani, Thailand); Duan Lei (Tsinghua University, Beijing, China); and Feng Zhaozhong(Chinese Academy of Science, Beijing, China).
1.5 Socio-economic development pathways, air quality and Sustainable Development Goals in the Asiaand the PacificLead authors: Yeora Chae (Korea Environment Institute, Sejong, Republic of Korea); Young Sunwoo (Konkuk
University, Seoul, Republic of Korea); and Dang Espita (Clean Air Asia, Pasig City, Philippines).
Contributing authors: Gregory Carmichael (University of Iowa, Iowa City, United States of America); Hocheol
Jeon (Korea Environment Institute, Sejong, Republic of Korea); Miak Aw Hui Min (Ministry of Environment
and Water Resources, Singapore); and Everlyn Tamayo (Clean Air Asia, Pasig City, Philippines).

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONSiACKNOWLEDGEMENT
Chapter 2: Scenarios and Solutions
Coordinating lead authors: Markus Amann (International Institute for Applied Systems Analysis, Laxenburg,
Austria) and Hao Jiming (Tsinghua University, Beijing, China).
Contributing authors: Jens Borken-Kleefeld, Janusz Cofala, Adriana Gomez-Sanabria, Chris Heyes,
Lena Höglund-Isaksson, Gregor Kiesewetter, Zbigniew Klimont, Binh Nguyen, Pallav Purohit, Peter Rafaj,
Robert Sander, Fabian Wagner, Wolfgang Schöpp (all International Institute for Applied Systems Analysis,
Laxenburg, Austria); Chris Malley, Johan Kuylenstierna (both Stockholm Environment Institute, University
of York, York, United Kingdom); Wang Shuxiao and Ye Wu (both Tsinghua University, Beijing, China);
Drew Shindell and Karl Seltzer (both Duke University, Durham, United States of America); and Nathan
Borgford-Parnell (Climate and Clean Air Coalition, Paris, France).
Chapter 3: Closing the Implementation Gap: Bringing Clean Air to the Region
Coordinating lead authors: Eric Zusman (Institute for Global Environmental Strategies, Kanagawa, Japan);Frank Murray (Murdoch University, Perth, Australia); Ibrahim Rehman and Sumit Sharma (both The Energy
Resources Institute, New Delhi, India); and Kaye Patdu (UN Environment, Bangkok, Thailand).
Lead authors: Hu Tao (World Wide Fund for Nature and Beijing Normal University, Beijing, China); Kathleen
Mar (Institute for Advanced Sustainability Studies, Potsdam, Germany); Wanxin Li (City University
Hong Kong); Dang Espita, Kathleen Dematera and Alan Silayan (all Clean Air Asia, Pasig City, Philippines);Nathan Borgford Parnell (Institute for Governance and Sustainable Development, Washington, D.C.,
United States of America); Nguyen Thi Kim Oanh and Didin Permadi Augustian (both Asian Institute ofTechnology, Pathumthani, Thailand; and Bulganmurun Tsevegjav (Global Green Growth Institute, Seoul,
Republic of Korea).
Contributing authors: Susan Annenberg (George Washington University, Washington, D.C., United Statesof America); Eri Saikawa (Emory University, Atlanta, United States of America); Ray Minjares (International
Council on Clean Transportation, Washington, D.C., United States of America); Bert Fabian (UN Environment,
Nairobi, Kenya); Matthew Hengesbaugh, Premakumara Jagath Dickella Gamaralalage, Ran Yagasa, Yasuhiko
Hotta, Chen Liu, So-Young Lee, Xinling Feng, Kazunobu Onogawa, Yoshiaki Totoki, Mark Elder, Xianbing
Liu, Ngoc-Bao Pham and Kaoru Akahoshi (all Institute for Global Environmental Strategies, Kanagawa,Japan); Bidya Banmali Pradhan (International Centre for Integrated Mountain Development, Patan, Nepal);Suyesh Prajapati (MinErgy, Patan, Nepal); Mahendra Chitrakar and Shyam Maharjan (both Federation of
Nepalese Brick Industry, Kathmandu, Nepal; Mohammad Arif (Sharda University, New Delhi, India), Seema
Patel and Stevie Valdez (both Global Alliance for Clean Cookstoves, Washington, D.C., United States ofAmerica); Rajendra Shende (TERRE Policy Centre, Pune, India); Mao Xianqiang and Xing Youkai (both Beijing
Normal University, Beijing, China; Fu Lu and Wei Wan (both Clean Air Asia, Pasig City, Philippines); Takuro
Kobashi (Renewable Energy Institute, Tokyo, Japan); Kessinee Unapumnuk (Pollution Control Department,
Ministry of Natural Resources and Environment, Bangkok, Thailand); Yulia Yamineva (University of Eastern
Finland, Joensuu, Finland); Charlotte Unger (Institute for Advanced Sustainability Studies, Potsdam,
Germany); Pam Pearson and Alex Gittelson (both International Cryosphere Climate Initiative, Paulet,
USA; Markus Amann and Zbigniew Klimont (both International Institute for Applied Systems Analysis,
Laxenburg, Austria); and J.S. Kamyotra (Former Secretary, Central Pollution Control Board, Delhi, India).
Technical reviewers: Banalata Sen (Public Health Foundation of India); Eri Saikawa (Emory University); Neal
Fann (U.S. Environmental Protection Agency); Ho Kim (Seoul National University) Cunrui Huang (Sun Yat-sen
University); Iyngararasan Mylvakanam (UN Environment- International Environmental Technology Centre); Jianxinii

ACKNOWLEDGEMENT
Hu (Peking University); Jatinder Singh Kamyotra (Central Pollution Control Board of India); Khan Shahidul Huque(Department of Livestock Services of Bangladesh); Kok Sothea (Royal University of Phnom Penh);Peter Louie (Hong Kong Environmental Protection Department); Susan Anenberg (George Washington
University); Takashi Yorifuji (Okayama University); Toshihiko Takemura (Kyushu University); Umesh Chandra
Kulshrestha (Jawaharlal Nehru University); Young-Ran Hur, Shaofeng Hu, Jinhua Zhang, Kakuko Nagatani
Yoshida (UN Environment Asia Pacific office); Bin Jalaludin (University of New South Wales); Rajasekhar
Balasubramanian (National University of Singapore); Volodymyr Demkine (Independent Consultant);
Eui-Chan Jeon (Sejong University); Michael Brauer (University of British Columbia Canada); Yasushi Honda(University of Tsukuba); Hiroshi Hara (Tokyo University of Agriculture and Technology); Junjie Zhang (DukeKunshan University China); Edward Jonathan Roroia Danitofea (Ministry of Environment Climate change
Disaster Management and Meteorology of Solomon Islands) Yuji Masutomi (Ibaraki University); Haidong Kan(Fudan University); Shiqiu Zhang (Peking University); Anura Dissanayake (Ministry of Mahaweli Development
and Environment of Sri Lanka); Ghulam Malikyar (National Environmental Protection Agency of the Islamic
Republic of Afghanistan); Wongpun Limpaseni (Navamindradhiraj University); Supat Wangwongwatana(Thammasat University); team of Pollution Control Department of Thailand; team of UN Environment China
Office; team of Ministry of Ecology and Environment of China; Batbayar Jadamba (National Agency for
Meteorology and Environmental Monitoring of Mongolia; Faizal Parish (Global Environment Centre); Muhammad
Irfan Tariq (Ministry of Climate Change of Pakistan); Nguy Thi Khanh (Green Innovation and Development
Centre); Wei Peng (Harvard University); Eny Haryati (Directorate of Forest and Land Fire Management ofIndonesia); Shankar Prasad Paudel (National Pollution Control Strategy and Action Plan of Nepal); Wesam
Al Madhoun (Universiti Teknologi Petronas of Malaysia); Hazri Hassan (Ministry of the Environment andWater Resources of Singapore); Nyamjav Erdenesaikhan (Swiss Cooperation Office of The Embassy of
Switzerland in Mongolia); Alexander Baklanov (World Meteorological Organization); Alex Heikens (United
Nations Children’s Fund in Mongolia); Puput Ahmad Safrudin (KPBB of Indonesia); Vijay Shekhar Sharma(Paytm); Nguyen Van Dan (Horiba-Vietnam); Veerachai Tanpipat (Hydro and Agro Informatics Institute) andWorld Health Organization (WHO) team.
Editors: Bart Ullstein and Helen de Mattos.
Graphic design and lay-out: Rywin Nitiprapathananun.
Special thanks are extended to: Kaye Patdu and Suwimol Wattanawiroon (Asia Pacific Clean Air Partnership);Nathan Borgford Parnell and Helena Molin Valdes (Climate and Clean Air Coalition); Xiaoqian Zhou, Mayan
Mojado, Isabelle Louis, Dechen Tsering (UN Environment Asia Pacific Office); Iyngararasan Mylvakanamand Kaveh Zahedi (from 2015–2016).

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

iii

CONTENTS
Acknowledgement
List of boxesvii

List of figuresvii

List of tables

x

Forewordxi

Message from Co-Chairsxii

Key messages

1

Introduction

7

Chapter 1: Why decisive action is needed to combat air pollution in Asia and the Pacific13

1.1 Introduction

14

1.2 Air quality and health in Asia and the Pacific14			 1.2.1 Introduction

14

			 1.2.2 Estimates of population exposure to air pollution15

			 1.2.3 Trends in exposure to ambient and indoor air pollution

16

				

1.2.3.1 Exposure to ambient air pollution

16

				

1.2.3.2 Exposure to indoor air pollution16

			 1.2.4 Estimating the health burden attributable to air pollution

18

				

1.2.4.1 Health impacts

18

				

1.2.4.2 Regional studies on the health effects of air pollution21

			 1.2.5 State of knowledge and uncertainty

23

			 1.2.6 Conclusions

24

1.3 Air quality and climate25

			 1.3.1 Introduction25

			 1.3.2 Global climate impacts of air pollutants

25

				

1.3.2.1 Radiative and temperature impacts of different pollutants

26

				

1.3.2.2 Effects on precipitation

29

				

1.3.2.3 Effects on other aspects of climate29			 1.3.3 Impacts on the Asian cryosphere29		

1.3.4 Precipitation and the Asian monsoon

30

		

1.3.5 Impacts of climate change on air quality32		

1.3.6 The significance of short-lived climate pollutant strategies32		

1.3.7 Conclusions

34

1.4 Air quality, agriculture and ecosystems

iv

i

35

CONTENTS
		

1.4.1 Introduction35

			 1.4.2 Ozone impacts on important crops and ecosystems

36

			

1.4.2.1 Evidence of ozone impacts on crops and ecosystems

36

				

1.4.2.2 Factors affecting the extent of ozone impacts

40

			 1.4.3 Acidification and eutrophication effects of air pollution at local and regional scales41

			 1.4.4 Impacts of particulate matter on plants and ecosystems

43

				

1.4.4.1 Effects of particulate matter on radiation

43

				

1.4.4.2 ossible effects of particulate deposition to plants

44

			 1.4.5 Impacts of air pollution on the carbon cycle

44			 1.4.6 Conclusions45

1.5 Socio-economic development pathways, air quality and Sustainable Development

46

			 Goals in the Asia and the Pacific			 1.5.1. Socio-economic development pathways and air quality in Asia and the Pacific46			 1.5.2 Air quality and sustainable cities

49

				

1.5.2.1 Urbanization as a key driver of air pollution and greenhouse gas emissions

51

				

1.5.2.2 Air quality impacts on economies

52			 1.5.3. Air quality and the Sustainable Development Goals

55

			 1.5.4 Conclusions

56

Chapter 2: Scenarios and solutions

61

2.1 Introduction

62

2.2 Approach and methodology

63

			 2.2.1 Air quality management options with multiple benefits for development
2.3 Key findings6364			 2.3.1 Success in breaking the historic link between economic growth and pollution64			 2.3.2 Measuring atmospheric pollutants

67			 2.3.3 Energy policy and pollution control

67

			 2.3.4 The top 25 clean air measures for Asia71			 2.3.5 Health and other development benefits82			 2.3.6 Implementation costs90

			 2.3.7 Tailoring approaches to Asia’s diversity

91

2.4 Conclusions

97

Chapter 3: Closing the implementation gap: bringing clean air to the region
3.1 Introduction

101
102

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONSv

CONTENTS
3.2 Conventional emission controls

105

3.3 Next-stage measures

109

		

3.3.1 Agricultural residues

109

		

3.3.2 Prevention of peat and forest fires

110

		

3.3.3 Manure management

110

		

3.3.4 More efficient fertilizer application

111

		

3.3.5 Brick kilns

112

		

3.3.6 Shipping emissions

112

		

3.3.7 Solvents in industries and refineries

113

3.4 Development priority measures		

3.4.1 Clean cooking, heating and lighting

114

		

3.4.2 Clean energy

117

		

3.4.3 Energy efficiency standards – households and industry

117

		

3.4.4 Improved public transport

118

		

3.4.5 Electric vehicles

118

		

3.4.6 Solid waste management

119

		

3.4.7 Rice paddies

119

		

3.4.8 Wastewater treatment

121

		

3.4.9 Oil and gas

122

		

3.4.10 Coal mining

123

		

3.4.11 Hydrofluorocarbons

124

		

3.4.12 Sub-regional priorities

124

		

3.4.13 Air pollution episodes

124

3.5 Governance and finance

vi

113

125

		

3.5.1 Government agencies

130

		

3.5.2 Civil society and the general public

130

		

3.5.3 Funding

131

		

3.5.4 International and regional agreements

133

3.6 Conclusions

133

Annexes		137

References		

167

Abbreviations		

207

Glossary		

211

LIST OF BOXES
Box 1.1:
Box 1.2:
Box 1.3:
Box 1.4:
Box 1.5:
Box 2.1:
Box 3.1:
Box 3.2:
Box 3.3:
Box 3.4:
Box 3.5:

Hydrofluorocarbons
Regional haze and dimming
Visibility and winter fog in South Asia
Effects of ground-level ozone on wheat and rice
Regional haze effects in Singapore
Modelling tools used in this analysis
Waste heat recovery in Ningguo, China
Taxation policies and hybrid vehicles in Ulaanbaatar
Tokyo Metropolitan Government diesel strategy
Limiting open burning in Thailand
Roadmap on ASEAN Cooperation towards Transboundary Haze Pollution Control with
Means of Implementation (2016–2020)
Brick kilns in Nepal
Controlling emissions of volatile organic compounds in the Beijing-Tianjin-Hebei region
Clean cooking and the Sustainable Development Goals
Cambodia’s Sustainable Green Fuel Enterprise
Energy – One Less Nuclear Power Plant
Waste management in the Pacific islands and Small Island Developing States
Energy-efficient refrigeration in Indonesia
Sustainable Development Goals 16 and 17 and air pollution
Tropical Landscapes Finance Facility – leveraging public finance to support green growth

26
31
33
39
54
65
106
107
108
110
111

Box A1.1.1: Method for satellite and chemical transport model-derived estimates of ambient
air pollution used in Global Burden of Disease calculations
Box A1.1.2: Method for model-derived estimates of household air pollution used in the Global Burdenof Disease calculations138

Box 3.6:
Box 3.7:
Box 3.8:
Box 3.9:
Box 3.10:
Box 3.11:
Box 3.12:
Box 3.13:
Box 3.14:

113
114
115
116
118
120
124
129
132

ANNEXES139

LIST OF FIGURES
Figure 1:
Figure 2:
Figure 3:
Figure 1.1:
Figure 1.2:
Figure 1.3:
Figure 1.4:
Figure 1.5:
Figure 1.6:
Figure 1.7:
Figure 1.8:
Figure 1.9:

Sources and composition of PM2.5
Sources of ground-level ozone
Modelled sub-regions of Asia
Comparison of annual average PM2.5 population-weighted concentrations in 2016
with WHO air quality guidelines
Trends in annual average population-weighted PM2.5 exposure in Asia and the Pacific,
1990–2015
Change in the percentage of households reliant on solid fuels for cooking in Asiaand the PacificAge-standardized deaths per 100,000 people associated with air pollution,by country, 2012
Mortality associated with air pollution in the Asia and Pacific region, by country, 2016
Comparison of PM10 results from US and European meta-analyses, multi-city studies
and Asian systematic reviews
Comparison of increases in mortality from ozone results from US and European
meta-analyses, multi-city studies, and the Asian systematic reviews
Comparison of cause-specific hazard-ratio estimates: in a study of Chinese menover the age of 40
Present magnitudes of the radiative forcing of air pollutants, climate forcers,
and other changes for the period 1750–2011

8
9
11
16
17
18
19
20
22
22
23
27

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

vii

Figure 1.10: Temperature response by component for total anthropogenic emissions for a 1-year pulse 28
Figure 1.11: Surface dimming due to aerosols for the 2001–2003 period
31
Figure 1.12: (a) Aerosol optical depth acquired with MODIS instrument onboard Terra Satellite33
and (b) MODIS image showing clouds and fog over the Indo-Gangetic Plain on
20 November 2017
Figure 1.13: Some typical O3 injuries: a) bronzing on leaves of rice (Oryza sativa); b) interveinal
37
chlorosis in leaves of maize (Zea mays); c) interveinal chlorosis in onion leaves(Allium cepa); d) interveinal chlorosis (white patches) and necrosis (brown patches)in leaves of peanut (Arachis hypogaea) along with smaller plant biomass; e) bronzing
on the leaf surface of soybean (Glycine max) and f) interveinal chlorosis in leavesof wheat (Triticum aestivum)
Figure 1.14: 2001ensemble-mean patterns of nitrogen wet and dry deposition of oxidized
42(e.g. nitrates and NOx) and reduced (e.g. ammonium and ammonia) forms andsulphur wet and dry deposition (e.g. sulphate and sulphur dioxide)
Figure 1.15: PM2.5 concentrations and GDP per person by country in Asia and the Pacific47
Figure 1.16: Pathways of PM2.5 concentration and economic development by country in Asia
47
and the PacificFigure 1.17: PM2.5 concentrations and the percentage of electricity generated from coal by country
48
in Asia and the PacificFigure 1.18: Pathways of PM2.5 concentration and the percentage of electricity generation from coal48
by country in Asia and the PacificFigure 1.19: Pathways of CO2 emissions and economic development by country in Asia and the Pacific 49
Figure 1.20: Pathways of PM2.5 concentration and CO2 intensity by country in Asia and the Pacific50
Figure 1.21: Urbanization in Asia and the Pacific, 1990–2020
50
Figure 1.22: Location and size of urban agglomerations, and countries’ urban population
51
Figure 1.23: Annual average PM2.5 and PM10 concentrations in Asian cities
53
Figure 1.24: Labour output lost due to air pollution, by region, 2013
53
Figure 1.25: Links between air quality and the Sustainable Development Goals
57
Figure 2.1: Modelled sub-regions of Asia
63
Figure 2.2: Conceptual approach for identifying effective air quality management measures
64
that also contribute to the climate and sustainable development agendas
Figure 2.3: The suite of models used for this analysis and the interactions between models
66
Figure 2.4: The evolution of GDP and the pollutants that contribute to PM2.5 formation in Asia,
66
1990–2015
Figure 2.5: Ambient levels of PM2.5 in Asia in 2015
68
Figure 2.6: Distribution of population exposure to ambient PM2.5 and indoor pollution in 2015,
69
Asia-wide and for the modelled sub-regions
Figure 2.7: The contributions of different policy interventions to the decoupling of economic growth 70
from emissions of PM2.5 and its precursors under current legislation up to 2030,
following the IEA WEO energy scenario, and scope for further emission controls
Figure 2.8: Ambient levels of PM2.5 in Asia in 2030 under current legislation
71
Figure 2.9: Distribution of population exposure to PM2.5, in 2015 and in 2030 under current legislation 72
Figure 2.10: Impacts of the emission control measures that are now widely applied in Asia on
75
population-weighted mean exposure to PM2.5 in 2030, ranked by total exposure reduction
Figure 2.11: Impacts of Asia-specific next-stage air quality measures on population-weighted
77
exposure to PM2.5 in 2030, ranked by total reduction
Figure 2.12: Impacts of development priority measures on population-weighted exposure to78
PM2.5 in 2030, ranked by total reduction
Figure 2.13: Contributions to reductions in population-weighted mean exposure to PM2.5,
812015 and 2030

viii

Figure 2.14: Impacts on population-weighted exposure to PM2.5 in 2030 of 25 clean air measures
81
for Asia, ranked by further potential
Figure 2.15: PM2.5 concentrations in Asia in 2030 after implementation of82
the top 25 clean air measures
Figure 2.16: Population exposure to PM2.5 in 2015 and in 2030 for the different policy scenarios
82
Figure 2.17: Impacts of the top 25 clean air measures on population exposure to PM2.5, emissions of 83
climate forcers, and other SDG benefits
Figure 2.18: Premature deaths from exposure to ambient PM2.5, estimated with different
84
parametrizations of the exposure-response functions
Figure 2.19: Premature deaths from exposure to indoor PM2.5 pollution, estimated with different
85
parametrizations of the exposure-response functions
Figure 2.20: Estimated number of premature deaths associated with exposure to O3 in 2015 and86
in 2030 under current legislation, and with the top 25 clean air measures, Asia-wide
and for the modelled sub-regions
Figure 2.21: Estimated O3-induced crop loss in 2015 and in 2030 under current legislation, and with87
the top 25 clean air measures for Asia, expressed as a percentage of total crop production
Figure 2.22: Estimated O3-induced crop loss in 2015 and in 2030 under current legislation and87
with the top 25 clean air measures, expressed as tonnes of crop loss for four staple
crops, Asia-wide and for the modelled sub-regions
Figure 2.23: Changes in global mean temperature in 2050 from the three portfolios of measures89
relative to the current legislation baseline projection
Figure 2.24: Impact of the different climate forcers on global mean temperature resulting from89
implementation of the top 25 clean air measures, compared to the current legislation
baseline, 2015–2050
Figure 2.25: Annual average temperature change under the top 25 measures relative to the current
90
legislation baseline for the years 2046–2054
Figure 2.26: Air pollution control costs for 2015 and for the different portfolios of measures in 2030
91
Figure 2.27: Air pollution control costs by sector, for 2015 and for the different portfolios
92
of measures in 2030
Figure 2.28: The evolution of GDP and of the precursors of PM2.5 in the four modelled
93
sub-regions of Asia, 1990–2015
Figure 2.29: Changes in population-weighted exposure to PM2.5 between 2015 and 2030,
94
by modelled sub-region: the benefits of implementing the top 25 clean air measuresand remaining exposure
Figure 2.30: Numbers of people exposed to different levels of PM2.5 in ambient and indoor air,94
by modelled sub-region
Figure 2.31: Impacts of measures taken in modelled East Asia on population exposure to95
PM2.5 within the sub-region, ranked by further potential
Figure 2.32: Impacts of measures taken in modelled South Asia on population exposure95
to PM2.5 within the sub-region, ranked by further potential
Figure 2.33: Impacts of measures taken in modelled Southeast Asia on population exposure96
to PM2.5 within the sub-region, ranked by further potential
Figure 2.34: Impacts of measures taken in the modelled high-income countries on population
96
exposure to PM2.5 within the sub-region, ranked by further potential
Figure 3.1:
Strengthening the scientific basis for air quality management over four stages
102
Figure 3.2:
Number of countries with different levels of ambient air quality standards for PM10
105
Figure 3.3:
Number of countries with different ambient air quality standards for fine PM2.5
105
Figure 3.4:
Trends in solar- and wind-powered electricity generation in Asia and the Pacific117
Figure 3.5:
Technologies with the greatest potential to reduce methane emissions in the oil
123
and gas industry

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

ix

ANNEXES
Figure A2.1:
Figure A2.2:
Figure A2.3:
Figure A2.4:

The model suite used for this analysis and the interactions between models
143
The flow of information in the cost-effectiveness analysis of the GAINS model
144
The multi-pollutant/multi-effect framework of the GAINS model
145
Comparison of GAINS model results with national monitoring data and satellite-based
149
datasets (Dey et al. 2012, for India), as well as data reported in the WHO database (2016)
Figure A2.5: Comparison of GAINS model results with data reported in the WHO database (2016)
150
Figure A2.6: Ambient levels of PM2.5 in Asia in 2015 as modelled by GAINS
151
Figure A2.7: Levels of PM2.5 in ambient air in 2015 (μg/m3)
151
Figure A2.8: Impact of the air pollution and Sustainable Development Goal attainment mitigation
162
scenario on warming, estimated using absolute global temperature potentials
Figure A2.9: Global mean surface temperature change due to the mitigation scenario relative
163
to the baseline scenario (ºC) between 2015 and 2054
Figure A2.10: Geographic pattern of annual average surface temperature response to164
implementation of the 25 clean air measures, averaged over the three ensemble
members for the 2046–2054 decade
LIST OF TABLES
Table A:
Table 1:
Table 1.1:
Table 1.2:
Table 1.3:
Table 1.4:
Table 2.1:
Table 2.2:
Table 2.3:
Table 2.4:
Table 2.5:
Table 2.6:
Table 2.7:
Table 2.8:
Table 3.1:
Table 3.2:
Table 3.3:

The top 25 clean air measures
World health organization air quality criteria for PM2.5
Yield reductions in major crops in Asia at elevated ozone concentrations
in experimental studies
Estimated yield losses using modelling studies
Cost-benefit analyses of air quality management studies
Total welfare costs of air pollution, central projection (2010 US$)National air quality standards and global guidelines for PM2.5
The top 25 clean air measures for Asia
Emission controls that are proven and widely applied in Asia
Next-stage air quality measures to reduce particulate and precursor emissions
Measures aimed at development priorities that reduce PM2.5 precursor emissions
Key measures contributing to ground-level ozone mitigation
Additional measures aimed at ground-level ozone with co-benefits forsustainable development
Measures with additional benefits
The top 25 clean air measures
Wastewater management solutions
Factors enabling the success of clean air measures in Asia and the Pacific

4
9
38
40
56
57
68
73
75
76
77
79
79
80
103
122
126

ANNEXES
Table A1.1.1: Effects of ozone on major crops and forest trees in Asia from the experimental studies(% yield reduction)
Table A2.1: Population-weighted O3 concentrations estimated from the GISS and
GEOS-Chem models
Table A2.2: Summary of parameters used to calculate crop impacts
Table A2.3: Measures and key features

x

141
154
156
157

FOREWORD
It is an unfortunate fact that breathing clean air, the most basic humanneed, has become a luxury in many parts of the world. And while wehave beaten many of the big killers of the past, air pollution is now
ranked as one of the most serious health threats on the planet, witharound a third of global air pollution deaths occurring in Asia and thePacific. The good news, however, is that the region is also home tonumerous and tested solutions that can help beat pollution, save lives
and protect our planet.
Air Pollution in Asia and the Pacific: Science-based Solutions identifies
25 clean air measures that can positively impact human health, crop
yields, climate change and socio-economic development, as well as contribute to achieving the
Sustainable Development Goals. Implementing these measures could help 1 billion people breathecleaner air by 2030 and reduce global warming by a third of a degree Celsius by 2050.
The top 25 measures not only represent wins for cities and countries looking to improve air quality,
but also provide next-generation business opportunities and boost economic growth. India’s
east-coast state of Maharashtra and its capital city of Mumbai, for example, are embracing electric
mobility, aiming to increase the number of electric vehicles in the state to 500,000, creating
thousands of jobs and positioning the state as a globally competitive manufacturing destinationfor electric vehicles and their components.
We have seen how cooperation can lead to positive impacts. In China, the city of Shenzhen, withsupport from the national government and local transport agencies, is the first to adopt a fully
electric solution for its public network of more than 16,000 buses. In Nepal, brick kilns destroyed
during the 2015 earthquake have been rebuilt to be safer, less polluting and more efficient throughcollaboration between kiln owners and technical experts. In Toyama, Japan, integrating transport
planning and waste management while promoting renewable energy and energy saving has made theair cleaner and the city more climate resilient.
This report underlines the importance of strong engagement with governments, the private sector
and civil society – and the importance of simple and clear communication with citizens to be able tofully-implement recommended solutions.
I hope the report will inspire strong action from the Asia and Pacific region in our efforts to beatair pollution.
						
														JOYCE MSUYA							Acting Executive Director						
United Nations Environment Programme								December 2018

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

xi

MESSAGE FROM CO-CHAIRSAir Pollution in Asia and the Pacific: Science-based Solutions aims to support efforts to reduce air
pollution in Asia and the Pacific by proposing cost-effective options suited to the countries of theregion.
Air quality in Asia and the Pacific – what is its status?
The impact of air pollution on human health constitutes a serious public health crisis across Asiaand the Pacific. About 4 billion people, around 92 per cent of the region’s population, are exposed tolevels of air pollution that pose a significant risk to their health: exposure to pollution levels in excessof the World Health Organization (WHO) Guideline for public health protection is associated withelevated risks of premature death and a wide range of illnesses. Reducing this health burden
requires further action in Asia and the Pacific to reduce emissions that lead to the formation of fineparticulate matter (PM2.5) and ground-level ozone, which undermine people’s health and well-being
as well as food production and the environment.
Fortunately, governments in Asia and the Pacific have already adopted and implemented policies
to reduce pollution levels. Without these, population-weighted exposure to harmful PM2.5 would be
expected to grow by more than 50 per cent by 2030, based on the region’s projected economic growthof 80 per cent over the same period. These policies deliver significant benefits for air quality andhealth, a considerable achievement. However, they are not enough. Further action is necessary if thepeople of Asia and the Pacific are to enjoy air quality that conforms to the WHO Guideline.
Air quality in Asia and the Pacific – what can be done?
Air Pollution in Asia and the Pacific: Science-based Solutions uses the highest quality data available
and state-of-the-art modelling to identify the most effective 25 measures to reduce air pollution. The
analysis, which takes the region’s considerable diversity into account, groups the selected measures
into three categories that are fully described within the report:i. conventional emission controls focusing on emissions that lead to the formation of fine		 particulate matter;ii. further (next-stage) air-quality measures for reducing emissions that lead to the formation
		of PM2.5 and are not yet major components of clean air policies in many parts of the region; andiii. measures contributing to development priority goals with benefits for air quality.
If the 25 identified measures are effectively implemented, 1 billion people in Asia could enjoy air
quality that conforms to the WHO Guideline by 2030, compared to only about 360 million in 2015.
The reductions in outdoor air pollution could reduce premature mortality by a third, and about
2 million premature deaths from indoor air pollution could be avoided each year.
These 25 measures would also provide benefits for food and water security, environmental
protection and the mitigation of climate change.

xii

MESSAGE FROM CO-CHAIRSAir Quality in Asia and the Pacific – how to achieve benefits?
Regional and national differences in priorities for action and ease of implementation require a
flexible approach to tackling air pollution, so this report provides a range of options for countries
to consider in the context of their national circumstances.
The region already has considerable experience with the implementation of measures to reduce
pollutant emissions, but there is a need to strengthen compliance with existing policies andimprove their alignment in order to enhance both their implementation and their effectiveness.
Improving compliance will require significantly greater institutional and human resource capacity
to manage pollution-related issues in a wide range of agencies. This report discusses how betteralignment of policies will require carefully designed inter-agency coordination mechanisms.
The focus of most air pollution prevention policies is on cities. However, as this report identifies,
regions around cities contribute significantly to poor air quality within cities due to the atmospherictransport of air pollutants. To manage urban air quality effectively, regional, national, urban andrural authorities with responsibility for activities resulting in emissions need to collaborate moreclosely. As PM2.5 and ground-level ozone are regional air pollutants, joint regional efforts andinstitutional mechanisms are also required to address them.
Many challenges arise from the findings of Air Pollution in Asia and the Pacific: Science-based
Solutions. For example, the successful implementation of some smaller-scale measures may
require forms of governance that facilitate coordination within and across stakeholder
organizations at various levels of decision making. Collaborative regional and international
initiatives also have an important role to play, as they can help provide the financial, technologicaland capacity-building support needed to carry through many of the proposed measures.
Despite these challenges, the benefits of implementing these 25 cost-effective measures to reduce
air pollution outweigh the expense many times over, and we hope that this report will contribute toeffective action.
The Co-Chairs of Air Pollution in Asia and the Pacific: Science-based Solutions

JIMING HAO		
Tsinghua University,		China		YUN-CHUL HONG
Seoul National University,
Republic of Korea		FRANK MURRAY
Murdoch University,
Australia		

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

xiii

KEY MESSAGESKEY MESSAGESTHE NEED
Only the few ...
Less than 8 per cent of the population of Asia andthe Pacific enjoyed healthy air – within the World
Health Organization (WHO) Guideline – in 2015.
That means that around 4 billion people, the other92 per cent of the population, spread unevenly
across the region and with the highest numbers
living in South and East Asia, are exposed to levelsof air pollution that pose significant risks to theirhealth. Improving the lives of such a vast numberof people requires action to reduce the emissions
that result in the formation of fine particulatematter (PM2.5) and ground-level ozone, both ofwhich damage human health and well-being, as
well as food production and the environment.

It may not get worse, but will it get better?
If current policies aimed at limiting emissions are
effectively introduced and enforced, air quality will
be no worse in 2030 than it was in 2015, despite
population growth, rapid urbanization and an
ever-increasing demand for goods and services. But
nor will it be any better. This suggests that current
policies are mitigating air pollution in valuable but
limited ways. The 80 per cent economic growthforecast by 2030 compared with 2015 could beachieved with no further increase in air pollution
while lifting tens of millions of people out of poverty.
However, this still leaves more than 4 billion
exposed to health-damaging levels of air pollution.
Further action is needed to move towards the
WHO Guideline and protect public health.

THE SOLUTIONS
The widespread effective implementation of
only 25 measures will dramatically improve
the situation
State-of-the-art modelling has been conducted
on several hundred potential ways to reduce air

2pollution. The most effective 25 measures wereselected as the best proven options, benefiting
human health and the environment with regard tofood security, air, water and soil quality, biodiversity
and climate, whilst helping achieve the Sustainable
Development Goals (SDGs).

THE BENEFITS
Improving healthBy implementing the top 25 clean air measures, 22
per cent of the region’s population, around 1 billion
people, could enjoy air quality within the WHO
Guideline by 2030, compared to less than 8 percent in 2015. The number of people exposed topollution above the highest WHO Interim Target
could fall by 80 per cent to 430 million. Furthermore,premature mortality from outdoor air pollution could
decline by about a third, and an additional 2 million
premature deaths a year from indoor air pollution
could be avoided.

Improving food security and protecting
the environment
Ground-level ozone is the most important air
pollutant responsible for reducing crop yields, andthus affects food supply. Implementing the top 25
clean air measures could reduce estimatedozone-induced crop losses considerably – by 45
per cent for maize, rice, soy and wheat combined.
And, as ground-level ozone affects productive
grasslands and forests in similar ways, adoptionof the package of measures would also benefit
the health of natural ecosystems. The measures
will also reduce nitrogen and sulphur deposition to
ecosystems and have benefits for water and soil
quality, as well as biodiversity.

Enhancing water security
Additional warming due to black carbon and dustin the atmosphere and their deposition on glaciersand snowfields in the Hindu Kush-Karakorum-

Himalayan-Tibetan area is strongly linked toaccelerated melting of glaciers and snowfields inthe region. A reduction in particulate emissions from
implementing the top 25 clean air measures willslow the melting of glaciers and snowfields, reduce
the risk of disasters related to glacier lake outburst
floods, and help mitigate water insecurity forbillions of people.

Mitigating climate change
Implementing the top 25 clean air measures will
benefit efforts to mitigate climate change. It could
reduce carbon dioxide emissions in 2030 by almost
20 per cent relative to baseline projections andpotentially decrease the expected warming by athird of a degree Celsius by 2050. This would be asignificant contribution to the Paris Agreement targetof keeping global temperature rise this century
well below 2ºC.

Contributing to the Sustainable Development
Goals
The top 25 clean air measures will aid countries intheir efforts to achieve the SDGs. Implementing themwill improve air quality and mitigate climate change,
directly contributing to the realization of SDG 3:
Good Health and Well-being, SDG 11: Sustainable
Cities and Communities, SDG 12: Responsible
Consumption and Production and SDG 13: Climate
Action. Measures applied individually or in groups
will also contribute directly or indirectly to theachievement of all the other 13 SDGs and theirlinked targets.

MAKING IT HAPPEN
Providing options for Asia and the Pacific
The top 25 clean air measures are not equally
appropriate across the whole region. While
the measures are a package, the diversity of
sub-regions and countries in the region will mean
tailoring the prioritization and implementation of
the measures to national realities.

Requiring a small share of the region’s future
growthacross the region is projected to cost US$
300–600 billion per year, only about one twentiethof the increase of US$ 12 trillion in annual grossdomestic product (GDP) that is projected by 2030.
In addition to delivering substantial benefits tohuman health, food production, environmental
protection and climate change mitigation, a basket
of co-benefits will accrue, including savings on
pollution control.

Financing the clean air measures
Several of the top 25 clean air measures are alignedwith national development priorities and could be
supported from domestic public finance. The
private sector and businesses are ready to invest
in cleaner technologies, provided a favourable
enabling environment is in place. Concessional or
low-interest loans can support governments andother stakeholders in implementing the measures,
while climate finance mechanisms are available
for measures that reduce air pollution and mitigate
greenhouse gas emissions. Multilateral and bilateralfunding institutions could align their air pollution
strategies to the top 25 clean air measures, withresearch institutes and networks helping build the
additional technical capacity needed to introduce
and effectively implement the measures.

Mobilizing partnerships for multiple benefits
Continued economic growth will remain critical,
but economic growth alone will not be enoughto lead to the successful adoption and effective
implementation of the top 25 clean air measures.
That will require concerted efforts and integrated
action from governments, businesses andcivil society. The introduction and successful
implementation of the measures will entail building
bridges between traditional decision-making
structures and breaking down barriers to effective
partnership. The careful choice and implementationof the 25 clean air measures could foster cooperation
between a variety of ministries, local authorities,
industries and civil society organizations. Multiple
partners working together can implement change
for the greater good and sustainable developmentof Asia and the Pacific.

Implementation of the top 25 clean air measures

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

3

TABLE A: THE TOP 25 CLEAN AIR MEASURES
Regional application of conventional measures
Post-combustion controls

Introduce state-of-the-art end-of-pipe measures to reduce
sulphur dioxide, nitrogen oxides and particulate emissionsat power stations and in large-scale industry

Industrial process emissions
standards

Introduce advanced emissions standards in industries, e.g.,iron and steel plants, cement factories, glass production,
chemical industry, etc.

Emissions standards for road vehicles

Strengthen all emissions standards; special focus on
regulation of light- and heavy-duty diesel vehicles

Vehicle inspection and maintenance

Enforce mandatory checks and repairs for vehicles

Dust control

Suppress construction and road dust; increase green areas

Next-stage air quality measures that are not yet major components of clean air policies in many
parts of Asia and the Pacific4

Agricultural crop residues

Manage agricultural residues, including strict enforcementof bans on open burning

Residential waste burning

Strictly enforce bans on open burning of household waste

Prevention of forest and peatland
fires

Prevent forest and peatland fires through improved forest,
land and water management and fire prevention strategies

Livestock manure management

Introduce covered storage and efficient application ofmanures; encourage anaerobic digestion

Nitrogen fertilizer application

Establish efficient application; for urea also use urease
inhibitors and/or substitute with, for example, ammonium
nitrateBrick kilns

Improve efficiency and introduce emissions standards

International shipping

Require low-sulphur fuels and control of particulate
emissions

Solvent use and refineries

Introduce low-solvent paints for industrial and do-it-yourself
applications; leak detection; incineration and recovery

TABLE A: THE TOP 25 CLEAN AIR MEASURES (contd.)
Measures contributing to development priority goals with benefits for air quality
Clean cooking and heating

Use clean fuels – electricity, natural gas, liquefied petroleumgas (LPG) in cities, and LPG and advanced biomass cooking
and heating stoves in rural areas; substitution of coal bybriquettes

Renewables for power generation

Use incentives to foster extended use of wind, solar andhydro power for electricity generation and phase out theleast efficient plants

Energy efficiency for households

Use incentives to improve the energy efficiency of household
appliances, buildings, lighting, heating and cooling;encourage rooftop solar installations

Energy efficiency standards forindustry

Introduce ambitious energy efficiency standards for industry

Electric vehicles

Promote the use of electric vehicles

Improved public transport

Encourage a shift from private passenger vehicles to public
transport

Solid waste management

Encourage centralized waste collection with source
separation and treatment, including gas utilization

Rice paddies

Encourage intermittent aeration of continuously flooded
paddiesWastewater treatment

Introduce well-managed two-stage treatment with biogas
recovery

Coal mining

Encourage pre-mining recovery of coal mine gas

Oil and gas production

Encourage recovery of associated petroleum gas; stoproutine flaring; improve leakage control

Hydrofluorocarbon(HFC) refrigerant replacement

Ensure full compliance with the Kigali Amendment

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

5

INTRODUCTIONINTRODUCTION
AIR POLLUTION IMPACTS ON HUMANHEALTHThe impact of air pollution on human heath
represents a serious public health crisis acrossAsia and the Pacific. Fewer than 8 per cent of theregion’s people are exposed to levels of air pollutionthat do not pose a significant risk to their healthaccording to the World Health Organization (WHO)Guideline. There is now sufficient evidence fromepidemiological studies in Asia and the Pacific that
exposures to PM2.5 and ground-level ozone are
the most health damaging and account for large
attributable health burdens.

Fine particulate matter
Fine particles are directly emitted during the
combustion of fossil fuels and biomass including
forest and peat fires, and from industrial processes;

Fires

these particles include fly ash, various metals, salts,
and carbonaceous species including black andorganic carbon (Figure 1). Particle emissions also
originate from natural sources such as soil dust
and sea salt. Another substantial fraction of fineparticles is formed in the atmosphere throughchemical reactions involving gaseous emissions.
Sulphur dioxide, nitrogen oxides and volatile organic
compounds from fuel combustion and industrial
processes, and ammonia from agricultural activities
are the main contributors to the formation of fineparticulates in this way. In this report, fine particulatematter is considered to be PM2.5 – particles with
an aerodynamic diameter equal to or less than 2.5
micrometres (μm). There is a variable relationshipwith PM10, particles with an aerodynamic diameter
equal to or less than 10 μm, that may depend on
the sources as well as the physics and chemistryof the atmosphere.The relationship may vary withlocation, season and weather conditions.

SO2

Industry

VOCs

Transport
includingshipping

Atmosphericchemistry

NOX

Indoorcooking/heating

Secondary
PM2.5

NH3

Dust

Agriculture:
fertilizers/livestock

Primary
PM2.5

SO2 – sulphur dioxide; VOCs – volatile organic compounds; NOx – nitrogen oxides; NH3 – ammonia;
PM2.5 – particulate matter with an aerodynamic diameter equal to or less than 2.5 micrometres (μm)
Primary inorganic and organic PM2.5 particles are those released directly to the atmosphere and inhaled by the population; theseinclude dust from roads and black carbon from combustion sources. Secondary inorganic and organic PM2.5 particles, on the other
hand, are formed in the atmosphere from chemical reactions involving primary gaseous emissions: nitrogen oxides and sulphur dioxide
mainly from cities and industrial areas; ammonia mainly from agricultural sources; and volatile organic compounds from solvent use.
Because of their small size, both primary and secondary particles can be transported over large distances.

FIGURE 1: SOURCES AND COMPOSITION OF PM2.5

8Stratospheric
O3

Stratosphere~10-50 km.
Troposphere~0-10 km.
Fires

NMVOCsO3

Industry
NOXTransport
includingshippingIndoorcooking/heating

CO

Agriculture:
fertilizers/livestock

CH4

Chemical
destruction

Deposition
Crops

PeopleVegetation

NMVOCs – Non-methane volatile organic compounds; NOx – nitrogen oxides; CO – carbon monoxide; CH4 – methane; O3 – ozone

FIGURE 2: SOURCES OF GROUND-LEVEL OZONEGround-level ozone
Ground-level ozone causes serious damage tohuman health and vegetation. It is formed in theatmosphere by reactions between carbon
monoxide, nitrogen oxides, and volatile organic
compounds, including methane, in the presenceof sunlight (Figure 2). The substances that
contribute to the formation of ozone are emitted
from a wide range of sources including vehicles,industrial production, fuel combustion, naturalemissions from vegetation and soils, vegetation
fires including wildfires, controlled burns andagricultural burning, and solvents, as well as
emissions from waste disposal. Nitrogen oxides

reduce ozone close to their emission sources,usually within urban areas, but enhance its formation
downwind. Emissions of volatile organic compounds
are potent contributors to ozone formation at theurban scale, and ozone has a lifetime in theatmosphere of the order of several weeks, sufficiently
long for it to be transported over longer distances.

World Health Organization guidelines
The WHO has established air quality guidelines toprotect human health, with a value for PM2.5 of 10
micrograms per cubic metre (μg/m3) as an annual
mean concentration in ambient air (Table 1).

TABLE 1: WORLD HEALTH ORGANIZATION AIR QUALITY CRITERIA FOR PM2.5
Annual mean PM2.5
concentration

WHO
Air Quality Criteria

35 µg/m3

WHO Interim Target 1

25 µg/m3

WHO Interim Target 2

15 µg/m3

WHO Interim Target 3

10 µg/m3

WHO Guideline

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

9While based on scientific evidence of health impacts,
this level may seem aspirational, and even out ofpractical reach for some countries given their current
positions. As a result, the WHO has establishedInterim Targets as milestones along the way towards
an end-goal of achieving the WHO Guideline value.

Looking forward
Fortunately, governments in the Asia and Pacificregion have successfully adopted and implemented
policies that have reduced pollution levels andwill continue to do so in future. Without them,
population-weighted exposure to harmful
particulate matter would have been expected to
grow by more than 50 per cent by 2030, basedon the region’s projected 80 per cent economic
growth. Although current policies deliver clear andsignificant improvements in air quality and provide
health benefits, a considerable achievement,
further action is needed to achieve the WHO
Guideline and protect public health.

Air Pollution in Asia and the Pacific:
Science-based Solutions
Air Pollution in Asia and the Pacific: Science-based
Solutions, the first comprehensive, solution-oriented,
interdisciplinary scientific assessment of the air
pollution outlook and policy measures in Asia andthe Pacific, and this summary, have been preparedin response to Resolution 1/7 of the First Sessionof the United Nations Environment Assembly in
2014, which called for UNEP to prepare regional
reports on air quality issues.
This report is the product of close collaboration
between the Asia Pacific Clean Air Partnership(APCAP) and the Climate and Clean Air Coalition(CCAC). The assessment process was chaired bythree Co-Chairs from the Asia and Pacific region:
Professor Jiming Hao, Tsinghua University, China;
Professor Yun-Chul Hong, Seoul National University,
Republic of Korea; and Professor Frank Murray,
Murdoch University, Australia, and was coordinatedby: APCAP; CCAC Secretariat; Institute for Global
Environmental Strategies (IGES); Stockholm
Environment Institute (SEI); UN Environment, Asiaand the Pacific Office; and International Institutefor Applied Systems Analysis (IIASA).

10

Aims
The report and its summary aim to support efforts
to address air pollution in Asia and the Pacific byproviding options for tackling air pollution in thecontext of the SDGs. To this end, it brings together
evidence of historical trends with future development
perspectives and provides detailed analysesof past and future economic trends and theirimplications for ambient and indoor air pollution.
From there, the report identifies a detailed portfolioof 25 cost-effective measures for technologicaland policy interventions that would contributeto the achievement of the SDGs while delivering
the greatest benefits for human health, crop
yields, climate and the environment, as well associo-economic development.
The report provides a clear picture of the benefits
to be gained by adopting the measures and offerssome implementation guidance through real-lifecase studies. It is also hoped that the report will act
as a platform to share experiences with practicalactions to prevent and control atmospheric pollution
across the Asia and Pacific region.

Structure
Chapter 1 assesses from a regional perspective themany impacts that poor air quality can have, not only
on human health, but on the environment, climate
and development priorities.
Chapter 2 identifies the priority measures that mosteffectively reduce health impacts across the region
and help to meet other development goals. This
includes the benefits of taking action on air pollution
for mitigating climate change.
Chapter 3 explains how these measures can be
implemented and provides examples of where
they have been successfully applied in the region.
It also identifies enabling environments and factors
supporting their implementation at scale acrossthe region.

As a result, the sub-regions used in the report arecomposed as follows:

Target audience
The main report, Air Pollution in Asia and the Pacific:
Science-based Solutions, is intended to be used byprofessionals and practitioners to inform policy anddecision makers working in the areas of air pollution
and climate change to develop national policies andstrategies to address air pollution using proven,cost-effective, readily implementable measures.

Asia and the PacificIn the report, results are presented as aggregatesfor four Asia and the Pacific sub-regions (Figure 3).
While based on the sub-region components practicallydefined by the UN Environment Asia and thePacific Office and the World Bank, countries werere-grouped for the purposes of modelling to takeaccount of the availability of data and ensure thescientific consistency of the modelling results. These
sub-regions are used for scientific convenienceand have no official or administrative significance.
The modelling studies were conducted using
available data on emissions and ambientconcentrations of the relevant pollutants in Asia,
but such data were obtainable for only a few
countries in the Pacific area. The absence of dataof a suitable quality for large parts of the Pacificprevented modelling to the necessary level ofreliability in the Pacific.

East Asia
High-income countries

		East Asia (modelled East Asia) includes China,
		 Democratic People’s Republic of Korea andMongolia (and excludes Japan and Republic ofKorea);
		
		
		
		
		

Southeast Asia (modelled Southeast Asia)
includes Cambodia, Indonesia, Lao People’s
Democratic Republic, Malaysia, Myanmar,
Philippines, Thailand and Viet Nam (and excludes
Brunei Darussalam and Singapore);		South Asia (modelled South Asia) includes
		 Afghanistan, Bangladesh, Bhutan, India, Iran,		 Maldives, Nepal, Pakistan and Sri Lanka; and		High-income countries (modelled high-income
		 countries) includes Brunei Darussalam, Japan,
		 Republic of Korea and Singapore.

BruneiSingapore

South Asia
Southeast Asia

FIGURE 3: MODELLED SUB-REGIONS OF ASIA

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

11

CHAPTER

1

Why decisive
action is needed tocombat air pollutionin Asia andthe Pacific1.1 INTRODUCTION
In this first chapter, current knowledge on air
pollution impacts in the Asia and Pacific region
are described and summarized in the context ofinternational developments. These are the essential
components that need to be taken into account for
a comprehensive assessment of the consequencesof air-polluting emissions and effective air quality
management in the region. These include the effectsof the major air pollutants – fine particulate matter
equal to or less than 2.5 microns in aerodynamic
diameter (PM2.5) and ground-level ozone (O3) – on
human health (Section 1.2), the climate (Section 1.3),
agricultural production and ecosystems (Section
1.4) and socio-economic development pathways(Section 1.5), including links to the Sustainable
Development Goals (SDGs) in the countries of Asiaand the Pacific. The treatment of impacts, or thecountries in which they occur, is not exhaustive,
but the information presented has been selected
to underpin the analysis in Chapter 2 and theimplementation of measures to reduce air
pollution in the region in Chapter 3. Where relevant,an attempt has been made to include all thewell-documented impacts of air pollution in the
Asia and Pacific region and the major uncertainties,
synergies and trade-offs between these arehighlighted, as well as the multiple benefits
that are possible through targeted mitigation ofpolluting emissions.

1.2 AIR QUALITY AND HEALTH IN ASIA
AND THE PACIFIC
1.2.1 Introduction
Air pollution is well recognized as an importantrisk factor for global disease burdens and has amajor impact on human health (Landrigan et al.
2017; Thurston and Lippmann 2015; Lippmann2013; Loomis et al. 2013; Brauer et al. 2012),
particularly among the poor and vulnerable
such as the aged and children (Hajat et al. 2015).
According to recent estimates, each year 7 million
premature deaths worldwide and 215.5 million
disability-adjusted life years (DALYs) are attributable
to exposure to ambient and indoor air pollution,with the rapidly developing countries in Asiaand the Pacific bearing much of this burden

14(WHO 2018; GBD 2018a; Cohen et al. 2017; WHO
2016; GBD 2016; GBD 2015a). While ambient
air pollution is especially severe in some of thefastest-growing urban regions, the International
Energy Agency (IEA) estimated for 2015 thatapproximately 2.7 billion people globally1, of whom
1.9 billion live in Asia, continue to depend on burningsolid fuels such as wood, coal, charcoal, crop
residues and dung in their homes for cooking andheating (IEA 2016), resulting in very high levels ofindoor air pollution. Consequently, the health risk
posed by air pollution in the Asia and Pacific region
impacts urban and rural communities, with thetotal mortality burden from indoor and ambient air
pollution fourth behind dietary, tobacco and highblood pressure risks (GBD 2017a; GBD 2015a). In
2013, it was estimated that exposure to ambientand indoor air pollution cost the world’s economy
some US$ 5.11 trillion in welfare losses (WorldBank 2016). In terms of magnitude, in South andEast Asia and the Pacific this is equivalent to 7.4
and 7.5 per cent of those regions’ gross domestic
products (GDP) respectively (World Bank 2016).
Epidemiological studies conducted over the last
three decades have established robust associations
between long-term exposure to ambient and indoor
air pollution and premature mortality associatedwith, for example, ischemic heart disease, stroke,chronic respiratory diseases and lung cancer,
thereby substantially reducing life expectancy(Lippmann et al. 2013; Anderson et al. 2012; Pope etal. 2008). Morbidity from such conditions as chronic
respiratory symptoms, including bronchitis andasthma, and from cataracts – although less serious
when compared to mortality – also constitute someof the most deleterious effects of air pollution. In
addition, a growing body of literature points to thespecial vulnerability of children to air pollution, withpremature deaths from pneumonia. Additional
effects on children’s rapidly developing respiratory,
neurological and immune systems are thought topersist well into adulthood (UNICEF 2016).

1

Estimates and definitions of global solid fuel use vary. For 2015, IEA
estimated 2.5 billion solid fuel users; this estimate does not include coal,
which adds approximately 200 million additional households worldwide. The Health Effects Institute and Institute for Health Metrics and
Evaluation estimate 2.45 billion in 2015, including coal use (HEI 2018);
and the World Health Organization (WHO) estimates nearly 3 billion
in 2012 (WHO 2016), including coal use. IEA estimates are used formodelling in Chapter 2 and are reported here for consistency.

An expanding body of evidence points to both
short-term consequences of exposure to air
pollution (Luo et al. 2015; Shah et al. 2015) and anumber of areas of growing concern, including
fertility and birth-related outcomes (Malley et al.
2017; Frutos et al. 2015; Amegah et al. 2014;
Stieb et al. 2012; Shah and Balkhair 2011),
neurocognitive effects (Babadjouni et al. 2017;
Cacciottolo et al. 2017; Chen et al. 2017b; Perera
2017; Brockmeyer and D’Angiulli 2016; Casanova
et al. 2016; Clifford et al. 2016; Heusinkveld et al.
2016; Kioumourtzoglou et al. 2016; Levy 2015;
Perera et al. 2014) and diabetes (Cosselman et al.
2015; Eze et al. 2015; Meo et al. 2015; Thiering andHeinrich 2015; Krewski et al. 2009).
Drawing on currently available epidemiologicalstudies, particularly on chronic population exposure,PM2.5 has served as the most consistent and robust
predictor of mortality in studies of long-term
exposure to air pollution. Ground-level O3, a gas
produced through atmospheric reactions ofprecursor emissions in the presence of sunlight(Figure 2, Introduction), has also been associatedwith mortality and respiratory disease independentof exposure to PM2.5 (Atkinson et al. 2016).
A considerable number of epidemiological studies,mostly time series, on acute exposure to air
pollution ranging from days to weeks have been
carried out in the region, showing similar effects onpremature mortality as studies carried out in North
America and Europe. However, the health effects ofacute episodic events, such as forest fires or dust
storms, are yet to be described by solid scientificresearch in Asia and the Pacific.
This section provides a regional overview of:i. population exposure profiles and trends
for PM2.5 and O3 in relation to World HealthOrganization (WHO) air quality guidelines;
ii. estimates of attributable burden of disease
from the 2012 WHO and 2016 Institute for
Health Metrics and Evaluation (IHME) Global
Burden of Disease (GBD) assessments; andiii. estimates of risks from recent short-term timeseries and a few long-term cohort studies fromacross countries in Asia and the Pacific.

These sections give the context for the modelling
efforts described in Chapter 2 that estimate theexpected population PM2.5 exposure reductions
and associated health benefits of alternativeemission control strategies for air pollution
throughout the region. This section underlines thefact that there is now sufficient evidence for action
to reduce the impacts of air pollution on humanhealth in Asia and the Pacific.
1.2.2 Estimates of population exposure to
air pollution
The majority of epidemiologic research on exposure
to air pollutants is based on ambient air quality datafrom ground-based monitoring networks. Estimatesof ambient air quality concentrations from the WHO
database on air pollution currently are made up ofground-level measurements from 500 cities in the
Asia and Pacific region2. These indicate that theregion contains 17 of the 30 most polluted cities
in the world, although the extent and quality of air
pollution monitoring data informing this databasevary widely by city, country and sub-region.
Air pollution is not just a problem in cities. Nearly
2.7 billion people around the world, of whom more than
1 billion live in the Asia and Pacific region, primarily inrural communities, are exposed to extremely highconcentrations of PM2.5, carbon monoxide (CO)and a range of other air toxics, including volatileorganic compounds (VOCs), polycyclic aromatichydrocarbons (PAHs) and heavy metals, from theuse of solid fuels such as wood, charcoal, coal anddung in their homes for cooking and heating (IEA
2016; Bonjour et al. 2013). Unlike ambient air
pollution, where monitoring networks exist, dataon indoor air pollution exposure are only available
from a relatively limited number of research studies(Balakrishnan et al. 2011). Further complicating theissue are additional sources of air pollution, including
open burning of solid waste and refuse (Kodros et al.
2016) and global shipping (Liu et al. 2016), that may
contribute to ill-health.
To provide an overview of air pollution levels acrosscountries, particularly in the rapidly developing
urban areas of low- and middle-income countries,2

see: http://www.who.int/phe/health_topics/outdoorair/databases/en/

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

15

and the large rural and suburban areas that lackany air quality monitoring stations, researchers
apply a consistent methodology (Cohen et al.
2017) to estimate exposure to ambient and indoor
air pollution. Descriptions of the global ambientand indoor air pollution models are provided in
Annex 1.1.
1.2.3 Trends in exposure to ambient and indoor air
pollution
1.2.3.1 Exposure to ambient air pollution
The GBD study estimates that in 2016 thepopulation-weighted annual mean concentrationof PM2.5 in the Asia and Pacific region was 58
micrograms per cubic metre (μg/m 3), with amajority of the population living in areas exceeding
the WHO Interim Target 1 of 35 μg/m 3. The
population-weighted annual mean concentration
using population density is used in these studies
as it is more representative of the population
exposure to PM2.5 than monitoring data (Brauer
et al. 2016; van Donkelaar et al. 2016). Compared

to a global population-weighted annual mean
concentration of 51 µg/m3 and the 58 per cent of
the global population that lives in areas that exceed
WHO Interim Target 1, it is clear that the populationof Asia and the Pacific is among the most highly
exposed to PM2.5 in the world (Figure 1.1).
Long-term trends for PM2.5 and ozone
There was an estimated 19 per cent increase inannual population-weighted PM2.5 concentrationsin the Asia and Pacific region between 1990
and 2015, with many countries experiencing an
increase in population exposure (HEI 2018). The
rates of increase within the region exceeded the
10 per cent global increase during this same
period (Figure 1.2). Ozone concentrations werealso estimated to have increased at a greater rate
throughout South Asia than globally.
1.2.3.2 Exposure to indoor air pollution
Globally, average daily particulate matter
concentrations in homes burning solid fuels

PM2.5 (μg/m3)≤ 10 (<WHO Guildline)
10-15 (<WHO Target 3)15-25 (<WHO Target 2)20-35 (<WHO Target 1)>35 (>WHO Target 1)

FIGURE 1.1: COMPARISON OF ANNUAL AVERAGE PM2.5 POPULATION-WEIGHTED
CONCENTRATIONS IN 2016 WITH WHO AIR QUALITY GUIDELINES
Source: HEI 201816

Aggregate

55
50
45
40

60

30
Country-level

Population-weighted annual average PM2.5 (μg/m3)

90

ESCAP
World

Afghanistan

Myanmar

Australia

Nepal

Bangladesh

New Zealand

BhutanPakistan

Brunei

Papua New Guinea

Cambodia

Philippines

China

Republic of Korea

Democratic
Republic of Korea

Samoa

Federated Statesof Micronesia
Fiji
India
Indonesia
Iran
Japan
Laos

Singapore
Solomon Islands
Sri Lanka
Thailand
Timor-Leste
Tonga
Vanuatu
Viet Nam

Malaysia
Maldives
Marshall Islands
Mongolia

1990

2000

2010

Year

Note: The aggregate panel shows the global trend.

FIGURE 1.2: TRENDS IN ANNUAL AVERAGE POPULATION-WEIGHTED PM2.5
EXPOSURE TO AMBIENT AIR POLLUTION IN ASIA AND THE PACIFIC, 1990–2015
Source: Adapted from data available from State of Global Air 2018 (stateofglobalair.org)

have been reported to range between 300 and
3,000 μg/m3 (Clark et al. 2013; Balakrishnan
et al. 2011). The distribution of exposures isheterogeneous and complex, with multiple
determinants, such as the fuel/stove type, kitchenarea ventilation, quantity of fuel, age, gender andtime spent near the cooking area, influencing
spatial and temporal patterns of exposure within
and between households. Regardless of thevariability in results across studies and within andbetween countries, however, there is unequivocal
evidence of extreme exposure in all communities
that use solid cooking fuel, often many times
higher than the recommended WHO guidelines forambient and indoor air quality intended to protect
public health – the guidelines for daily mean PM2.5

and particulate matter equal to or less than 10 microns
in aerodynamic diameter (PM10) are 25 μg/m3 and50 μg/m3, respectively (WHO 2006).
While the proportion of households relying on solid
cooking fuels has decreased over the last few
decades (Figure 1.3), this has been offset in some
but not all countries by a simultaneous increasein population (Bonjour et al. 2013), resulting in
the number of people using solid cooking fuelsremaining nearly the same.

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

17

1.2.4 Estimating the health burden attributable toair pollution
The GBD study relies on the use of integrated
exposure-response (IER) functions to generateconsistent risk estimates across the four major
categories of combustion particle exposures –indoor air pollution, ambient air pollution, active
tobacco smoking, and second-hand tobaccosmoke (SHS). The IER functions have beenmodelled relating PM 2.5 exposure to specificdiseases – ischemic heart disease, stroke, lungcancer, adult chronic obstructive pulmonary
disease and child acute lower respiratory infections(Cohen et al. 2017; Burnett et al. 2014). The IER
functions are based on an exponential decay
model that does not constrain the relationshipbetween concentration and outcome to the linear.
Additionally, the modelling allows the evidence
from epidemiological studies concerning any of thecategories of combustion particles to be pooledusing the daily dose of PM2.5 as the primary exposure
metric (Annex 1.1).
1.2.4.1 Health impacts
Air pollution – indoor and ambient PM 2.5 air
pollution – is associated with 7 million premature
deaths each year globally (WHO 2018; GBD
2018a; GBD 2017a; WHO 2016; GBD 2015a).
In 2012, low- and middle-income countries in
the Western Pacific and Southeast Asia regions(as defined by WHO 2016) had the highest
age-standardized death rate per 100,000 people –65 and 59, respectively (Figure 1.4).
It is important to note that current methods ofcalculating the health impact of ambient air pollution
assume that windblown dust affects health thesame way as PM2.5 from other sources. The healthAggregate

50
40
100

Country-level

Solid fuel use (%)

75

50

25

World
Afghanistan

Mongolia

Australia

MyanmarBangladesh

Nepal

BhutanBrunei
Cambodia

New Zealand

China

Philippines

Democratic
Republic of Korea

Republic of Korea

Federated Statesof Micronesia

Singapore
Solomon Islands

India

Sri Lanka

Indonesia

ThailandIran

Timor-Leste

Laos
Malaysia

1990

2000

2010

Year

Samoa

Fiji

Japan

0

PakistanPapua New Guinea

Tonga
Vanuatu
Viet Nam

Maldives
Marshall Islands

Note: The aggregate panel shows the global trend.

FIGURE 1.3: CHANGE IN THE PERCENTAGE OF HOUSEHOLDS RELIANT ON
SOLID FUELS FOR COOKING IN ASIA AND THE PACIFIC
Source: Adapted from data available from State of Global Air 2018 (stateofglobalair.org)

18

impacts associated with these exposures, while
not yet fully understood, are currently treated in thesame way as those from air pollution in industrializedcountries where most of the epidemiological studies
have been performed. There is a need for a better
assessment of the health impacts of this dust, as
it could result in much lower burdens than thosefrom anthropogenic particulate matter (WHO 2016).
Further, during periods of intense atmospheric haze,initial mortality estimates indicate a potentially highburden (Koplitz et al. 2016). More research is neededon the health impacts of windblown dust and haze.
Health responses to air pollution vary due
to gender-linked biological differences andgender-based determinants of activity patterns
and exposure (Clougherty et al. 2010). Indoor
air pollution was estimated to be responsible for
4.3 million deaths in 2012 (WHO 2014); the mortality
associated with air pollution in 2016 by type of
air pollution in the Asia and Pacific region is shownin Figure 1.5. Indoor air pollution is gender-shifted
to women and young girls who tend to spend
more time indoors. This is particularly the casein Asian and African countries where genderroles are still observed – women are expected
to stay at home, take care of children or otherfamily members, and especially to prepare andcook meals (WHO 2016; Clougherty et al. 2010).

In poor rural areas of developing countries where
there is limited access to clean energy andalternative stoves, the main source of indoor air
pollution is cooking combustion, which produces
black carbon (BC), PAHs, PM2.5 and other toxic
pollutants. Women involved in cooking experiencesome of the highest levels of air pollution exposure(Balakrishnan et al. 2013a). Burning solid fuels forcooking is a major cause of mortality in low- andmiddle-income countries (Cohen et al. 2017) andin 2012, 60 per cent of all premature deaths fromindoor air pollution were observed in women andchildren (WHO 2016). In addition to substantial
health impacts associated with chronic exposure,
women also bear significant burdens associatedwith time spent in fuel collection as well as safetyconcerns associated with the use of solid-fuel stovesand during fuel collection (Bloomfield et al. 2015).
As women spend the most time exposed toindoor sources, they are at highest risk. If thewoman is pregnant, the risks are heightened andalso extended to the foetus, as proven by several
studies linking indoor air pollution with preterm
and low-weight births (Balakrishnan et al. 2017;
Malley et al. 2017; Amegah et al. 2014; Stieb et al.,2012; Shah and Balkhair 2011).

Deaths per 100,000 population
0–9
10–24
25–39
41–59
≥ 60

Data not available
Not applicable

FIGURE 1.4: AGE-STANDARDIZED DEATHS PER 100,000 PEOPLE ASSOCIATED
WITH AIR POLLUTION, BY COUNTRY, 2012
Source: adapted from WHO 2016

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

19

Consequently, young children staying in the house,or strapped to their mothers, are also exposed
to hazardous indoor pollutants. According to the
WHO (2016), exposure to indoor air pollution canalso be strongly influenced by cultural attitudes
towards gender: in general girls spend more timein the kitchen (e.g. Armstrong and Campbell
1991) but there are cultural exceptions, forexample, boys in India have been shown to becared for longer, spending more time in the
kitchen and therefore have higher chances ofdeveloping acute respiratory infections (Matinga
2010; Mishra 2001).
The gender paradigm for indoor air pollution healthimpacts is very much coupled with socio-economic
status and cultural influences, with women
generally spending more time indoors and thus
being at the greatest potential risk. Women are,however, also key in alleviating the problem fortheir families and themselves. Education can

encourage them to choose the less polluting
stoves and fuel, or position stoves to maximize
smoke/pollutant dispersion.
Beyond the direct effects of indoor air pollution on
exposure and human health, a growing body ofevidence indicates that it has substantial impacts
on ambient air pollution. This evidence – basedlargely on modelled estimates, though backed up
by source apportionment and other evidence –indicates that a substantial portion of ambient air
pollution arises from indoor sources, though there
is wide global heterogeneity. In India, for example,
seven evaluations of the contribution of households
to ambient air pollution estimate it at 22–52 per cent(Conibear et al. 2018; GBD 2018b; Butt et al. 2016;
Silva et al. 2016; Lelieveld et al. 2015; Chafe et al.
2014; see also http://www.urbanemissions.info/). A
2016 estimate from the Health Effects Institute (HEI),
based on the methodology of the GBD study (GBD
2015b), showed that 25 per cent of deaths attributed

Viet Nam
Vanuatu
Tonga
Timor-Leste
ThailandSri Lanka
Solomon Islands
Singapore
Samoa
Philippines
Papua New Guinea
Pakistan
Democratic Republic of Korea
New Zealand
Nepal
MyanmarMongolia
Marshall Islands
Maldives
Malaysia
Laos
Iran
Indonesia
India
Fiji
Federated States of Micronesia
China
Cambodia
Brunei
BhutanBangladesh
Afghanistan

Risk factor
Ambient ozone pollution
Ambient particulatematter pollution
Household air pollution
from solid fuel

0

50

100
150
Deaths per 100,000 people

200

250

Note: there is some overlap between indoor and ambient air pollution.

FIGURE 1.5: MORTALITY ASSOCIATED WITH AIR POLLUTION IN THE ASIA AND
PACIFIC REGION, BY COUNTRY, 2016
Source: adapted from GBD Compare, IHME 201720

to PM2.5 exposure – nearly 270,000 – arise from thecontribution of households to ambient pollution.
According to these estimates, household biomassburning was the largest single contributor to ambient
air pollution in India. Similarly, the HEI reported that for
China, household solid fuel combustion contributed
to approximately 177,000 deaths in 2013 and was animportant contributor to ambient air pollution (GBD2016). These findings, along with those from otherstudies relating household air pollution to ambient
air pollution, indicate that cleaning up household
combustion will be required to substantially
improve global ambient air quality.
1.2.4.2 Regional studies on the health effectsof air pollution
Much of the current evidence used for assessmentsof the disease burden related to air pollution
relies on long-term cohort studies mostly
conducted in North America and Europe overmultiple years. This evidence is included in the
IER approach to estimate excess risks (Cohenet al. 2017; Burnett et al. 2014) of mortality andmorbidity associated with exposure to PM 2.5.
However, even prior to the development ofdisease burden assessment methods, time-series
studies of the effects of short-term exposure(days to weeks) on morbidity and mortality fromcardiovascular and/or respiratory diseases haveprovided consistent evidence of the adverse
health effects of air pollution, informing policies
in North America (Samet et al. 2000; Greenbaum2001) and Europe (Samoli et al. 2008). Based on
this experience, a growing number of time-series
studies have also been conducted in Asia andreported in meta-analyses and reviews (Atkinson
et al. 2011; HEI 2010) as well as in findings fromlarge and coordinated multi-city studies that have
explored associations between exposure to air
pollution and cardiovascular, respiratory and otheroutcomes (Siddharthan et al. 2018; Yu et al. 2018;
Chen et al. 2017a; Wong et al. 2016a, 2016b; Yinet al. 2017a, 2017b, 2017c; Yorifuji et al. 2015;
Dholakia et al. 2014; Balakrishnan et al. 2013b;
Nishiwaki et al. 2013; Qian et al. 2013; Yorifuji et al.
2013; Rajarathnam et al. 2011; Kumar et al. 2010;
Kan et al. 2008; Vichit-Vadakan et al. 2008; Wonget al. 2008).

The meta-analysis of time-series studies in Asia
(Atkinson et al. 2011) identified 115 studies thatfound consistency between the risk estimates for
short-term air pollution exposure, mortality andmorbidity reported in Asian studies and studies inother parts of the world (Pope and Dockery 2006)(Figure 1.6). This finding is both remarkable andimportant given the substantially greater annual
average particle concentrations found in the large
Asian cities compared to North American andEuropean cities. Similarly, the results for short-term
O3 exposure align broadly with those from otherparts of the world (Figure 1.7).
A recent multi-city assessment in China (Yinet al. 2017c) estimated the associations between
PM10 concentrations and daily mortality fromcardiorespiratory and non-cardiorespiratory
diseases and all other causes for 38 large cities
in China, with mean daily PM10 concentrations
across all cities of 92.9 µg/m3. Meta-analyses
suggested that on average a 10 µg/m3 increasein concurrent-day PM 10 was associated with
a 0.44 per cent increase in the daily numberof deaths, a result that is comparable to otherlarge-scale meta-analyses involving some 33
other independent time-series and case cross-overstudies in China (Shang et al. 2013). PM10 had
a larger impact on people with cardiorespiratory
diseases, the old and women. The PM10 effectalso depended on demographic socio-economic
conditions in different cities.
Finally, a recent Chinese prospective cohort study,
one of the first in Asia, of nearly 190,000 men over
the age of 40 used the annual average PM2.5 levels
developed for the GBD 2013 study to estimate riskof non-accidental cardiovascular disease, chronic
obstructive pulmonary disease and lung cancer
mortality. The study compared its results with the risk
estimates predicted by the IER function built largely
on North American and Western European data.
The study found that long-term exposure to PM2.5
was consistently associated with non-accidental
mortality, cardiovascular disease, lung cancer andchronic obstructive pulmonary disease mortality in
China. It was one of the first to address exposure
across both urban and rural settings. The study
reported that the IER estimator may underestimate

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

21

22
1.5

1

0

Source: HEI 2010 and references therein-.524-hour
PAPA meta-analysis

PAPA meta-analysis

Multi city studies

8--hour

11 Canadian cities (Burnett 1998)

90 US cities (Bell 2004)

24-hour

24-hour

6 US cities (Ito 2005)

9 French cities (Le Tertre 2002)

24-hour

8--hour

3 Spanish cities (Saez 2002)

23 European cities (Gryparis 2004)

8--hour

Meta-analysis

8--hour

144 estimates (Bell 2005)

24-hour

15 estimates (Anderson 2004)

024-hour*.5
4 estimates (Levy 2001)

224-hour*

15 estimates (Stieb 2003)

7 estimates (Thurston 2001)

PAPA, Combined Analysis, 4 Asian cities (PM10)(Wong et al. 2008)

APHENA, 22 European cities (PM10)(Katsouyanni et al. 2009)

APHENA, 12 Canadian cities (PM10)(Katsouyanni et al. 2009)

APHENA, 90 U.S. cities (PM10)(Katsouyanni et al. 2009)14 U.S. cities case-crossover (PM10)(Schwartz 2004)

10 U.S. cities (PM10)(Schwartz 2000; Schwartz and Coull 2003)

9 Californian cities (PM2.5)(Ostro et al. 2006)

6 U.S. cities (PM2.5)(Klemm and Mason 2003)

18 Latin American studies(PM10) (PAHO 2005)

ALR quantitative analysis, 15 Asian cities (PM10)(HEI International Scientific Oversight Committee 2010)

Publication bias adjusted (PM10)(Anderson et al. 2005)

Unadjusted (PM10)(Anderson et al. 2005)

Non GAM-based studies(PM10)(Stieb et al. 2002, 2003)

GAM-based studies(PM10)(Stieb et al. 2002, 2003)

29 cities (PM10)(Levy et al.2000)

1.7
1.6
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0

24-hour*

24-hour*

Increase in mortality (%)

Increase in mortality (%)

Estimates from meta-analyses
Estimates from multicity studies

Per 10 μg/m3 increase in PM

Note: recent understanding of health impacts concerns PM2.5 and there is uncertainty converting between PM10 and PM2.5.
In the absence of PM2.5 studies, PM10 studies show similar results for Asia and the rest of the world.

FIGURE 1.6: COMPARISON OF PM10 RESULTS FROM US AND EUROPEAN META-ANALYSES,MULTI-CITY STUDIES AND ASIAN SYSTEMATIC REVIEWS

Source: HEI 2010 and references therein

PAPA studies

Note: the random effects estimate for all-causes mortality was 0.07 per cent (95 per cent confidence interval,−0.16 per cent, 0.30 per cent) per 10 μg/m3 increase in O3 over eight hours.

FIGURE 1.7: COMPARISON OF INCREASES IN MORTALITY FROM OZONE RESULTS
FROM US AND EUROPEAN META-ANALYSES, MULTI-CITY STUDIES,AND THE ASIAN SYSTEMATIC REVIEWS

mortality due to the long-term exposure to PM2.5
over the higher exposure ranges experienced in
China and other low- and middle-income countries(Figure 1.8).

While most health burden assessments, including
the GBD, utilize the most recent accessible datasetson mortality and disease incidence as provided or
corroborated by in-country collaborators, in many
instances these are limited by the completenessand accuracy of the available datasets. Improvementin the disease and cause of death registries cansubstantially reduce uncertainties in burden
assessments at the national and regional scales.

from studies primarily of areas outside theregion. However, there is a need to undertake
more epidemiological studies, such as cohort
studies, for O3 and PM2.5 in Asia, and to address
potential uncertainties resulting from underlying
region-specific differences in ethnicity; pollutant
mixtures, including the role of wind-blown dust
in many countries; nutritional status; and otherdisease-specific co-variates. This will greatly
enhance the accuracy of the risk estimatesobtained from exposure-response relationships.
Furthermore, improvements in locally available
mortality and morbidity datasets are crucial
in being able to improve on health impact
estimates that currently attribute millions ofpremature deaths to air pollution in Asia.

Considering differences in ethnicity, lifestyle, therole of windblown dust, season and weather,amongst other factors, between the Asian andEuropean/American regions, it is especially
important to select the appropriate exposureresponse function. There is considerable
consistency between the risk estimates obtained
from short-term epidemiological studies for PM2.5
and O3 in Asia and those currently available

The Global Burden of Disease methodologies, forexample of WHO, IHME and Environmental Benefits
Mapping and Analysis Program of the USEPA(BENMap), play a key role in identifying the factorsthat contribute most to disease and mortality – thefirst step towards identifying what can be done toimprove public health. Among the 79 risk factors
included in its comprehensive analysis, the GBD
project reported that exposure to ambient and indoor

1.2.5 State of knowledge and uncertainty

3.6
3.4

Hazard ratio (95% confidence interval)

3.2
3
2.8
2.6
2.4

Present study

2.2

IER predictions

2

Meta analysis

1.8
1.6
1.4
1.2
1
0.8

Ischaemic
heart disease

StrokeChronic obstructive
pulmonary disease

Lung cancer

Note: Hazard ratios are calculated based on exposures at the 5th (15.5 ug/m3) and 95th (77.1 ug/m3) percentile using
three methods/data sources: Yin et al. 2017a, IER predictions (Cohen et al. 2017), and previous Meta analysis.

FIGURE 1.8. COMPARISON OF CAUSE-SPECIFIC HAZARD-RATIO ESTIMATES:IN A STUDY OF CHINESE MEN OVER THE AGE OF 40
Source: Yin et al. 2017a

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

23

air pollution from PM2.5 was the highest-ranking risk
factor among environmental factors contributing
to mortality. Furthermore, the use of solid cooking fuels
can have significant gender- and livelihood-related
impacts for women, in addition to the direct healthimpacts. The GBD project has also laid out thecritical interplay between trends in population
structure, underlying disease, economic factors
and trends in air pollution. Knowledge of thesetrends is essential for understanding patterns
in the burden of disease experienced by the
populations of different countries and regions andfor helping to inform decision makers on where
policy action to reduce population exposure at thenational or regional level has the most potential toprovide large benefits in improved health.
There are methods for estimating disease burdens
associated with risk factors such as air pollution
and for comparing these estimates with those madefor other risks. While a specific exercise for the Asia
and Pacific region would be best for guiding policy
decisions, there is currently not enough data fromthe region, especially epidemiologic data of thetype needed, to associate exposure to air pollution
with various health outcomes. Thus, while the lackof region-specific data leads to some uncertainty,
this should not prevent immediate action tocontrol air pollution, especially in light of the large
and consistent global evidence base.
Further, the broad consistency in results fromshort-term health effects studies conducted acrossNorth America, Europe and Asia and newly reported
long-term cohort studies from China provide avery coherent argument for large and dual healthburdens from ambient and indoor air pollution
in the region. China and India have also recently
launched sub-national – provincial or state level –burden of disease assessments using the GBD
approach (India State-level Burden of Disease
Collaborators 2017), indicating a broader willingness
for governments in the region to use the GBD
approaches to foster air quality action.
The differences between alternative modelling
approaches are minor in the face of the large
burdens that confront populations. The preceding
sections provide a compelling rationale for
acknowledging the imminent need for air quality
action in most countries in the region. This section

24

is intended to serve as a prelude to the modelling
efforts described in Chapter 2 that compare andcontrast multiple scenarios of air quality actionthat can result in health gains.
1.2.6 Conclusions• According to recent estimates, each year		 7 million premature deaths worldwide are		 attributable to exposure to ambient and		 indoor air pollution, with the rapidly developing		 countries in Asia and the Pacific bearing much		 of this burden.

• Around 1.9 billion people living in Asia depend
		 on burning solid fuels for cooking and heating,		 which is a major cause of mortality in low- and		 middle-income countries with women and		 children particularly affected.
• A number of studies indicate that reducing
		 emissions from household cooking and		 heating may also be required to substantially		 improve ambient air quality in some parts of
		 Asia and the Pacific.
• The total mortality burden from indoor and		 ambient air pollution is ranked fourth behind		 dietary risks, tobacco and high blood pressure.
		 In 2013, it was estimated that exposure		 to ambient and indoor air pollution cost the		 world’s economy about US$ 5.11 trillion in		 welfare losses. In South and East Asia this cost		 is equivalent to 7.4 and 7.5 per cent of their
		 GDP respectively.
• An expanding body of evidence points to a		 number of areas of growing concern, including
		fer tility and bir th-related outcomes		 neurocognitive effects and diabetes related to		 exposure to air pollution.
• In 2016, the population-weighted annual mean
		 concentration of PM2.5 in the Asia and Pacific		 region was estimated to be 58 μg/m3, with a		 majority of the population living in areas
		 exceeding the WHO Interim Target 1 of 35 μg/m3.
• There is considerable consistency between
		 the risk estimates obtained from short-term
		 epidemiological studies for PM2.5 and O3 in		 Asia and those currently available from		 studies primarily of areas outside the region.

• There is a need to undertake more epidemiological		 studies, such as cohort studies, for O3 and		PM 2.5 in Asia, and to address potential
		 uncertainties resulting from underlying		 region-specific differences in ethnicity and		 pollutant mixtures, including the role of		 wind-blown dust in many countries.

1.3 AIR QUALITY AND CLIMATE
1.3.1 Introduction
Air quality and climate change are closely related(Fiore et al. 2015; Fuzzi et al. 2015; Monks et al. 2015;
Stohl et al. 2015; von Schneidemesser et al. 2015;
Shindell et al. 2012; UNEP/WMO 2011; Isaksen etal. 2009). Key greenhouse gases, such as carbon
dioxide (CO2) and methane (CH4), and air pollutants
including short-lived climate pollutants (SLCPs),
share many emission sources and are often emitted
together from the same tailpipe or smokestack, forexample diesel vehicles and coal plants. It is thus
widely recognized that improving air quality can makea sizable contribution to tackling climate change
problems, for instance fuel efficiency improvements
decreasing air pollutant and CO2 emissions.
Future changes in climate are known to affect air
quality by influencing the formation and removal
processes of ground-level O3 (Figure 2, Introduction)
and aerosols through changes in temperature,
precipitation, other meteorological conditions andprecursor concentrations (Allen et al. 2016; Jacoband Winner 2009). Links between air quality andclimate change are immensely complex and an
active area of scientific research.
Understanding the interplay between air quality
and climate change is key for designing integrated
policies and plans that maximize air quality andclimate co-benefits. This section focuses on thephysical and biogeochemical aspects of suchconnections. Section 1.3.2 provides a short overview
of how air pollution influences global climatechange. The impacts on the Asian cryosphereand monsoons are discussed in sections 1.3.3
and 1.3.4, respectively. The climate impacts on
air pollution are described in section 1.3.5 andclimate-related discussions on SLCP mitigation
strategies and issues associated with interactions
between climate and air quality policies in section
1.3.6. Conclusions are given in section 1.3.7.
Regional haze in different parts of Asia and winterfog in South Asia are introduced in Boxes 1.2 and1.3 respectively.
1.3.2 Global climate impacts of air pollutants
There is a wealth of evidence that anthropogenic
emissions of aerosol particles, such as BC andorganic carbon (OC), and gaseous pollutants suchas sulphur dioxide (SO2), CO, VOC and oxides ofnitrogen (NOx), that act as precursors for theatmospheric formation of O3 and secondary aerosol
particles, affect the climate (IPCC 2013; Myhre etal. 2013b). As well as affecting climate, secondary
aerosol particles formed in the atmosphere,
such as organic, sulphate, nitrate and ammonium
aerosol, are also important components of PM2.5
affecting human health (section 1.2) and ecosystems(section 1.4).
Ozone is formed in the atmosphere from theinteraction of CO, NOx, CH4 and VOCs in the presenceof sunlight (Figure 2, Introduction). Methane isitself a strong greenhouse gas, as is O3, adding
to the warming of the atmosphere. The other O3
precursors – CO, VOCs, NOx – do not directly influence
the climate but do so indirectly by contributing
to the formation and depletion of tropospheric
O3 and CH4 (Myhre et al. 2013b).
Aerosols affect the climate through several key
mechanisms. They directly impact the climate
by scattering, for instance by sulphate andorganic aerosols, or absorbing, for example by
BC aerosols, incoming radiation from the sun andoutgoing radiation from the Earth. They indirectly
influence the climate by changing cloud properties–cloud droplets, cloud reflectivity and lifetimes.
Furthermore, light-absorbing aerosol particles,
when deposited on snowfields and glaciers, makethe surface darker, changing the surface albedo,
with the result that more sunlight is absorbed,
affecting climate and the melting of snow andglaciers (section 1.3.3). Although uncertainties
are large, it is well established that, at the global
scale, the net effect of total aerosols is cooling(Boucher et al. 2013).

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25

With the notable exception of CH4, which is globallydispersed, the air pollutants discussed here are notwell-mixed at the global level; they remain moreconcentrated in and around the source region,
meaning that their climate impacts depend on thelocation of emissions (Collins et al. 2013; Lundet al. 2012; Berntsen et al. 2006). Note also thatthe focus here is on air pollutants emitted byhuman activities because of direct policy relevanceto reducing emissions and impacts; no naturalemissions are covered unless required. It should,
however, be noted that natural aerosols also affectthe climate directly or indirectly as mentioned
above (Carslaw et al. 2013).
The rest of section 1.3.2 provides an overview ofcurrent understanding of the radiative forcing andtemperature impacts of air pollutants at the global
level. The following components of air pollution
are considered in this section: gaseous species– CO, VOCs, NOx, NH3, CH4 and tropospheric O3;
and aerosols – sulphate, nitrate, ammonium, BC,
brown carbon (BrC), other OC and secondaryorganic aerosols (SOA). While radiative forcing ona species level is discussed, when it comes to themeasures explored in Chapter 3, it is important
to consider the net effect of the mix of species
emitted together, such as BC and OC co-emitted
from biomass burning. Hydrofluorocarbons (HFCs)
are also included in this report. Although HFCs are
not regarded as air pollutants, they are emitted insignificant quantities and have a considerable impact
on climate forcing (warming) (Figure 1.9 and Box 1.1)
1.3.2.1 Radiative and temperature impacts ofdifferent pollutants
The present knowledge of the global magnitude ofradiative forcing of each component is shown in
Figure 1.9. Radiative impacts of gaseous pollutants– CO, non-methane volatile organic compounds(NMVOCs), and NOx – are generated indirectly
through changes in tropospheric O3 and CH4 via
hydroxyl radical (OH) chemistry (Monks et al. 2015;
Stevenson et al. 2013). Carbon monoxide and VOCemissions result in an increase in tropospheric
O 3 and CH 4 concentrations as well as CO 2
concentrations through oxidation, leading towarming. Conversely, the temperature impact of NOxdepends on the timescale of interest (Figure 1.10).

BOX 1.1: HYDROFLUOROCARBONSHydrofluorocarbons are a group of powerful factory-made greenhouse gases used primarily forrefrigeration and air conditioning. Production, consumption and emissions of HFCs have been
growing at a rate of 10–15 per cent per year, causing a doubling every five to seven years. This rapid
growth is due to their use as replacements for O3 depleting substances, which are being phased
out under the Montreal Protocol, as well as increasing demand for consumer air conditioning andrefrigeration. The Asia and Pacific region is one of the most significant drivers of both the demand
for and supply of HFCs globally.
The use of HFCs in residential air conditioning systems has experienced significant growth overthe past decade. Under current trends, an additional 700 million air conditioning units will be added
to the global stock by 2030, and 1.6 billion by 2050. This rapid growth has significant implications
for future HFC emissions as well as energy security and air pollution from energy generation, as air
conditioning accounts for a significant percentage of peak energy loads in hot climates.
Many HFCs remain in the atmosphere for less than 15 years. Though they represent a small fractionof current total greenhouse gases (less than 1 per cent), their warming impact is particularly strong
and, if left unchecked, they could account for nearly 20 per cent of climate pollution by 2050.
A recent study concluded that replacing HFCs that have high global warming potential (GWP) with
low-GWP alternatives could avoid 0.1ºC of warming by 2050.

26

Components of radiative forcing

CH4
CO2

Halocarbons

CH4

NO2

O3

HFCs–PFCs–SF6

H2O (Strat.)

CO

Short-lived gases

Well mixed GHG

CO2

NMVOC
NitrateNOx
NitrateNH3

Aerosols and precursors

Sulphate

BC on snow

Fossil andbiofuelSO2Black carbon
Organic carbon

Biomassburning-1.2

OthersSulphate

Mineral dust

ERF aci

Aerosol – cloudContrails

Aircraft

Surface albedo

Land use
Solar irradiance

-0.5

0.0

0.5

1.0

1.5

Radiative forcing (W/m2)

CO2 – carbon dioxide

NOx – nitrogen oxides

CH4 – methane

NH3 – ammonia

HFCs – hydrofluorocarbons

SO2 – sulphur dioxide

PFCs – perfluorocarbons

BC – black carbon

SF6 – sulphur hexafluoride

ERF aci – effective radiative forcing (ERF)

HCFCs – hydrochlorofluorocarbons

aerosol – cloud interactions (aci)CO – carbon monoxide

W/m2 – watts per square metre

NMVOCs – non-methane volatile organic compounds

GHG – greenhouse gas

FIGURE 1.9: PRESENT MAGNITUDES OF THE RADIATIVE FORCING OF AIR POLLUTANTS,
CLIMATE FORCERS AND OTHER CHANGES FOR THE PERIOD 1750–2011
Source: IPCC 2013 (Figure 8.17)

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27

Temperature impact (10-3K)

20

CO2
CH4

BC

10

CO

N2O

0
NOx

OC
-10
SO2

-20

-30
0

20

40
Time Horizon (yr)6080Note: 2008 is year 0.
The figure shows how some components have strong short-lived temperature effects of both signs while CO2
has a weaker initial effect but one that persists to create a long-lived warming effect.

FIGURE 1.10: TEMPERATURE RESPONSE BY COMPONENT FOR TOTALANTHROPOGENIC EMISSIONS FOR A 1-YEAR PULSE
Source: Myhre et al. 2013b (Figure 8.33)

Emissions of NO x increase tropospheric O 3
concentrations on short timescales (warming)but decrease the CH4 concentration on decadal
timescales (cooling) (Shine et al. 2005; Wild et al.
2001). Furthermore, NOx emissions lead to theformation of nitrate aerosol, which leads to cooling.
Methane itself is the second strongest greenhousegas after CO2 in terms of direct radiative forcing,but it also has an indirect radiative forcing effect byproducing tropospheric O3 (more warming).
As mentioned earlier, aerosols affect the radiative
budget in the climate system in two ways (Myhre etal. 2013b): by scattering or absorbing the solar andthermal radiation (aerosol-radiation interactions), andby altering cloud properties and lifetimes (aerosolcloud interactions). The first type of interactions foreach species, which cause distinctive and sometimes
opposing impacts, are mainly described here. The
second aerosol-cloud interactions are known to
produce negative impacts collectively, albeit withlarge uncertainties (Figure 1.9).
Emissions of gaseous SO2, are precursors of sulphate28

aerosols that reflect the incoming radiation backto space, cooling the Earth’s surface and partly
masking present global warming (Andreae et al.
2005). Nitrate aerosols are formed through theoxidation of NOx, contributing to cooling. Formationof nitrate aerosols is closely related to the availabilityof NH3 and SO2 (Seinfeld and Pandis 2016; Behera
et al. 2013), and it is therefore important to consider
NOx, NH3, and SO2 simultaneously in clean air
policies (Heo et al. 2016; Pinder et al. 2007). The
magnitude of cooling from total ambient aerosols,with sulphate aerosols being most dominant, is,however, highly uncertain (Figure 1.9). Aerosol
forcing uncertainties give rise to one of the major
uncertainties in global climate projections on
decadal and centennial timescales (Armour andRoe 2011; Tanaka and Raddatz 2011; Knutti 2008;
Andreae et al. 2005; Harvey and Kaufmann 2002).
Another species of aerosol known to significantly
influence global temperatures is BC. It is generally
considered that BC contributes to warming, although
this is the subject of debate and uncertainty (Stjern
et al. 2017; Bond et al. 2013; Myhre et al. 2013a),

carrying important implications for SLCP mitigation
strategies (section 1.3.6). Black carbon warms
the climate mainly through the direct atmosphericheating of solar radiation absorption and the reduction
in surface albedo caused by deposition on snow
and ice; the warming effects of BC outcompete thecooling effects from other processes – scattering,
cloud albedo and cloud lifetime effects. Black
carbon warming depends on its location in air:it warms the layers of the atmosphere where it islocated, but that can cool the surface underneathby reducing the energy reaching the surface.
There are several other aerosol species that
influence global temperatures. Some OC aerosolsthat are normally emitted with BC from common
sources, for example biomass burning and peat
fires, contribute to cooling. Brown carbon, a fractionof OC that absorbs solar radiation, has recently
been recognized (Laskin et al. 2015) as a classof compounds that may positively revise the net
radiative forcing due to organic aerosols (Fenget al. 2013). Secondary organic aerosols accountfor a substantial fraction of total aerosols in theatmosphere (Zhang et al. 2007), but are not includedin Figure 1.9 because their formation depends on
factors that are yet to be sufficiently quantified.
In summary, this section introduced the radiative
and temperature impacts of air pollutants,
highlighting the diversity in magnitudes, timescales
and pathways of such impacts. It needs to be kept
in mind that the radiative forcing of air pollutants
is generally uncertain because of a variety ofmechanisms involving a suite of chemical species
operating on different spatial and temporal
timescales. The net effect of these impacts on the
climate is, however, generally understood within
accepted uncertainty bounds (IPCC 2013).
1.3.2.2 Effects on precipitation
Changes in temperature and incoming solar
radiation affect global precipitation by altering
the hydrological cycle. Precipitation impacts are
generally more uncertain than global temperature
impacts. A robust precipitation response towarming, caused by greenhouse gas emissions
or a decrease in light-scattering aerosols, is that
global precipitation increases by 1–3 per centper degree centigrade (°C) of warming (Held andSoden 2006). Another robust response with regard
to precipitation patterns is that wet areas becomewetter, while dry regions become drier (Samset et al.
2018; Samset et al. 2016; Allen and Ingram 2002).
Precipitation responds differently from warming
when it is caused by absorbing BC and BrC
aerosols because of different mechanisms
involving direct atmospheric heating (Andrews
et al. 2010; Ming et al. 2010). Both light-absorbing
and light-scattering aerosols such as sulphateaerosols decrease global precipitation even thoughtemperature responses are the opposite. It should
also be noted that the responses vary acrossregions (Stjern et al. 2017) (section 1.3.4).
1.3.2.3 Effects on other aspects of climate
There are other mechanisms through which air
pollutants influence the climate, namely throughbiogeochemical cycles (sections 1.4.3 and 1.4.4).
For example, an increase in the O3 concentration
due to precursor emissions adversely affects
vegetation, effectively reducing carbon uptake, andresults in more CO2 emissions to the atmosphere,
resulting in warming (Arneth et al. 2010). Aerosols
affect the climate through physical impacts on
ocean and land biospheres and through directly
depositing relevant elements in the element cycles,
providing, when all combined, positive feedbacks to
climate (Mahowald 2011). An example of the first
type of feedback is that light-scattering aerosols
can increase diffuse radiation, which enhances
the biological productivity over land, thereby
decreasing atmospheric CO2 (Mercado et al. 2009)(Section 1.4.4).
1.3.3 Impacts on the Asian cryosphere
The glaciers and snowfields of the Hindu Kush,
Karakoram, Himalayas and Tibet (HKHT) containthe largest amount of frozen water outside thepolar regions. The region serves as a natural water
reserve for more than 1.4 billion people living
in downstream river basins (Vaux et al. 2012;
Immerzeel et al. 2010; Barnett et al. 2005). Thereis growing evidence of high-altitude warming in the
HKHT region, with multiple studies reporting theretreat of high mountain glaciers and early spring

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29

snow melt across the Himalaya region (IPCC 2007;
Kulkarni et al. 2007). There are several reasons
behind the increasing rate of glacial retreat in thecentral and western Himalayas in recent decades(Raina and Sangewar 2007; Jain 2008), including
air pollutants, mainly BC and mineral dust (Bolch
et al. 2012; Qian et al. 2011; Menon et al. 2010;
Flanner et al. 2009).
Air pollution impacts on the cryosphere – snow,
ice and frozen ground – in Asia are an importantregional issue. Deposition of light-absorbing
aerosols – mineral dust and BC – over the glaciersand snowfields can accelerate snow and ice melt
and thus cause the retreat of mountain glaciers(Gul et al. 2018; Qian et al. 2015; Doherty et al.
2013; Painter et al. 2010). In addition, heating of theatmosphere by light-absorbing species can cause
extensive enhanced warming and also contribute toaccelerated melting of glaciers. This is the reason
why BC is thought to play an important role in the
rapid retreat of Himalayan-Tibetan Plateau glaciers(Yao et al. 2012). The Himalayas-Tibetan region isaffected by BC emissions from South Asia, East
Asia, West Asia and Europe as well as from within
the region itself (Li et al. 2016; Lu et al. 2012; Babu
et al. 2011). According to the 2012 results of Lu etal. (2012), BC received by the Himalayan-Tibetan
Plateau increased by 41 per cent from 1996 to2010, implying that the BC problem is acceleratingin the region. South and East Asia are the main
source regions, accounting for 67 per cent and 17
per cent respectively of BC transported to HKHT on
an annual basis, with minor contributions from theMiddle East, ˜4 per cent; Europe, ˜2 per cent; andNorthern Africa, ˜1 per cent. However, several recent
studies show that the impact of internal Tibetan
sources (for example, yak dung combustion by
local residents) on the atmosphere of the Tibetan
Plateau should not be overlooked (Zhang et al.
2017). Dust particles from adjacent deserts anddry areas can also play important roles in snow
darkening. One study shows that the contributionof dust to snow darkening and albedo reduction
on the Zhadang glacier on Mt. Nyainqentanglha
in Tibet can reach up to 56 per cent, much higher
than the effect of BC of 28 per cent (Qu et al. 2014).
This has repercussions for water resources
downstream: additional discharge of water, rises in30lake levels, more frequent glacial lake outburst floods(GLOFs) and risks associated with such floods, asreported by many studies (Sun et al. 2018; Xiao et al.
2008; Ye et al. 2008, 2007; Yao et al. 2007, 2004).
It is generally agreed that light-absorbing aerosols
are the cause of accelerated glacier melting;however, their contributions and that of greenhousegas-induced warming are yet to be better quantified(Bolch et al. 2012). That needs a more integrated
approach using Earth system high-resolution
modelling and more reliable observational datasets,
including satellite data.
1.3.4 Precipitation and the Asian monsoon
In addition to deteriorating air quality, the increasing
trend of floods and droughts in Asian monsoon
regions poses a severe threat to the 60 per centof the world’s population living in those regions
as well as to the fragile ecosystems wheremonsoon rains are considered the main sourceof water for arable lands. The increasingly erratic
nature of the monsoon can cause loss of lives
and destruction of farmlands, damage livelihoods
and property and incur extensive financial loss
(Yi et al. 2015).
Aerosols over these monsoon regions can alter
rainfall patterns (Lau and Kim 2006; Menon et al.
2002; Ramanathan et al. 2001). Weaker trends in
Indian monsoon precipitation and a north-south
shift in precipitation in East Asia have been observed(Cowan and Cai 2011; Menon et al. 2002) thathave been linked to changes in the emissions ofaerosols and other pollutants from within andoutside Asia (Ganguly et al. 2012).
The Asian monsoon shows a strong spatiotemporalvariability due to complex topography, diverse
emission sources, aerosol types and impacts ofaerosols and greenhouse gases. There are still
uncertainties in estimating impacts on Asianmonsoon patterns (Wu et al. 2012a, 2012b;
Ramanathan and Feng 2009; Wu et al. 2007).
Furthermore, global emissions from forest fires
and anthropogenic activities produce a warmer
stratosphere and relatively cooler troposphere (Minget al. 2010) for several reasons, such as reduced
convection in the lower troposphere.

BOX 1.2: REGIONAL HAZE AND DIMMING
Atmospheric aerosols lead to a major redistribution of solar forcing in the atmosphere and on thesurface (Figure 1.9). In the atmosphere, light-absorbing aerosols, particularly BC and BrC, result ina large positive radiative forcing compared to surface and top-of-the-atmosphere forcings. Thiseffect is known as atmospheric solar heating. At the surface, however, a dimming effect is observed(Figure 1.11): less sunlight reaches the surface because the aerosol mixture overhead reduces theamount of radiation reaching the Earth’s surface – BC and BrC absorb incoming solar radiation
while inorganic aerosols such as sulphate, nitrate and ammonium and other organic aerosols
reflect it. This leads to a negative radiative forcing, a cooling, at the surface. This redistribution ofheat as well as moisture is an important driver of observed changes in the Asian monsoon and thehydrological cycle (section 1.3.4.) Taken together, the summed effect of atmospheric solar heating
and surface dimming gives the top-of-the-atmosphere radiative forcing, which is the relevant termfor determining the effect on temperature change.
It has been estimated from simulations that South Asia’s atmosphere has warmed at the rate of 0.25°C
per decade since 1950 (Ramanathan et al. 2007). The reason behind the additional warming, besides
greenhouse-induced warming, is mainly the presence of BC content in haze over the Indo-Gangetic
Plains and nearby areas, including the Himalayan-Tibetan mountain regions, 2,000–5,000 metresabove sea level (Ramanathan and Carmichael 2008). Several glaciers and snowfields are located at
this altitude. Atmospheric heating induced by BC and its deposition on snow and ice are linked to theaccelerated observed retreat of the glaciers in the region (Ramanathan et al. 2007) (section 1.3.3).

W/m2

Note: uncertainty in the forcing is ±30 per cent.

FIGURE 1.11: SURFACE DIMMING DUE TO AEROSOLS FOR THE 2001–2003 PERIOD

Source: Ramanathan and Carmichael 2008

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31

1.3.5 Impacts of climate change on air quality
It is not only the case that air pollution affects
regional and global climate; climate change
will also have an effect on and consequences
for local and regional air quality and air quality
management. Changes in climate affect air quality
through several different mechanisms, the most
relevant of which include:
1. changes in temperature that affect chemical		 production and loss rates, most relevant for		O3 production,, and precursor emissions;
2. changes in local and regional circulation that		 lead to changes in dispersion; and;3. changes in precipitation that effect changes
		 in wet deposition of chemical species
		 (Jacob and Winner 2009).
A strong correlation is observed between temperatureand elevated O3 concentrations in polluted areas(Otero et al. 2016; Jacob and Winner 2009) – theso-called ‘climate penalty’. In the case of East Asia,
Lee et al. (2015) predict increases in annual average
maximum daily eight-hour O3 of 9 parts per billion(ppb) by the end of the century compared to the
2000s under their highest emissions scenario (IPCC
SRES A2). Their model study shows that for China
the change in O3 air quality is most dependent on
precursor emission changes, but that for Japan,changes in O3 air quality depend more on climatechange (Lee et al. 2015).
Understanding how particulate matter pollution
will change in a changing climate is complex andmore uncertain than in the case of O3. A global
study (Horton et al. 2014) predicted that changes
in atmospheric circulation driven by global
warming will lead to increases in the occurrenceof stagnation events over much of the globe,
including Asia, with particularly acute impacts
in India. Increased stagnation means increased
human exposure to air pollution because thepolluted air builds up at the surface instead ofbeing dissipated by winds and circulation.
Changes in precipitation are also expected to havea large impact on particulate matter concentrations
because wet deposition is the dominant removal
mechanism of particulate matter from theatmosphere. However, regional-level changes in32

precipitation under climate change, due togreenhouse gases or air pollutants, or both, remain
fairly uncertain, especially at the regional to local
level (Hartmann et al. 2013).
In a recent study of the city of Beijing, Cai et al.
(2017) predict that climate change will cause a
50 per cent increase in the frequency of weather
conditions conducive to winter haze episodes.
In addition, the persistence of haze-favourable
weather conditions is predicted to increase. These
local effects are attributed to large-scale circulation
changes induced by climate change, including
a weakening of the East Asian winter monsoon.
This study also implies a climate penalty for air
pollution in Beijing, where future climatic conditions
will require even greater reductions in emissions toreach air quality goals, as would also be the casetoday. Better understanding of how climate change
will affect particulate matter pollution on a regional
to local scale in different parts of Asia will require
more high-resolution and local studies.
1.3.6 The significance of short-lived climate
pollutant strategies
There is interest, as well as an increasing bodyof scientific studies, in jointly addressing air
pollution and climate change in policies that
promote measures that offer multiple co-benefits,
especially those cutting SLCP emissions (Shindell
et al. 2017; Maione et al. 2016; Akimoto et al. 2015;
Victor et al. 2015; Schmale et al. 2014; Shindell
et al. 2012; Williams 2012; UNEP 2011; UNEP/WMO 2011; Ramanathan and Xu 2010). Thesestudies show that swift and wide implementationof easily available solutions would lead to climate
benefits. Some studies report that half a degreeof warming can be avoided by 2050 through suchmeasures (Shindell et al. 2012; UNEP/WMO 2011).
Others indicate that climate benefits in terms of
reduced temperature may be limited (Stjern et al.
2017; Shoemaker et al. 2013). Further studies areneeded, however, to fully define the climate benefitsof SLCP mitigation.
In integrating the two perspectives, however, there
are also trade-offs that need to be considered tomake the most of potential synergies. The physicalaspects of such issues are discussed here, while

BOX 1.3: VISIBILITY AND WINTER FOG IN SOUTH ASIA
Moisture and cold temperatures alone are not enough to form fog; water vapour requires thepresence of particles on which to condense. Los Angeles, California saw a decrease in fog
as it cleaned up its air pollution problem and ambient aerosol concentrations dropped (LaDochy2013). Some cities in Asia have experienced the reverse: they have observed denser and more
persistent fog, partly due to increases in air pollution (Syed et al. 2012). Central and eastern China
have seen a doubling of fog frequency over the past three decades as aerosol concentrations
have increased (Niu et al. 2010).
In the Indo-Gangetic Plain, the increase in fog appears to be associated with the rising trends ofanthropogenic air pollution (Habib et al. 2006). In fact, the region covered with winter fog (Figure 1.12b)
has also been observed to have heavy aerosol loads in the atmosphere (Figure 1.12a).

(A)

(B)

FIGURE 1.12: (A) AEROSOL OPTICAL DEPTH ACQUIRED WITH MODISINSTRUMENT ONBOARD TERRA SATELLITE AND (B) MODIS IMAGE SHOWINGCLOUDS AND FOG OVER THE INDO-GANGETIC PLAIN ON 20 NOVEMBER 2017
Source: (a) Praveen et al. 2012; (b) NASAIn Delhi, the fog onset was found to match times of high aerosol concentrations as well as high CO
levels – a tracer of combustion (Payra and Mohan 2014; Mohan and Payra 2009). Field observation
at Delhi airport in winter 2015–2016 found that the fog occurred in a highly polluted environment
dominated by combustion and vehicular emissions (Ghude et al. 2017). During winter, aerosols
over the Indo-Gangetic Plain predominantly originate from biomass burning and agricultural wasteburning (Ram et al. 2011; Gustafsson et al. 2009). In Kanpur, a large fraction of measured organic
aerosols were found to be from biomass burning (Sarkar et al. 2013). Cold ground, stable air andlow wind speeds that accompany fog also trap pollutants near the ground and allow near-surfacebuild-up of pollution (Khokhar et al. 2015; Sharma et al. 2011).

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33

other dimensions including economics, regulatory
frameworks, implementation and institutions are
discussed in Chapter 3.
There are various differences between climatechange and air pollution that have potential for
creating trade-offs between the two sets of policies.
Broadly, while air pollution measures typically concern
local and regional scales on short timescales,
climate measures address global impacts on longtimescales. At the level of individual pollutants, themagnitudes and even the signs of climate impacts
differ between components, for example BC andSO2 (Figure 1.9). The timescales of radiative impacts
span a large range: the atmospheric residence
time of BC is days or weeks, for CH4 decades, andcenturies and millennia for CO2 (Joos et al. 2013;
Archer et al. 2009), leading to a variety of timescalesin temperature impacts (Figure 1.9). Furthermore,
uncertainties in climate effects are generally
very large.
Such diversity and uncertainty pose a challenge forlinking the two sets of policies. Benchmarking theclimate effects of air pollutants against those of CO2
is difficult, as evident in the decades-long debates on
emission metrics, an index to equate emissions of
non-CO2 components on the common scale of CO2(Myhre et al. 2013b; Johansson 2012; Fuglestvedt
et al. 2010; Tanaka et al. 2010; Shine 2009; O’Neill
2003; Manne and Richels 2001; Skodvin andFuglestvedt 1997; Lashof and Ahuja 1990). Becauseof the diversity in the atmospheric characteristics
of climate forcing agents, such benchmarking
depends critically on the assumed basis forcomparison such as the time horizon. In an attempt
to resolve these issues, new thinking has recently
been put forward to make use of multiple metrics
in order to better capture diverse climate impacts(CCAC 2017; Ocko et al. 2017; Cherubini et al. 2016;
Cherubini and Tanaka 2016; Levasseur et al. 2016a,
2016b). Such new approaches complement one
metric representing long-term impacts with anotheremphasizing short-term ones.
Lastly, it needs to be remembered that global climatechange is primarily caused by anthropogenic CO2
emissions. Short-lived climate pollutant
interventions focusing on BC, O 3 and HFCs
contribute to slowing global warming only inshort-term decadal timescales; urgent and34

strengthened measures for cutting CO2 emissions
are indispensable (Tanaka and O’Neill 2018) inparallel with SLCP interventions to solve global
climate change (Shoemaker et al. 2013; Shindell
et al. 2012; Berntsen et al. 2010).
1.3.7 Conclusions• Carbon dioxide and air pollutants share		 many emission sources and are often emitted
		 together from the same tailpipe or smokestack,		 giving potential for mitigation measures		 tackling air quality and climate change		 simultaneously to achieve multiple benefits.
		 Other air pollutants, such as BC, CH4, ground		 level O3 and HFCs, referred to as SLCPs,
		 affect the climate in the short-term (decadal		 timescales) and offer further benefits related		 to human health, crop yields and climate change.

• Emissions of air pollutants and aerosol/
		 particulate pollution precursors impact the		 climate at global scales and can influence		 precipitation, fog and haze formation and		 glacial melt at regional scales. There are		 several reasons behind the increasing rate of		 glacial retreat in the central and western
		 Himalayas in recent decades, including air
		 pollutants, mainly BC and mineral dust.

• A weaker trend in the Indian monsoon
		 precipitation and a north-south shift in		 precipitation in East Asia have been observed		 and linked to changes in the emissions of		 particles and other pollutants from within		 and outside Asia. However, there are still		 uncertainties in estimating the impacts of		 air pollution on the Asian monsoon due to the		 complex topography, diverse emission sources,
		 and a wide range of pollutants with potentially		 complex impacts.

• Future changes in climate are known to affect		 air quality by influencing the formation and		 removal processes of tropospheric O3 and		 aerosols/particulate pollution.

• There is an increasing interest in simultaneously		 addressing air pollution and climate change		 through policies to promote measures offering		 multiple benefits, especially those that aim to		 reduce emissions of SLCPs. Policies that focus
		 on reducing BC and ground-level O3 in the		 atmosphere contribute to slowing global
		 warming and reducing air pollution. These		 policies should, however, complement and		 not replace those reducing CO2.
• The links between air quality and climate		 change are complex and an active area of		 scientific research. Understanding the		 interplay between air quality and climate		 change is key for integrated policy making that		 can maximize air quality and climate benefits.

1.4 AIR QUALITY, AGRICULTURE ANDECOSYSTEMS
1.4.1 Introduction
This section considers the evidence of impactsof air pollution on agriculture and ecosystems
in Asia and the Pacific. It focuses on the major
air pollutants of concern: tropospheric O3, also
known as ground-level O3 (section 1.4.2); acidic
and eutrophying deposition (section 1.4.3); andparticulate matter (section 1.4.4) through acompilation of evidence from global and Asianstudies. The impacts of air pollution on the carbon
cycle are also considered (section 1.4.5).
Although not all the impacts reported in thissection will occur over the entire Asia and Pacificregion, areas with similar pollution levels and cropand ecosystem sensitivity are likely to experience
them. The section outlines the strength of theevidence base underpinning the modelling ofcrop-yield loss due to tropospheric O3 in Chapter
2, and also assesses evidence of other benefits
for crops and ecosystems, as well as possible
trade-offs, when action is taken to reduce air pollution.
Tropospheric O3 is widely recognized as the mostdamaging air pollutant to vegetation due to its
phytotoxicity and prevalence at high concentrations
over rural/agricultural regions, often locateddownwind of emission sources (Ainsworth
et al. 2012; Royal Society 2008). Exposure to
relatively low levels of tropospheric O3 – lessthan 40 ppb – are known to have negative effects
on crop productivity and natural ecosystems(Ainsworth 2016; Emberson et al. 2009).

Concentrations of tropospheric O3 have been
observed to follow increasing trends in bothlarge urban areas and their surroundings in Asiandeveloping countries (Wang et al. 2016; Ainsworth
et al. 2012; Nghiem and Kim Oanh 2009; Royal
Society 2008). Limited monitoring data on
suburban and rural O3 concentrations in Asia also
indicate that monthly mean O3 concentrations
now commonly reach 50 ppb during important
agricultural growing seasons (EANET 2016).
Four-week mean O3 concentrations, measured using
passive samplers, in the major agricultural regionsof Pakistan have been found to exceed 45 ppb(Ahmad et al. 2013). Ozone monitoring in the IndoGangetic plain of India reported daytime 12-hourlymean monthly O3 tropospheric concentrations
varying from 45–62 ppb during summer to
24–44 ppb during winter and rainy months (Mishra
and Agrawal 2015; Chaudhary et al. 2013; Tiwari
et al. 2008). Modelling studies at the regional andglobal scale (Ghude et al. 2014; Dentener et al.
2006) project that under current legislation
emission scenarios, parts of Asia will experience
further significant increases in tropospheric O3
concentrations by 2030. The implications of these
conditions for impacts to crops and vegetation in
the region are considered in section 1.4.2.
Other pollutants also have adverse impacts on
crops and ecosystems. Particulate matter and its
precursors, including those that are transported
over large distances – sulphate, nitrate andammonium particles – can cause adverse
effects on ecosystems and their biodiversity, forexample through excessive nutrient enrichmentof ecosystems and acidification, which canaffect crop production and important ecosystemservices (Duan et al. 2016; EEA 2014; Jones et al.
2014; Hicks et al. 2008). Important ecosystemservices include provisioning food, fibre, timber andmedicines; regulating freshwater flows, preventing
erosion and providing protection from extreme
climate events; supporting oxygen production andnutrient cycles; and providing opportunities forrecreation and tourism. The effect of air pollutantson ecosystems is particularly problematic for Asia
due to a number of factors that combine to enhance
the likelihood of damage (section 1.4.3).

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35

Atmospheric aerosol or particulate matter including
BC can alter the amount of solar radiation reaching
the Earth’s surface – known as global dimming – andcan also influence atmospheric and surface
warming through reflection/scattering and albedo
processes, respectively (section 1.3). These effects
can disturb photosynthesis, which is dependent upon
photosynthetically active radiation and temperature,and in turn influence plant growth and productivity(Burney and Ramanathan 2014). High levels ofparticulate matter have been reported in the Asia andPacific region (Hopke et al. 2008; Kim Oanh et al.
2006) that are well above those in developed countries
around the world; hence the effects of particulatematter on ecosystems may be substantial. Section
1.4.4 shows how particulate matter effects on
solar radiation can have both positive and negative
impacts on vegetation and that further studies in
the region are required to determine the true natureof the impact.
It is also worth noting that plants appear to beeven more sensitive to a number of air pollutants,
such as nitrogen dioxide (NO2), O 3 and SO 2,
than humans; hence even if compliance with
the WHO Guideline for protection of humanhealth is achieved as suggested in this report,
problems for crops and ecosystems may remain(Bell et al. 2011).
1.4.2 Ozone impacts on important crops andecosystems
1.4.2.1 Evidence of ozone impacts on crops andecosystems
Ozone is a strong oxidizing gas; once it entersa plant through the stomata it causes damage
through oxidative processes (Heath 2008) similar
to the oxidative stress caused by high and low lightintensities, drought and cold stress. The result isthat exposure to O3 can cause damage to foliage
and reduce pigment content in leaves, which affects
plant growth and yield (Tomer et al. 2015; Agrawal
et al. 2003); this can occur with or without visible
symptoms of injury.
Visible injuries due to O3 show as flecking andbronzing of the upper leaf surface (Figure 1.13). Other
consequences of O3 damage include reductions in

36

photosynthesis, alterations in carbon allocation andreduction in yield quantity and quality (Feng et al.
2015; Fuhrer 2009). Ozone can also affect forest(Sicard et al. 2016) and grassland productivity (Wei etal. 2007), but not many studies have been conducted
for these ecosystems in Asia (Feng et al. 2014).
Effects of ground level O3 on crops were firstobserved in North America and later in Europe(Fuhrer and Booker 2003) and these catalysed
more concerted efforts to conduct research toquantify impacts. When considering yield effects
alone, a seminal paper by Mills et al. (2007) gives
a good indication of the relative sensitivities of anumber of different crop species. This and otherreview papers, however, tend to include only very
few Asian studies since, until recently, empirical
data for the Asian region have been rather limited
and only collected by a few research groups.
The magnitude of response to O3 varies significantly
not only between crops – beans, for example, aremore sensitive than maize or rice (Mills et al.
2007) – but also amongst cultivars of the samecrop. For example, Japanese rice cultivars may
be less sensitive to O3 than other cultivars used inexperiments (Yonekura and Izuta 2017). Emberson
et al. (2009) suggested that the Asian-grown wheat
and rice cultivars may be more sensitive to O3 thantheir North American counterparts. Likewise, Sinha
et al. (2015) suggested that the Indian rice and wheat
cultivars appeared to be more sensitive to O3 than are
their European and Southeast Asian counterparts.
It is important to note that the climate regime
and management practices that vary globally arealso likely to influence crop and, potentially, forest
sensitivity to O3 (Luo et al. 2013; Chen et al. 2011).
In recent years, an increasing number of experimental
and modelling studies have been conducted for crops
grown in Asia (Gudhe et al. 2014; Tai et al. 2014;
Emberson et al. 2009; Wang and Mauzerall 2004)
that have increased knowledge of the response toO3 of Asian crop species.
A wide range of experimental methods havebeen used to assess O 3 damage to plants,
including field observation of injury and damage;biomonitoring studies using O3 protectants suchas anti-oxidant chemicals – for example, ethylenediurea (EDU) – (Shamsi 2007; Agrawal et al. 2005),
or using O 3-sensitive versus resistant plants;
controlled fumigation and filtration studies using
open-top chambers (OTCs) (Wahid et al. 1995);
and free air concentration enrichment (FACE)
studies (Kobayashi 2015).

regionally important crops, including peanuts, rice
and wheat (Van and Kim Oanh 2009; Van et al. 2009;
Shamsi, 2007; Ishii et al. 2004; Wahid et al. 1995). A
summary of the experimental study results showing
yield reductions and changes in biomass of major
Asian crops is given in Table 1.1.

These experimental studies have been conducted indifferent parts of the world over the past 40 years,
starting in North America (Heck et al. 1988) andlater Europe (Jäger et al. 1992). In Asia, studies
have been conducted since the 2000s in Japan andother East Asian countries (Jin et al. 2001; Kobayashi
et al. 1995) and have focused on several types of

Research is now starting to focus on developinga better understanding of the mechanisms of O3
damage, both in relation to stomatal O3 uptake
and the consequent impacts on photosynthesis
growth, senescence and yield loss (Emberson
et al. 2018). An important aspect of this impact
mechanism is whether the main damage causeda) Rice (Oryza sativa)b) Maize (Zea mays)c) Onion (Allium cepa)d) Peanut (Arachis hypogaea)e) Soybean (Glycine max)f) Wheat (Triticum aestivum)

Note: Typical injuries caused by O3 include the appearance of yellow or dark brown stipples or flecks and bronzing in
the interveinal region of leaves. These symptoms emerge due to chlorophyll bleaching that causes yellowing in leaves(chlorosis) and localized death of leaf tissues (necrosis), which can expand to larger areas depending on the exposureand sensitivity of the plant.

FIGURE 1.13: SOME TYPICAL O3 INJURIES: A) BRONZING ON LEAVES OF RICE(ORYZA SATIVA); B) INTERVEINAL CHLOROSIS IN LEAVES OF MAIZE (ZEA MAYS);
C) INTERVEINAL CHLOROSIS IN ONION LEAVES (ALLIUM CEPA); D) INTERVEINALCHLOROSIS (WHITE PATCHES) AND NECROSIS (BROWN PATCHES) IN LEAVES OF PEANUT(ARACHIS HYPOGAEA) ALONG WITH SMALLER PLANT BIOMASS; E) BRONZING ON THE LEAF
SURFACE OF SOYBEAN (GLYCINE MAX) AND F) INTERVEINAL CHLOROSISIN LEAVES OF WHEAT (TRITICUM AESTIVUM)
Photos: CEH: rice, maize, onion and soybean; Van and Kim Oanh: peanut; and A. Mishra, Banaras Hindu University: wheat.

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TABLE 1.1: YIELD REDUCTIONS IN MAJOR CROPS IN ASIA AT ELEVATED OZONECONCENTRATIONS IN EXPERIMENTAL STUDIES
Crops

Yield reductions (%) and O3 exposure levels (ppb)
India/South Asia

Maize

7.2–13.8%(+15 and +30 ppb)

Mung bean

9.8–15.4%(+10 ppb)

China/East Asia

PeanutSoutheast Asia

27–49%(32–113 ppb)

Rice

34–38%(35 ppb)

Soybean

12–20%(+10 ppb)

Wheat

11.6–65.6%(60–100 ppb)

8.2–43%(60–200 ppb)

10–48%(32–113 ppb)

8.5–73%(70–200 ppb)

Note: These are mostly OTC studies; (+) indicates the elevated dose above ambient levels. See Annex 1.2 for more details.

by O3 is instantaneous, on the photosynthetic
system, or more long-term through, for example,
earlier and accelerated senescence. Understanding
these mechanisms is important since it would allow
more dynamic modelling than has been performed
to date. This would also allow opportunities toconsider how O3 effects may be influenced byother plant stresses, for example those resulting
from climate change, elevated CO2, soil nutrient
stress or soil water stress.

edited by Izuta (2017). Many of these filtration
studies, in which comparisons are made between
plants grown in clean, filtered air and those grownin ambient air, suggest a significant reductionof tree biomass caused by the current level of O3
concentrations in East Asia, where a 10 per centreduction in whole plant dry mass was observedfor O3-sensitive trees at exposures above 40 parts
per million over the growing season of six months(Kohno et al. 2005).

In addition to the quantitative reduction in crop yield,
ambient and elevated O3 can affect the quality ofcrops (Rai et al. 2016). Yields of leafy crops arenotably decreased due to visible damage to theleaves, thus reducing the crops’ economic value(Ainsworth 2016). With respect to the quality ofgrain crops, elevated O3 decreases starch, protein
and nutrient contents in wheat and rice grains (Box1.4) (Rai et al. 2010; Rai et al. 2007).

Reduction of biomass in tree species can directly
influence the annual carbon cycle. The O3-induced
reduction in the total annual carbon absorption/
assimilation of three conifer tree species in Japanwas estimated to be 0.8 per cent (Watanabe et al.
2010). In Beijing, China, visible injuries due to O3
were observed (Feng et al. 2014) as field evidenceof O3 pollution for 28 species of crops, nativeplants and ornamental plants. These observations
were found to be more frequent in rural areas andmountainous regions downwind from the city, andless frequent in city gardens. The O3 monitoringdata from remote areas including mountains andEffects of O3 on Asian tree species have also beenstudied intensively in Japan and China, and mostof these studies have been summarized in a book38

BOX 1.4: EFFECTS OF GROUND-LEVEL OZONE ON WHEAT AND RICEThe OTC experiment results from Zheng et al. (2013) revealed an increase in a range of key
nutrients including calcium (Ca), copper (Cu), nitrogen (N), potassium (K), sulphur (S) and zinc (Zn)in rice exposed to O3. The concentrations of protein and amino acids such as lysine (C6H14N2O2)
in winter wheat and rice were also increased, while the concentration of amylose ((C6H10O5)n)decreased. However, because of the more significant reduction of the grain yield in both winterwheat and rice, the absolute total amount of nutrients produced in the crop was reduced byelevated O3 (Zheng et al. 2013). For rice, elevated O3 significantly increased grain chalkiness andthe concentrations of essential nutrients, which was particularly significant for Zn and Cu.The
O3-induced changes in starch pasting properties, for example a decrease in (C 6H10O5)nconcentration, indicated a deterioration in the cooking and eating quality (Wang et al. 2014).
The contents of protein, total amino acids (TAA), total essential (TEAA) and non-essential aminoacids (TNEAA) in rice grain increased with elevated O3 concentration (Zhou et al. 2015; Wang et al.
2014). A similar significant response to O3 was observed for concentrations of the seven essentialand eight non-essential amino acids. In contrast, elevated O3 caused a small but significant
decrease in the percentage of TEAA within TAA (Zhou et al. 2015).

large expanses of forests are, however, still limited
and this has so far prevented comprehensive
studies of O3 effects on forests.
In many Asian countries, a lack of monitoring data
describing O3 concentrations, especially in rural andremote areas, is the first obstacle to a comprehensive
assessment of the impact of O3 on crop yield losses.
Regional-scale risk assessments of O3 damage
therefore rely mostly on modelling methods thatuse estimates of O3 concentration derived fromglobal or regional atmospheric chemistry transportmodels (CTMs). These concentration fields canthen be combined with data describing crop
distribution and production along with empiricallyderived statistical relationships between crop yieldand O3 concentration to estimate crop production
losses. Several concentration-response metrics(AOT40, M7/M12 and W126, for example) havebeen used to quantify crop yield loss due to O3
concentrations (Danh et al. 2016; Gudhe et al. 2014;
Avnery et al. 2011; van Dingenen et al. 2009; Wang
and Mauzerall 2004; Aunan et al. 2000). Based on
simulated O3 levels, the rice yield loss in Thailand
was estimated at 0.84 per cent for the second crop
growing in high O3 months, November–April in
2003–2004 with the maximum loss of 2.6 per centoccurring in provinces surrounding Bangkok(Nghiem 2007).

More recently, flux-response metrics have beendeveloped that account for the influence ofenvironmental conditions limiting stomatal O 3
uptake. Tang et al. (2013) used such a metric,
derived from experiments conducted at a FACE
site in China, and found relative yield losses forwheat for the whole of China to be in the range
of 6.4–14.9 per cent. Danh et al. (2016) used theflux-response approach and estimated the rice
yield loss in the southeastern part of Viet Nam
in 2010 to be in the range of 0.51–5.7 per cent,varying with crop cycle. Other approaches include
the development and application of statisticalregression models that can relate pollutant
concentrations to actual yields that occur over anumber of years across different regions. Burneyand Ramanathan (2014) derived such a statisticalregression model from relationships between
yield from 1980–2010 with O3 and BC pollution
estimated from emission data. They showed thatthe yield loss of wheat due to these pollutants
was 18.9 per cent for the whole of India in 2010.
Table 1.2 presents the range of crop yield losses
estimated using AOT40 and M7 metrics based ona recent review by Ainsworth. (2016) and several
other studies for rice crops.

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TABLE 1.2: ESTIMATED YIELD LOSSES USING MODELLING STUDIES
World
%

North
America %European
Union %

China/East
Asia %

India/South Asia,
Southeast Asia %AOT40

2.2–2.4

2.0–2.2

3.1–3.5

3.8–4.7

2.0–3.4%

M7

4.1–5.5

3.6

5.1–7.9

7.1–8.0

4.0–8.0%

Maize

Rice
1.6–4.0a, 2.1e

AOT40
M7

1.1–1.5c,
3–5d

0.35–0.45a,
0.84b

Soybean
AOT40

5.4–8.5

7.1–12.0

20.5–23.9

11.4–20.9

3.1–4.7, 2.7e

M7

13.9–15.6

16.9–17.7

27.3–27.4

20.8–24.7

13.2–19.1

AOT40

12.3–15.4

4.1–11.0

4.1–12.1

16.3–19.0

26.7–27.6, 5eM7

3.9–7.3

2.6–4.4

3.3–4.6

3.3–9.8

8.2–13.2

Wheat

Note: a Danh et al. 2016 (southeastern part of Vietnam); b Nghiem 2007 (Thailand); c Aunan et al. 2000 (China); d Wang et al. 2014
(China); e Ghude et al. 2014 (India). Other data are based on Ainsworth (2016).

Modelling studies have also been conducted
to investigate the impact of future projected O3
concentrations on crops in Asia. Increases in
the future emissions of O3 precursors in China
would lead to increases in surface O3 which could
cause substantial reductions in crop production in
the country (Aunan et al. 2000). Given projected
increases in O3 concentrations in East Asia, it isestimated that grain yield loss would increaseby 2–16 per cent for maize, rice and wheat, and
28–35 per cent for soybeans in 2020 compared
to 1990 (Wang and Mauzerall 2004).
1.4.2.2 Factors affecting the extent of ozone impacts
High concentrations of tropospheric O3 during crop
growing seasons lead to substantial reductions in40

the yields of different crops (Rai et al. 2016).
A study focused on Punjab and Haryana, India’s
major agricultural regions, indicated yield losses
due to O3 in the range of 27–41 per cent for wheat,
21–26 per cent for rice and 3–5 per cent for maize
in 2012–2014 (Sinha et al. 2015). Such studies
show that higher yield losses can occur in heavily
polluted regions for sensitive varieties, especiallywhen they also suffer from such additional stresses
as rising temperatures during the growing season.
The timing of the crop growing season can also
be important. There are, for example, two or threerice crop cycles a year in many parts of Southeast
Asia, and the crops grown in the months with highO3 levels are most susceptible to both current
and future increasing O 3 levels in countries
such as Thailand (Nghiem 2007) and Viet Nam

(Danh et al. 2016). Lal et al. (2017) modelled
estimates for the losses of wheat and rice yields
using surface O3 observations from a group of 17
sites, for the first time, covering different parts ofIndia, which showed a total all-India annual lossof 4.0–14.2 million tonnes, 4.2–15.0 per cent of
the total wheat crop, and 0.3–6.7 million tonnes ofrice, 0.3–6.3 per cent of the total crop. The lower
losses of rice were mainly due to lower surface O3
levels during the cropping season after the Indiansummer monsoon.
The sensitivity of plants to changes in O 3
concentrations due to climate conditions makes
the projection of the effects of air pollution onplants in future climate change scenarios complex.
Drought stress and increasing temperatures,for example, will reduce stomatal conductanceand therefore the uptake of O3 to the internal
cellular sites where damage occurs. The limited
number of studies that have been carried out oncrops to explore drought-O3 interactions (Fengand Kobayashi 2009) have found that the direct
damaging effect of drought stress on yield often
outweighs the positive impact of O3 exclusion(Fangmeier et al. 1994).
The CO2 fertilization effect is also considered likely
to result in less O3 damage since the stomates,
the leaf pores that allow gas exchange, will tend
to close to conserve water whilst allowing thesame levels of CO2 uptake for photosynthesis(Feng et al. 2009). Similar responses will likely
occur in forest ecosystems (Fleisher et al. 2005).
Beside the interactions between climate variables
and O3 uptake, a plant already stressed by, forexample, drought or heat, may be more sensitive
to an internal O3 dose. To fully understand theseinteractions further empirical research is required.
Asia is the world’s most populous continent withlarge emissions from key economic sectors(Chapter 2). High emissions of O3 precursors(Figure 2, Introduction) coupled with favourable
meteorological conditions (Permadi and Kim
Oanh 2008; Zhang and Kim Oanh 2002) enhancetropospheric O 3 formation and build-up. The
mixed land-use pattern commonly observed in
Asian developing countries with agricultural land
adjacent to urban areas increases the exposure of

agricultural crops to air pollutants of urban origin,especially to O3 that is normally found at higher
concentrations downwind of large urban centres(Nghiem and Kim Oanh 2009). The declines in crop
yield due to air pollution, and O3 in particular, resultin the need for additional cropland to meet fooddemand and hence cause further land-use change.
Chuwah et al. (2015) estimated that for 2005, thecrop production losses for maize and rice in Asia
were up to 5 tonnes per square kilometre (km2)
in some parts of China and India. If air pollution
policies are not strengthened, crop production
losses in 2050 might go up to 10 tonnes/km2.
The study further projected that if air pollution
mitigation were not implemented, crop losses due
to O3 would require that to meet demand in 2050,
the global crop area would need to be increasedby 2.5 per cent, approximately 1.3 million km2.
This translates into an 8.9 per cent increase inrequirements for crop areas across Asia, which
will put additional pressure on already scarceland resources.
1.4.3 Acidification and eutrophication effects of
air pollution at local and regional scales
Air pollutants containing N and S can have a variety ofeffects related to acidification and eutrophication of
the environment. Depending on proximity to emission
sources, sensitive ecosystems and water catchments
can receive a mixture of wet and dry depositionsof S and reduced and oxidized N compounds. For
example, dry deposition close to point sources of SO2
emissions near power stations and NH3 depositions
near intensive animal-rearing facilities can cause
local impacts. Wet depositions containing sulphate,nitrate and ammonium can cause acidificationand eutrophication impacts at a regional scale.
Asia is now the global hotspot of N and S depositions(Figure 1.14); since the early 2000s, the global
maximum depositions of both N and S are foundin East Asia, including regions in eastern China
and the Republic of Korea, Bangladesh, India,
Japan, the Democratic People’s Republic of Korea,
Laos, Myanmar, Thailand and parts of Pakistan(Vet et al. 2014).

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41

FIGURE 1.14: 2001 ENSEMBLE-MEAN PATTERNS OF NITROGEN WET AND DRY DEPOSITIONOF OXIDIZED (E.G. NITRATES AND NOX) AND REDUCED (E.G. AMMONIUM AND AMMONIA)
FORMS (ABOVE) AND SULPHUR WET AND DRY DEPOSITION(E.G. SULPHATE AND SULPHUR DIOXIDE) (BELOW)
Source: Vet et al. 201442

Acid deposition can have both direct and indirect
effects on ecosystems. The damage to crops is often
regarded as the most direct impact caused by low-pH(acidity) precipitation and/or high concentrationsof ambient SO2 or NH3. Evidence from research in
China has shown that such crops as barley, spinach
and wheat are susceptible to visible damage from
acidic rainfall at pH 3 and a range of crops show
yield losses at pH 4–5, whereas crops such as riceand peanut only show yield loss at rainfall pH of lessthan 2.8 (Zhang et al. 1998). Since the 1980s, forest
decline has been observed in east and southwest
China, mainly caused by direct damage on leaves
due to SO2 in the air and acidic precipitation (Ma1991; Yu et al. 1990). Although direct above-ground
phytotoxicity of SO2 and acid precipitation on leaves
and needles may contribute to the death of trees,
the indirect effects of soil acidification resulting inaluminium (Al) activation and nutrient deficiency inthe soil may be the most important long-term causeof forest decline. A recent review of the current stateof knowledge regarding acid deposition and its
environmental effects across Asia (Duan et al. 2016)shows that the characteristics of soil and surface
water acidification in Asia are different from thoseexperienced earlier in Europe and North America.
The net and potential acidity of rain water are
affected by other factors including the abundanceof atmospheric dust rich in calcium carbonate(CaCO3) in India which has been reported toincrease the pH of rain water (Kulshrestha 2013).
Nitrogen deposition can have beneficial effects oncrop and forestry yields as a free source of fertilizer
and can also act as a carbon sink in temperate
and tropical forests in Asia, with phosphorus (P)deposition being important in determining how
much N deposition can stimulate growth (Wanget al. 2017; Du et al. 2016). Although N deposition
can improve soil N availability and result inincreased photosynthetic capacity and stimulationof plant growth in N-limited ecosystems (Bai etal. 2010; Xia et al. 2009; Fan et al. 2007), excess
N input can also lead to restricted plant growthor even damage to plants through changes insoil N status (Fang et al. 2009; Lu et al. 2009; Xuet al. 2009), nutrient imbalance (Yang et al. 2009)or a reduction in net photosynthesis (Guo et al.
2014; Mo et al. 2008b). Examination of six forests
in southern China and Japan indicated that, in

addition to leaching, denitrification losses of NO3grew significantly with increasing N deposition,
which in turn increased soil N2O emissions (Fanget al. 2015). Nitrogen emissions to the atmospherecan also be exacerbated by the use of organic andinorganic fertilizers and can lead to problems ofnitrate leaching and the contamination of groundand surface waters in Asia, as has occurred in
China (Gao et al. 2016b), India (Abrol et al. 2017)
and Japan (Nakahara et al. 2010). Riverine andatmospheric N inputs also give rise to toxic algal
blooms in Asia (Abrol et al. 2017; Tian et al. 2017).
Biodiversity could also be significantly affectedby N deposition, with the level depending on
soil N status, vegetation composition, dose andduration of N addition, and the N requirements ofdifferent species (Bai et al. 2010; Bobbink et al.
2010). Excessive N deposition normally reduces
biodiversity, including forest understory species(Lu et al. 2011, 2010, 2008), grasses and forbs(Bai et al. 2010) and soil fauna (Xu et al. 2006).
1.4.4 Impacts of particulate matter on plants andecosystems
1.4.4.1 Effects of particulate matter on radiation
Particulate matter and atmospheric aerosols
have effects on solar radiation that can have both
positive and negative impacts on vegetation.
On the positive side, anthropogenic aerosols in
the atmosphere have been associated with anincrease in the diffuse fraction of incoming solar
radiation that may have a positive effect on crop
photosynthesis and yield (Wild 2012; Steiner et al.
2005). Early studies suggested that an increasein diffuse light may increase photosynthesis,
because diffuse light is more able to penetrate
the canopy and can promote overall total canopy
photosynthesis (Gu et al. 2002). This may help toalleviate climate change as the carbon sequesteredin plant biomass is increased, altering the global
carbon cycle. Mercado et al. (2009) estimated thatvariations in diffuse fraction, associated largely with
global dimming, enhanced the land carbon sink byapproximately one quarter between 1960 and 1999.
On the negative side, the amount of radiation
reaching the Earth’s surface is an important driverof ecosystem and agricultural productivity and

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

43

affects light-limited photosynthesis and both
surface air and leaf temperatures. The compositionof the atmosphere can reduce incoming radiation
through the presence of aerosols and clouds(Cheng et al. 2015; Gu et al. 2003; Roderick et al.
2001); this is known as the dimming effect. Thischange in solar radiation has the potential toreduce CO2 uptake in both natural vegetation andagricultural systems, as well as alter the balanceof sensible and latent heat in the Earth’s energybalance (Mercado et al. 2009; Ramanathan 2006).
Depending on the amount of scattering or extinction
by clouds and aerosols, this simultaneous decrease
in total radiation and increase in diffuse radiation
may lead to a trade-off between the efficiency andmagnitude of radiation available for photosynthesis(Oliphant et al. 2011; Mercado et al. 2009). Tie et al.
(2016) estimated the reduction in yields in several
regions of China caused by the reduction in radiation
alone to be 2 per cent for the total rice crop and 8 percent for wheat. When, however, the increase in diffuse
radiation was considered, the yield reductions werelower, at 1 per cent and 4.5 per cent respectively.
Ground-based observational studies have also
quantified the response of ecosystems to diffuse
light. Several showed that carbon uptake would
rise with the increase in atmospheric aerosol load
which provided more diffuse radiation (Min 2005;
Gu et al. 2003, 2002). Several of these groundbased studies suggest that there is a limitation tothis response; for example, Knohl and Baldocchi(2008) show that photosynthesis and transpiration
increase with increasing light up to a diffuse
fraction of 0.45, after which the net benefit ofdiffuse light decreases due to the overall reduction
in light levels. A comprehensive review of this
topic is provided in Kanniah et al. (2012), and themagnitude of this effect has been tested using
ground-based data sets and atmospheric models,
but further studies are required under the different
conditions found across the Asia and Pacific region.
1.4.4.2 Possible effects of particulate deposition toplantsHigh levels of total suspended particles arecommonly observed in Asian developing countries.
These large particles can easily deposit on trees
and crops, and can subsequently alter leaf surface

44

conditions, such as degradation/erosion ofleaf-surface (epicuticular) wax and stomata
occluded with particles. Stomata occluded byparticulate matter have been observed on European
tree species (Crossley and Fowler 1986; Grill and
Golob 1983; Smith 1977) and also for Japanesecedar (Cryptomeria japonica) (Takamatsu et al. 2001;
Sase et al. 1998). Accelerated water loss due to themalfunction of stomata and dry meteorologicalconditions in urban areas appeared to be a significant
factor causing the decline of Japanese cedar
trees observed in Kanto Plain near Tokyo, Japan(Takamatsu et al. 2001; Sase et al. 1998). Moreover,deposition of dark coloured particulate matter, suchas BC, caused a reduction of the photosynthetic ratein crops due to a shading effect (Hirano et al. 1995).
Izuta et al. (2014), using the short-term exposure
test, reported that the net photosynthetic rates inJapanese tree species were reduced by 10 per centdue to relatively large amounts, 3.2–39.0 milligrams
per square metre (mg/m2), of BC deposition to theleaves. In Japan, according to field observational
studies in Hokkaido (Fukazawa et al. 2012) and Tokyo(Hara et al. 2014), the amounts of BC deposited onleaf surfaces were 9−14 mg/m2 for larch and 10–15
mg/m2 for oak, which could induce a 10 per centreduction in the net photosynthetic rate.
Although the relevant studies are relatively limited,
reduction of crop yields due to particulate matter
deposition has also been suggested in the Yangtze
delta region of China (Bergin et al. 2001). Plant
leaves along big dusty roads in developing Asia
are often covered with blackish dust that would
occlude stomata and affect plant growth. Acidic
components, sulphate and nitrate, and othercomponents of the deposit dust can directly
damage the leaves (Mishra and Kulshrestha 2017;
Gupta et al. 2016). Therefore, the particulate matter
deposition to terrestrial ecosystems should not be
neglected as a possible stressor in Asia and thePacific. Further studies are required to determine
the magnitude of the effects.
1.4.5 Impacts of air pollution on the carbon cycle
There is still only a limited number of regional
studies on the impacts of air pollutants on the
carbon cycle. These impacts have been assessedby several mechanisms (UNEP/WMO 2011) bywhich air pollutants affect plant photosynthesis

rates and thus CO2 uptake. As previously described,
O3 damage to plants, aerosol dimming and aciddeposition on plants and soils can affect the carbon
cycle. Tropospheric O3 can damage plants andreduce primary productivity while the increase in CO2
concentrations is thought to stimulate plant primary
productivity, referred to as the CO2 fertilization effect.
The interactive effects of O3 and atmospheric
CO2 on plants have received much attention,although understanding is far from complete.
Sanderson et al. (2007) simulated the impact ofincreasing levels of CO2 on stomatal conductanceand surface O3 levels using a global generalcirculation model. They showed that a doubled
level of CO2 would increase surface O3 levels by
2–8 ppb in all four seasons as increased CO2
reduces stomatal conductance, which subsequently
decreases O3 ﬂux into plants (Ainsworth and Rogers
2007). Reduced stomatal conductance that occurs in
response to elevated CO2 may enhance plant wateruse efﬁciency, which could help to partly alleviate theeffects of reduced rainfall. Increased water stress ina warmer climate may also decrease sensitivity to O3
through reduced uptake. These potential feedbacks
are complicated in combination with the increased
temperature, drought and plant transpiration that
affect the water balance (Ainsworth et al. 2012).
When O3 concentrations are high enough to reduce
photosynthesis, less CO2 is absorbed by the leaves ofvegetation (Mills et al. 2013), which in turn facilitates
the accumulation of CO2 in the atmosphere. Sitch etal. (2007) used a global land carbon-cycle model toquantify the impact of future O3 levels on the landcarbon sink and found a significant suppression
because an increase in O3 concentrations reduces
plant productivity. Watanabe et al. (2010) assessed
the risk of O3 reducing C absorption by tree species
in Japan. Taking account of spatial distribution of
accumulated O3 exposure above a threshold of
60 ppb (AOT60), habitats of the Japanese cedar(Cryptomeria japonica), Japanese pine (Pinus
densiflora) and Japanese larch (Larix kaempferi) andtheir annual carbon absorption and sensitivities to
O3 exposure, the O3-induced reduction in the annual
C absorption in Japan was estimated and mapped.
The results showed that the total O3-induced
reduction of annual C absorption by three species
was 0.8 per cent.

1.4.6 Conclusions
Measures to improve air quality will have multiple
benefits for the adverse effects on crop yields andecosystem services as detailed in this section.

• Ozone, particulate matter and related
		 pollutants, including those involved in		 long-range transport (SO2, NOx, NH3, CH4
		 and CO), can directly or indirectly affect		 ecosystems adversely in Asia and the Pacific,
		 which can influence crop production and		 important ecosystem services.

• Recent estimates from experimental studies
		 in Asia for important crops, such as maize,		 mung bean, peanut, rice, soybean and wheat,		 show crop-yield losses due to exposure to		 ground-level O3 at the common levels found		 in the region that can range from 5 per cent		 to more than 30 per cent depending on the		 crop and ambient conditions – taking O3
		 exposure of 50 ppb as the reference.

• Particulate matter and its precursors,		 including secondary particulate matter that can		 be transported over large distances – sulphate,		 nitrate and ammonium particles – can have		 adverse effects on ecosystems and their		 biodiversity in Asia, causing, for example,
		 eutrophication and acidification that can		 affect crop production and damage surface
		 water, soil quality and biodiversity.

• The influence of atmospheric aerosols or		 particulate matter, including BC particles,		 on the quality of sunlight reaching vegetation
		 can have positive and negative impacts on
		 plant growth and productivity. Particles
		 deposited on trees and crops can alter leaf
		 surface conditions and block stomata,		 affecting the plant growth. Further study is		 required to determine the net impacts of		 these effects and also of air pollution on the		 carbon cycle.

• While more research will help to quantify
		 effects, action is justified and urgently needed		 to reduce O3 concentrations and the deposition
		 of substances causing acidification and		eutrophication.

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

45

• Global photochemical models project		 that parts of the region will experience further
		 significant increases in O3 concentrations
		 by 2030. High emissions of substances that		 contribute to the formation of O3 coupled		 with favourable meteorological conditions
		 enhance O3 formation. The mixed land-use
		 pattern commonly observed in developing		 countries in Asia and the Pacific, where		 agricultural land is adjacent to urban areas,		 increases the exposure of crops to O3.

1.5 SOCIO-ECONOMIC DEVELOPMENT
PATHWAYS, AIR QUALITY ANDSUSTAINABLE DEVELOPMENT GOALSIN THE ASIA AND THE PACIFIC
1.5.1. Socio-economic development pathways
and air quality in Asia and the PacificFossil fuels have provided people with convenienceand mobility for several generations, but they havealso created serious environmental problems
in their production and consumption processes
through the emission of air pollutants as well as
greenhouse gases. Air pollution resulting fromfossil fuel consumption has induced adverse
effects on ecosystems, the ambient environment
and public health as described in previous sections.
Many countries have sought to balanceenvironmental and public health concerns with theireconomic growth. The Asia and Pacific region’s total
population grew at an annual rate of 1.21 per centbetween 2000 and 2015 and by 2016 was home tomore than 4.5 billion people, accounting for nearly
60 per cent of the world’s population (UNESCAP
2016a). In 2015, the region’s five most populous
economies were China, 1.4 billion; India, 1.3 billion;
Indonesia, 258 million; Pakistan, 189 million and
Bangladesh, 161 million. Many countries in theregion are still in the early stages of economic
development, with policy makers facing a numberof economic and environmental challenges, andtrade-offs. Nonetheless, air pollution is progressing
up the list of policy priorities everywhere, as reflectedin the United Nations Environment Assembly
resolutions on air quality (http://web.unep.org/
environmentassembly/).

46

The combination of high population density, anenergy-intensive economic structure, and highdependence on coal has led to serious air pollution
problems. Many Asian cities have experienced
severe air pollution, especially with PM2.5. Only
two of 230 Asian cities complied with the WHO
Guideline in 2008 (CAI-Asia 2010), while averageannual PM2.5 levels in Asia have continued to
exceed the annual WHO Guideline over thelast two decades. This section examines how
socio-economic development is coupled with,or decoupled from, air quality in Asian countries(Figures 1.15 and 1.16). A majority of low-income
countries in this region are exposed to high PM2.5
concentrations, except for Pacific island countries.
As shown in Figure 1.15, the PM2.5 concentration
stabilizes with economic growth, assumingthat developing economies follow the previous
pathways of other countries. Policy interventions
have helped to break the historic link between
economic growth and pollution and, with thepolicies that are already in place, countries can
expect economic growth with no increase in air
pollution. Examples of earlier decoupling of PM2.5
concentrations and economic development are
China, Indonesia, Pakistan, Sri Lanka, Thailand andViet Nam (Figure 1.16).
Coal combustion is another major factor affecting air
pollution in developing countries. A high proportion ofcoal in electricity generation contributes to high PM2.5
concentrations in the region (Figures 1.17 and 1.18).
Here again, however, many of the region’s countries
show earlier decoupling. In Indonesia, Malaysia,
Philippines and Viet Nam, PM2.5 concentrations
have stabilized despite the increasing portion ofcoal in electricity generation. Australia has kept
emissions low despite a high proportion of energy
generation from coal and China recently introduced
ultra-low emission control technologies for power
plants as well.
Carbon dioxide emissions have a strong correlation
with GDP (Figures 1.19 and 1.20). As shown earlier,although low- and middle-income countries improve
air quality once a certain income level has beenreached, CO2 emissions continue to grow. Economic
development often comes with high energy
consumption. In most middle-income countries of

PM2.5 mean annual exposure

High income
Middle income
Low income

GDP per person (purchasing power parity, current international $)AUS - Australia BGD - Bangladesh BRN - Brunei BTN - Bhutan CHN - China FJI - Fiji IDN - Indonesia IND - India JPN - Japan KHM - Cambodia
KIR - Kiribati KOR - Republic of Korea LAO - Lao PDR LKA - Sri Lanka MHL - Marshall Isalands MMR - Myanmar MNG - Mongolia MYS - Malaysia
NPL - Nepal NZL - New Zealand OECD - Organization for Economic Co-operation and Development including 36 countries PAK - Pakistan
PHL - Philippines PNG - Papua New Guinea SGP - Singapore SLB - Solomon Islands THA - Thailand VNM - Viet Nam VUT - Vanuatu WSM - Samoa
Note: World Bank’s country code

Note: PM2.5 mean is annual weighted population exposure from the GBD 2013 study (Brauer et al. 2016). Exposure
is calculated by weighting mean annual concentrations of PM2.5 by population in both urban and rural areas.

FIGURE 1.15: PM2.5 CONCENTRATIONS AND GDP PER PERSONBY COUNTRY IN ASIA AND THE PACIFIC
Source: World Bank 2014a, 2014b

High income
Middle income
Low income
2005

2014

PM2.5 mean annual exposure

1995

GDP per person (purchasing power parity, current international $)AUS - Australia BGD - Bangladesh BRN - Brunei BTN - Bhutan CHN - China FJI - Fiji IDN - Indonesia IND - India JPN - Japan KHM - Cambodia
KIR - Kiribati KOR - Republic of Korea LAO - Lao PDR LKA - Sri Lanka MHL - Marshall Isalands MMR - Myanmar MNG - Mongolia MYS - Malaysia
NPL - Nepal NZL - New Zealand OECD - Organization for Economic Co-operation and Development including 36 countries PAK - Pakistan
PHL - Philippines PNG - Papua New Guinea SGP - Singapore SLB - Solomon Islands THA - Thailand VNM - Viet Nam VUT - Vanuatu WSM - Samoa
Note: World Bank’s country code

Note: PM2.5 mean is annual weighted population exposure from the GBD 2013 study (Brauer et al. 2016). Exposure
is calculated by weighting mean annual concentrations of PM2.5 by population in both urban and rural areas.

FIGURE 1.16: PATHWAYS OF PM2.5 CONCENTRATION AND ECONOMIC DEVELOPMENTBY COUNTRY IN ASIA AND THE PACIFIC
Source: World Bank 2014a, 2014b

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

47

PM2.5 mean annual exposure

High income
Middle income
Low income

Electricity generation from coal (% of total)
AUS - Australia BGD - Bangladesh BRN - Brunei BTN - Bhutan CHN - China FJI - Fiji IDN - Indonesia IND - India JPN - Japan KHM - Cambodia
KIR - Kiribati KOR - Republic of Korea LAO - Lao PDR LKA - Sri Lanka MHL - Marshall Isalands MMR - Myanmar MNG - Mongolia MYS - Malaysia
NPL - Nepal NZL - New Zealand OECD - Organization for Economic Co-operation and Development including 36 countries PAK - Pakistan
PHL - Philippines PNG - Papua New Guinea SGP - Singapore SLB - Solomon Islands THA - Thailand VNM - Viet Nam VUT - Vanuatu WSM - Samoa
Note: World Bank’s country code

Note: PM2.5 mean is annual weighted population exposure from the GBD 2013 study (Brauer et al. 2016). Exposure
is calculated by weighting mean annual concentrations of PM2.5 by population in both urban and rural areas.

FIGURE 1.17: PM2.5 CONCENTRATIONS AND THE PERCENTAGE OF ELECTRICITY
GENERATED FROM COAL BY COUNTRY IN ASIA AND THE PACIFIC
Source: World Bank 2014a, 2014b

High income
Middle income
Low income
2005

2014

PM2.5 mean annual exposure

1995

Electricity generation from coal (% of total)
AUS - Australia BGD - Bangladesh CHN - China FJI - Fiji IDN - Indonesia IND - India JPN - Japan KOR - Republic of Korea LKA - Sri Lanka
MMR - Myanmar MNG - Mongolia MYS - Malaysia OECD - Organization for Economic Co-operation and Development including 36 countries
PAK - Pakistan PHL - Philippines SGP - Singapore THA - Thailand VNM - Viet Nam
Note: World Bank’s country code

Note: PM2.5 mean is annual weighted population exposure from the GBD 2013 study (Brauer et al. 2016). Exposure
is calculated by weighting mean annual concentrations of PM2.5 by population in both urban and rural areas.

FIGURE 1.18: PATHWAYS OF PM2.5 CONCENTRATION AND THE PERCENTAGE OF
ELECTRICITY GENERATION FROM COAL BY COUNTRY IN ASIA AND THE PACIFIC
Source: World Bank 2014a, 2014b48

Asia and the Pacific, CO2 emissions have increased
as countries become wealthier. Thus, many have an
undesirably high potential for further increases in CO2emissions, and it is likely that many of the region’s
rapidly growing economies will emit more PM2.5
and CO2 in the near future. However, high-income
countries with low carbon-emission policies, such as
Australia, Japan and New Zealand, show a decouplingof CO2 emissions from GDP per person. In addition,some countries in the region have already shown
earlier decoupling of PM2.5 concentrations andcoal consumption with economic development.
Therefore, informed environmental policy
decisions, along with a strong national mandate
for sustainable growth, such as a continuing andincreasing attention to clean energy, can reduce
both air pollutant and CO2 emissions. By taking
these sustainable socio-economic development
pathways, including clean fuel use and urban
planning, countries in Asia and the Pacific may beable to continue on their road to developed-nation
status and still be able to manage their local air
quality as well as contribute to climate change
mitigation by decreasing greenhouse gas emissions.

1.5.2 Air quality and sustainable cities
As mentioned in the previous section, the Asia
and Pacific region was home to about 4.5 billion
people in 2016. The extent of urbanization acrosssub-regions varies, with rates ranging from ashigh as 85 per cent in the Pacific to 34 per centin Southeast Asia (Figure 1.21) (UNESCAP 2013),
and by 2050 it is expected that two-thirds of the
population in Asia and the Pacific will live in urban
areas (UNESCAP 2014). Contributions to urban
growth are varied, and sub-regional analysis tends
to hide country-to-country realities. Nevertheless,general trends suggest high rates of urbanization
across Asia and the Pacific. Pacific growth rates
have limited impact due to their inherently small
populations (UN-Habitat and UNESCAP 2015).
The region is also home to seven of the 10 mostpopulous cities in the world (Wharton 2012) –Beijing, Delhi, Dhaka, Kolkata, Mumbai, Shanghai
and Tokyo – and is projected to have 21 of 37
global megacities, those with populations of morethan 10 million people, by 2025 (Figure 1.22) (ADB

TonnesHigh income
Middle income
Low income
2005

2014

CO2 emissions per person

1995

GDP per person (purchasing power parity, current international $)MHL – Marshall Islands VNM – Viet Nam IDN - Indonesia IND – India FJI - Fiji BTN - Bhutan WSM – Samua PHL – Philippines
PAK – Pakistan LKA – Sri Lanka PNG – Papua New Guinea VUT – Vanuatu KIR – Kiribati BGD – Bangladesh KHM – Cambodia
MMR – Myanmar LAO – Lao PDR SLB – Solomon Islands NPL – Nepal

FIGURE 1.19: PATHWAYS OF CO2 EMISSIONS AND ECONOMIC DEVELOPMENTBY COUNTRY IN ASIA AND THE PACIFIC
Source: World Bank 2014b

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

49

High income
Middle income
Low income
2005

2014

PM2.5 mean annual exposure

1995

CO2 intensity (kg/kg of oil equivalent energy use)
AUS - Australia BGD - Bangladesh BRN - Brunei CHN - China IDN - Indonesia IND - India JPN - Japan KHM - Cambodia KOR - Republic ofKorea LKA - Sri Lanka MMR - Myanmar MNG - Mongolia MYS - Malaysia NPL - Nepal NZL - New Zealand OECD - Organization for Economic
Co-operation and Development including 36 countries PAK - Pakistan PHL - Philippines SGP - Singapore THA - Thailand VNM - Viet Nam
Note: World Bank’s country code

Note: PM2.5 mean is annual weighted population exposure from the GBD 2013 study (Brauer et al. 2016). Exposure
is calculated by weighting mean annual concentrations of PM2.5 by population in both urban and rural areas.

FIGURE 1.20: PATHWAYS OF PM2.5 CONCENTRATION AND CO2 INTENSITYBY COUNTRY IN ASIA AND THE PACIFIC
Source: World Bank 2014a, 2014b

80
70
Pacific

Urban population (%)

60

North and Central
Asia
East and Northeast
Asia
Southeast Asia

50
40
30

ESCAP region

20

South andSouth West Asia

10
0
1990

2000

2010

2020

Note: the geographic sub-regions shown here vary from those used in the present study.

FIGURE 1.21: URBANIZATION IN ASIA AND THE PACIFIC, 1990–2020
Source: UNESCAP 201350

2015). These cities are hubs of socio-economic andpolitical activity in the region and serve as major
drivers of the global economy (UNESCAP 2016a).
Overall, the Asia and Pacific urban population
provides 80 per cent of the region’s GDP despite
having about 40 per cent of the population (ADB2012). Existing cities are also rapidly expanding toform mega-cities, urban corridors and city-regions.
These urban configurations result in faster economic
and demographic growth than that of the countries
in which they are located (UN-Habitat 2016).
1.5.2.1 Urbanization as a key driver of air pollution
and greenhouse gas emissions
Much of the growth and economic productivity ofcities is closely tied to energy demand. Given theregion’s rapid expansion, the Asia Pacific Energy
Research Centre expects energy demand toincrease by 32 per cent by 2040, driven by theindustrial, transport and residential sectors in
relatively equal parts (APERC 2016). This has
significant implications for air quality and greenhousegas emissions given that the region’s energy systems

are largely based on fossil fuels (UNESCAP 2016b),
particularly coal and natural gas (US EIA 2016).
Looking at transport, increased car ownership isstrong in China, India and Southeast Asia. Road
transport presents other challenges such ascongestion and concentrated urban emissions
in heavily populated areas, as well as significant
contributions to PM2.5 and NOx levels due to thereliance on diesel fuel (IEA 2016).
Most cities are energy intensive, and Asian ones are
no exception (UN-Habitat 2016). The IEA estimatesthat globally 85 per cent of particulate matter anda majority of sulphur oxides (SOx) and NOx are
due to ‘unregulated, poorly regulated or inefficientfuel combustion’ resulting from the energy-use
patterns arising from poverty, solid fuel use
and urbanization (IEA 2016). Given the inherent
high-energy use of cities and their reliance on
fossil fuels, the majority of the people living incities are exposed to unhealthy levels of air
pollution every day. For Asia, seven in every 10
cities suffer from poor air quality. Most of these

Percentage urban
> 80
60–80
40–60
20–40
< 20
Below it should be
Megacities > 10 million
Large cities 5–10 million
Medium-sized cities 1–5 million
Cities of 500,000–1 million

FIGURE 1.22: LOCATION AND SIZE OF URBAN AGGLOMERATIONS,AND COUNTRIES’ URBAN POPULATION
Source: Enjie et al. 2015 (Figure is reproduced from United Nations Department of Economic and Social Affairs Population Division,
2014: https://esa.un.org/unpd/wup/Publications/Files/WUP2014-Report.pdf.)

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

51

cities exceed both the interim targets and theannual PM10 and PM2.5 guideline values set by
the WHO (Figure 1.23).
1.5.2.2 Air quality impacts on economies
Air quality is one of the main determinants ofenvironmental quality in city competitiveness, asseen in the urban liveability ratings of the Economist
Intelligence Unit, with Australian cities (EIU 2016)
populating the top 10. Aside from infrastructure andmobility, air pollution is one of the main challenges
in effective urban management (IEA 2016). Poor air
quality has implications for local economies and job
markets as measured through lost labour
output, and acutely represented by South Asia,
which loses as much as 0.83 per cent of its
GDP to air pollution (Figure 1.24).
1.5.2.3 Regional issues impacting air quality
An important aspect of air pollution is transboundary
haze emanating from the open burning of vast
areas of forests and plantations in the region.
Largely composed of PM 2.5 (ASEAN 2018),
these fires are also responsible for about 40
per cent of Indonesia’s overall greenhouse gas
emissions (ESA 2002). Because of its proximity
to urban centres, haze poses increased healthrisks for exposed populations, facilitates acidrain and affects economic activities. The 2015
haze episode in Singapore was estimated to havecaused US$ 700 million of losses (Barratt 2016)(Box 1.5). Although the Association of Southeast
Asian Nations (ASEAN) countries1, particularly
Indonesia, have passed several laws and policies
to control the fires and address the transboundary
problem – suspension of palm oil plantation
licences, prosecution of offending parties andpeatland conservation efforts (Lee and Shibao2016) – results have been limited at best. The
immense source of the problem calls for increased
investment to achieve a successful outcome.
When strong, turbulent winds disturb land surfacesthat are dry, unconsolidated (loose) and fine-grainedwith minimal or almost no vegetation cover, sandand dust storms can occur. This atmosphericphenomenon has hazardous health (section 1.2),
152

ASEAN: Brunei Darussalam, Cambodia, Indonesia, Laos, Malaysia,
Myanmar, Philippines, Singapore, Thailand, and Viet Nam.

agricultural (section 1.4.4) and socio-economic
impacts for many countries in the Asia and Pacificregion. Although partly a natural occurrence,sand and dust storms can be aggravated byunsustainable land and water management andparticles can be transported over long distances.
A recent policy review by Middleton and Kang
(2017) concluded that they directly affectapproximately 77 per cent of the countries thatare Parties to the United Nations Convention to
Combat Desertification (UNCCD), while only 23
per cent of them can be classified as source areas.
Aside from energy use, air pollution is largely
determined by how geography and, by extension,
climate conditions present distinct pollution
challenges. To illustrate, Iran’s capital Tehran
suffers from severe air pollution episodes during
winter. In November 2016, 400 people werereported to have died due to dense smog (Dehghan
2016). As a mountainous city with corresponding
atmospheric conditions, transport and industrial
emissions have led to severe episodes of air
pollution. This is also common among landlocked
cities in colder climates of Asia, such as Kabul,
Afghanistan; Kathmandu, Nepal and Ulaanbaatar,
Mongolia. Specifically, cities such as Kabul and
Ulaanbaatar, which are both home to 55 per cent of
the urban population in their respective countries,
expose their populace to chronic diseases related
to urban air pollution (UN-Habitat and UNESCAP
2015). On the other hand, due to their coastal
nature, Pacific island countries are less affectedby outdoor air pollution, despite concerns about
rising vehicle emissions in urban areas (ADB2012). Indoor air quality, however, is the relatively
more urgent concern (section 1.2) as the use of
traditional solid fuels such as wood is still prevalent(WHO 2002). Aside from this, air pollution has
been linked to increased weather variability (Oskin2014) (section 1.3).

> 15029
2

100-149

97

16

Concentration (μg/m3)

70-99

139
57

50-69

93
97

40-49

3

13

54
97

30-39

7

27

20-29

15

< 20

1
17

0

77

1

69

17

PM10 – Developing cities
PM10 – Developed cities

9

PM2.5 – Developing cities
PM2.5 – Developed cities

15

20

40

60

80

100

120

140

160

Number of cities
Note: Data for the last available year in the period 2012–2016.

FIGURE 1.23: ANNUAL AVERAGE PM2.5 AND PM10 CONCENTRATIONS IN ASIAN CITIES
Source: Data collected from publicly available sources compiled by WHO and Clean Air Asia

0.90

0.83

GDP equivalent (%)

0.80
0.70

0.61

0.60

0.53

0.50
0.30
0.20
0.10
0.00

0.44

0.39

0.40
0.25

0.23

0.15 0.16

0.13 0.12
0.02

East Asia
and Pacific0.13
0.04 0.02

Europe andCentral Asia

0.09

0.14 0.13
0.05

Latin America
and Carribbean

Total Air Pollution

0.110.10
0.01 0.02

0.01

Middle Eastand North
AfricaAmbient PM2.5

0.00

0.05

North America

Indoor Ambient O3

0.09
0.01

South Asia

Sub-SaharanAfricaAmbient ozone

Note: Total air pollution damage includes ambient and indoor PM2.5 and O3.

FIGURE 1.24: LABOUR OUTPUT LOST DUE TO AIR POLLUTION, BY REGION, 2013
Source: World Bank Group and IHME 2016

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

53

BOX 1.5: REGIONAL HAZE EFFECTS IN SINGAPORE
Although the Singapore National Environment Agency tracks air pollutant data, it is unable toprovide details of how much haze episodes contributed to the annual mean concentration of air
pollutants. However, it is possible to make inferences based on the ambient level of pollutants of ayear impacted by haze compared to one which is not. For example, the annual mean of PM2.5 andPM10 in 2015, a year impacted by haze, was significantly higher than in 2016, a year not impacted
by haze, as shown in the table below.
Pollutant

Averaging time

2015

2016

2020 air quality target1

PM10

24-hour3

186

61

50

(µg/m3)

Annual

37

26

20

PM2.5

24-hour3

145

40

37.5

(µg/m3)

Annual

24

15

12

Ozone

8-hour2

152

115

100

NO2

1-hour2

99

123

200

(µg/m3)

Annual

22

26

40

CO

1-hour2

3.5

2.7

30

(mg/m3)8-hour2

3.3

2.2

10

SO2

24-hour2

75

61

50

(µg/m3)

Annual121315(µg/m3)

The Pollutants Standard Index (PSI) for Singapore also shows that the percentage of days withunhealthy air quality in 2015 was higher than in 2016 – the PSI includes SO2, PM10, PM2.5, NO2, CO
and O3. Beyond health implications, haze pollution also has significant economic costs and impacts on
climate change. According to the World Bank, the 2015 haze episode cost Indonesia at least US$ 16.1
billion, equivalent to 1.9 per cent of Indonesia’s 2015 GDPa. Domestically, the 2015 haze episode cost
Singapore an estimated SG$ 700 million in lossesb. There is also an ongoing regional study to assess
the economic, social and health impacts of haze for Southeast Asia, which will allow affected countries
to better understand the impact of transboundary haze and supplement existing estimates on thecost of the 2015 haze episodec.
Apart from particulate matter, forest fires are also a major source of the greenhouse gas CO2, thus
contributing to climate change. The 2015 haze episode saw a huge release of natural carbon stores,
particularly from the burning of peatland. According to the World Resources Institute, daily estimatedgreenhouse gas emissions from fires in Indonesia exceeded the average daily CO2 emissions of theentire US economy (15.95 million tonnes of CO2 per day) on 26 out of 44 days from early September tomid-October 2015d. A recent study conducted by scientists from the UK, Indonesia and the Netherlands
concluded that the 2015 forest fires in Indonesia had generated about 850 million tonnes of CO2, withdaily emissions from September to October 2015 exceeding the combined emissions of the European
Union during the same periode.
Notes: 1 Singapore’s 2020 air quality targets are benchmarked against the WHO’s Interim Targets and air quality guidelines.
For SO2 and PM2.5, Singapore’s Sustainable Blueprint 2020 annual targets are 15µg/m3 and 12µg/m3 respectively.
2 Maximum 24-hour, 8-hour or 1-hour. 3 99th percentile.

54

BOX 1.5: REGIONAL HAZE EFFECTS IN SINGAPORE (contd.)a http://documents.worldbank.org/curated/en/776101467990969768/The-cost-of-fire-an-economic-analysis-of-Indonesia-s-2015-fire-crisis;b http://www.channelnewsasia.com/news/singapore/haze-episode-cost-singapore-estimated-s-700m-last-year-

masagos-8147924;

c http://www.straitstimes.com/singapore/environment/regional-study-to-be-done-on-economic-health-and-social-

impact-of-haze-in-2015;d http://www.wri.org/blog/2015/10/indonesia%E2%80%99s-fire-outbreaks-producing-more-daily-emissions-entireus-economy;e https://www.reuters.com/article/us-indonesia-haze/southeast-asian-fires-emitted-most-carbon-since-1997-scientistsidUSKCN0ZE210. Further information on air quality and haze can also be found in the National Environment Agency(NEA)’s website (http://www.haze.gov.sg/air-quality-information).
(Notes a–e are un-peer reviewed sources)

1.5.3. Air quality and the Sustainable
Development Goals
A recent study estimates that deaths induced by air
pollution cost the global economy about US$ 225
billion in lost labour income in 2013 (World Bank
Group and IHME 2016). For sustainable economic
growth, air quality management is becoming
one of the most important concerns in the world.
According to the US Environmental Protection
Agency, air quality management is defined as all
activities stemming from regulatory authority toprotect human health and the environment fromthe harmful effects of air pollution. In terms ofgovernment, it refers to policy support to reduce
air pollution. Various governmental policies aimed
at improving air quality have achieved noteworthy
outcomes. Many current air quality improvement
measures, however, seem to have reached theirlimitations, especially for O3 and particulate matter,
due to a myriad of complex factors, including thesoaring numbers of vehicles and the chemical
production and transport of these pollutants inthe atmosphere over large distances (General
introduction, Figures A and B).
While a number of studies have estimated thecost of ambient air pollution (OECD 2016; WorldBank Group and IHME 2016; OECD 2014), only two
studies have carried out comprehensive cost-benefit
analyses of air quality management policies in
the Asia and Pacific region. Some studies on
the cost-benefit analysis and welfare cost of air
pollution reduction policies are reported in Tables
1.3 and 1.4.

Crane and Mao (2015) provided rough estimates ofthe potential costs to China of adopting extensive
additional measures to reduce air pollution. Even
though they did not investigate the impact ofeach policy on urban air pollution, the total benefitof pollution control policies exceeds three times
that of the costs. Gao et al. (2016a) conducted acost-benefit analysis of implementing industrial
energy-saving and emission-reduction policies in
31 provinces for the period of 2013–2017. In thisstudy, they also carried out a scenario analysis
to assess the cost-effectiveness of individualenergy-saving measures and emission reduction
policies. Chae and Park (2011) also quantified
costs and benefits of air quality management
policies in the Seoul Metropolitan Area of the
Republic of Korea with several different emission
reduction scenarios. Even though their results
indicate that reduction policies in Seoul are
cost-effective, typical benefit-cost ratios cannot be
generalized since they do not follow a conventional
cost-benefit analysis framework.
Although there are positive benefit-cost results
and accelerated implementation of many air
pollution control measures in countries such as
China, according to projections of the Organisation
for Economic Co-operation and Development(OECD), a significant increase in global emissionsof air pollutants is expected due to economic
growth and energy demand. Consequently, thiswill be a tremendous regional burden in attaining
sustainable development.

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

55

TABLE 1.3: COST-BENEFIT ANALYSES OF AIR QUALITY MANAGEMENT STUDIESPolicy measure

SectorPollutant

Country

B/C (ratio)

Study

Replacingcoal with natural gas

Residential,commercial

SOx, PM,
NOx

China

Approximately
3 times cost

Crane andMao (2015)

Replacing coal-fired
electricity withother fuels

Power
generation

SOx, PM,
NOx

China

Approximately
3 times cost

Crane andMao (2015)

Scrapping older
vehiclesTransportation

SOx, PM,
NOx

China

Approximately
3 times cost

Crane andMao (2015)

Energy-saving

All sectors

SO2, NOx,
PM10

China

Yuan 146 billion(NPV)

Gao et al.
(2016)

End-of-pipe treatment

All sectors

SO2, NOx,
PM10

China

Yuan 516 billion(NPV)

Gao et al.
(2016)

Integrated policies

All sectors

SO2, NOx,
PM10

China

Yuan 629 billion(NPV)

Gao et al.
(2016)

Light-duty vehicle
emission standards

Transportation

PM2.5, O3,
NO2

China,
GuangdongMore than
3 times

Shao et al.
(2017)

Integrated policies

All sectors

NOx, PM10,
CO2

Republic of
Korea

-

Chae and Park(2011)NPV – net present value

The growing problem of poor air quality andthe linked climate-driven impacts represent atremendous regional burden and substantial barrier
to attaining sustainable development. While there
is no explicit reference to air pollution or air quality
management in the 17 SDGs, the consequences
and sources of air pollution impact many of them
(Figure 1.25). Failure to address air pollution will
directly threaten the success of SDG 3 which aims
to ‘ensure healthy lives and promote well-being for
all at all ages’, SDG 11 that aims to ‘make cities
and human settlements inclusive, safe, resilient,and sustainable’, and SDG 12 on ‘responsible
consumption and production’. Moreover, thesuccess of SDG 13 on climate action is inherently
linked with air pollution due to common emission
sources of air pollutants and greenhouse gases

56

and their overlapping, nonlinearly associatedimpacts on climate, human health, agriculture andecosystems (Melamed et al. 2016).
Despite its inherent complexities and projecteddifficulties related to effective implementation of
appropriate measures, air quality management
is just too important to dismiss as it is a criticalcomponent of sustainable development.
1.5.4 Conclusions• Considerable reductions in pollution have		 been achieved in Asia and the Pacific, where		 policy interventions have helped break the		 historical link between economic growth and		 pollution. Informed policy decisions along

TABLE 1.4: TOTAL WELFARE COSTS OF AIR POLLUTION, CENTRAL PROJECTION (2010 US$)
OECD

World

2015

2060

2015

2060

TOTAL market impacts(US$ billions)

90

390

330

3,300

Share of income (%)

0.3

0.5

0.6

1.5

Per person (US$)

70

270

50

330

TOTAL market impacts(US$ billions)

1,550

3,750–3,850

3,440

20,540–27,570

Share of income (%)*

5.0

5.0

6.0

9–12

Per person (US$)

1,210

2,610–2,680

470

2,060–2,770* Welfare costs from non-market impacts are not related to expenditures and therefore not an integral part of the calculation of income;the expression of these welfare costs as share of income is therefore only for illustrative purposes.
Source: OECD 2016

CitiesHealthEnergyGender

Air quality
HungerPoverty
Water

Inequality

ClimatechangeSustainable consumption
and production

Education

Growth andemployment
OceansSDGs with strong links to air quality
SDGs with/without links to air quality

Peaceful andinclusive society

Infrastructure andindustrialization
Terrestrial
ecosystems

Air quality (not a part of SDGs)

FIGURE 1.25: LINKS BETWEEN AIR QUALITY AND THE SUSTAINABLE
DEVELOPMENT GOALS
Source: modified from Le Blanc 2015

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

57

		 with a strong national mandate for sustainable		 growth, such as a continuing and increasing		 attention to clean energy, have the potential to		 reduce both air pollutant and CO2 emissions,		 while facilitating high levels of economic
		 growth to reduce poverty.

• A number of cost-benefit studies in Asia show		 that the total benefits of pollution control
		 policies greatly exceed their costs. Although		 there is accelerated implementation of many		 air pollution control measures in countries, a		 significant increase in emissions of air
		 pollutants is expected due to economic
		 growth and energy demand. Consequently,
		 this will be a tremendous regional burden in
		 attaining sustainable development.
• The economic development of the region’s		 41 countries varies widely, with national GDPs
		 ranging from hundreds of dollars per person		 per year to more than US$ 80,000. The data		 suggest that high-income countries in the region
		 have annual average population-exposure air
		 pollution levels below 30 μg/m3 of PM2.5 and		 that trends from 1995 to 2014 are stable.
		 There are few data available on low-income
		 countries. Middle-income countries have quite
		 variable annual average PM2.5 concentrations,		 ranging from about 5μg/m3 to more than		 85 μg/m3.
• Air quality is one of the main determinants
		 of environmental quality in city competitiveness,
		 as seen in the urban liveability ratings. Cities		 that wish to be globally competitive need to		 consider air quality as a serious issue.
• Further action is still needed to move towards
		 air quality levels that conform to WHO
		 guidelines for public health protection. These		 guidelines are aligned with the national air
		 quality standards adopted by countries in		 Asia and the Pacific. Further action should
		 reflect the diversity of the region in terms of		 stages of development, levels of capacity and		 availability of resources.

58

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

59

CHAPTER

2

Scenarios andsolutions2.1 INTRODUCTION
2.1.1 Modelling the region
The modelling studies reported in this chapter wereconducted using data on emissions and ambientconcentrations of the relevant pollutants in Asia.
The absence of data of a suitable quality for large
areas of the Pacific prevented modelling to thenecessary level of reliability for the entire Asia andPacific region.
Results are presented as aggregates for four
sub-regions (Figure 2.1). While broadly based on
the sub-regions defined by the UN Environment
Asia and Pacific Office, countries were re-grouped
for the purposes of modelling to take account of
the availability of data and ensure the scientificconsistency of the modelling results. These
sub-regions are used for scientific convenienceand have no official or administrative significance,
and are composed as follows:• East Asia (modelled East Asia) includes China,
		 Democratic People’s Republic of Korea and		 Mongolia (and excludes Japan and Republic
		 of Korea);• Southeast Asia (modelled Southeast Asia)
		 includes Cambodia, Indonesia, Lao People’s		 Democratic Republic, Malaysia, Myanmar,
		 Philippines, Thailand and Viet Nam (and		 excludes Brunei Darussalam and Singapore);• South Asia (modelled South Asia) includes
		 Afghanistan, Bangladesh, Bhutan, India, Iran,		 Maldives, Nepal, Pakistan and Sri Lanka;• High-income countries (modelled high-income
		 countries) include Brunei Darussalam, Japan,
		 Republic of Korea and Singapore.

2.1.2 Background
Rapid economic growth has led to high levels of
air pollution throughout Asia, causing social, publichealth and environmental problems that add tothe challenges of sustainable development. Many
Asian countries have initiated action to reduce62

emissions of air pollutants; often, however, theirbenefits are counteracted by further economic
growth and are therefore not always visible.
World-wide experience clearly demonstrates thatclean air can be achieved without compromisingsocial and economic development. To be mostsuccessful, this requires well-designed policies
that prioritize, for specific conditions, cost-effective
interventions for the sources that deliver thelargest benefits, and that are well integrated withother development targets. This assessment
highlights how much progress has been madein Asia in decoupling air pollution trends from
economic growth (Figure 2.4), and demonstrates
a clear potential for further progress in line withaspirations for sustainable development andprotection of human health and the environment,
including the climate.
While there is ample experience from Europe, North
America and other areas that could help improve
the situation in Asia further, this cannot be directlytransferred to Asia due to differences in economic
development, social conditions, meteorologicalfactors and institutional settings.
With a focus on Asia, this chapter presents ananalysis of promising air quality management
options that could effectively improve air quality
in Asia and contribute tosustainable economic
development.
The objective of this chapter is to identify concrete
air quality management options that can provide
optimum benefits in the wider context ofsustainable development, using robust scienceand a comprehensive approach. It is organized asfollows: the first section introduces the conceptual
framework that has been used for the assessmentof effective policy intervention options and briefly
introduces the tools and assumptions that have been
employed. Subsequently, the chapter presents key
findings, with graphs and some explanatory notes.
More detailed information is provided in Annex 2.1.

2.2 APPROACH AND METHODOLOGY
2.2.1 Air quality management options withmultiple benefits for development
This chapter explores air quality management
options for Asia with simultaneous benefits for air
quality and other development objectives (Figure 2.2).

• First, the analysis explores the factors that		 determined the historic development of air
		 pollutant emissions in Asia, and extrapolates		 emissions up to 2030, taking into account		 emissions control legislation that has already		 been implemented or adopted by Asian		countries.
• Second, it assesses the scope for further
		 reductions in air pollutant emissions from		 three sets of measures:- a full Asia-wide application of the measures		 that proved effective in the past for Asian		conditions;- next-stage Asia-specific air quality measures		 that address the remaining priority
		 emission sources in Asia;- other measures that contribute to		 development priorities.

• Third, the chapter determines for these three
		
		
		
		

portfolios the impacts of each measure on
population exposure to harmful fine particulatematter (PM2.5) in Asia and identifies thosemeasures that deliver the greatest benefits.

• Finally, the impacts of these measures on		 human health, agricultural crop yields and		 temperature increase are assessed, and their		 contributions to the achievement of the		 Sustainable Development Goals (SDGs) are		 characterized in qualitative terms.
Integrated perspective based on state-of-the-art
methods
Identifying promising policy intervention options
that could deliver effective improvements in air
quality in Asia together with progress towards the
SDGs requires an holistic perspective that integrates
geo-physical, economic, social and institutional
dimensions across different spatial and temporalscales. This analysis achieves such a perspective
through a suite of well-established scientific toolsthat cover the different elements (Box 2.1).

East Asia
High-income countries
South Asia
Southeast Asia

FIGURE 2.1: MODELLED SUB-REGIONS OF ASIA

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

63

Reduce exposure to outdoor and indoor air pollution

Asia-wide application of
conventional measures

Human health
EconomyNext-stage
Asia-specific measures

Food
Ecosystems

Measures contributing todevelopment goals

ClimateSustainable Development Goals

FIGURE 2.2: CONCEPTUAL APPROACH FOR IDENTIFYING EFFECTIVE AIR QUALITYMANAGEMENT MEASURES THAT ALSO CONTRIBUTE TO THE CLIMATE AND
SUSTAINABLE DEVELOPMENT AGENDAS

Capturing diversity for tailored findings

2.3 KEY FINDINGSDiversity is a distinguishing feature of Asia. As aconsequence, any effective clean air strategy willvary in approach based on the context of eachcountry and/or city, as well as its capacity to develop
and implement measures. There is no uniform policy
prescription for air quality that is applicable to all
countries and regions; such an approach would
neither be possible nor desirable for a problem thatis so diverse in local circumstances.

2.3.1 Success in breaking the historic link
between economic growth and pollution

To capture the multiple dimensions of Asian
diversity, the current analysis was carried out for
100 emission source regions in Asia, distinguishingthe individual states and provinces of large countries,
as well as megacities (Annex 2.1). Impacts onambient air quality and population exposure werecomputed for 1,275 individual cities, as well as forrural areas with a spatial resolution of 0.5 x 0.5
degrees – approximately 40 x 50 kilometres (km).

64

From 1990 onwards, all PM 2.5 precursor
emissions in Asia grew steadily. Particularly large
increases occurred for sulphur dioxide (SO2) andnitrogen oxides (NOx), which closely followed the
expansion of economic activity as measured bygross domestic product (GDP). Emissions forwhich non-industrial sources are more important,such as volatile organic compounds (VOCs)
and primary emissions of PM2.5 from residential
combustion of biomass, or ammonia (NH3) fromagricultural activities, developed along less steep
growth paths (Figure 2.4).
After 2005, however, policy interventions – especiallysulphur controls at power plants in China and theintroduction of emissions standards for vehicles –BOX 2.1: MODELLING TOOLS USED IN THIS ANALYSISThe analysis employs a series of well-established scientific tools and methods that put the relevant
aspects in context with each other for the quantification of potential benefits (Figure 2.2).
The Greenhouse gas – Air pollution Interactions and Synergies (GAINS) model (Amann et al. 2011)
quantifies the drivers, mechanisms and impacts of emissions, and explores options for reducing
impacts in cost-effective ways. Projections of future economic activity, energy use and agricultural
production are derived from the analyses of the International Energy Agency (IEA), presented inits 2016 World Energy Outlook Special Report: Energy and Air Pollution (IEA WEO 2016), and the
Food and Agriculture Organization of the United Nations (FAO). Current emissions are estimatedbased on international activity statistics, with emission factors reflecting local conditions in 100
regions of Asia. Considering about 2,000 emission reduction options, their impacts on ambient air
quality and population exposure are computed for 1,275 urban areas across Asia and surrounding
rural regions, based on the results of the European Monitoring and Evaluation Programme(EMEP) atmospheric chemistry and transport model (more details are provided in Annex 2.1).
As an indicator for population exposure to particulate matter (PM), this report employs the annual
average population-weighted mean exposure to ambient PM2.5, accumulated over the full population,
as the central metric. Following the method adopted by the World Health Organization (WHO)for the 2016 Global Burden of Disease study (WHO GBD 2016), health impacts from exposure toPM2.5 and ozone (O3) in ambient air and to indoor pollution are quantified, and their uncertainties
estimated with alternative parametrizations that have been used for similar assessments. The
analysis in this report is restricted to premature mortality and does not address the morbidity
impacts of pollution.
The impacts of emission changes on temperature increase and other climate indicators are calculatedwith the Goddard Institute for Space Studies (GISS) and Goddard Earth Observing System (GEOS-Chem)models of the National Aeronautics and Space Administration (NASA) (Schmidt et al. 2014; Shindell
et al. 2013), and a parametrization using the Absolute Global Temperature Potential (AGTP)(Shindell 2015). Crop losses from O3 are estimated based on standard global DO3SE methods
used by the Stockholm Environment Institute (SEI). Further details are provided in Annex 2.1.

led to a distinct decoupling of SO2 and NOx emissions
from economic growth, while PM2.5 emissions
remained relatively flat1 (Figure 2.4). In contrast, inthe absence of policy interventions, emissions of NH3
continued to grow as a consequence of increasing
agricultural production.
By 2015, SO2 emissions in Asia had declined by
15 per cent relative to 2005, despite the 63 percent growth in GDP. Without the implementationof control measures, emissions would havebeen 80 per cent higher, and without the energy

policy measures 95 per cent higher. Nitrogen oxide
emissions grew by 27 per cent, with emission
controls avoiding a further 22 per cent increase.
Energy policy, especially the shift from coal andbiomass to cleaner fuels, avoided a 50 per centincrease in primary emissions of PM2.5, and dedicatedpollution controls avoided a 20 per cent growth(Figure 2.7). Together, these policy interventions
resulted in a stabilization of PM2.5 emissions.

1 The trends for Asia illustrated in Figure 2.4 are largely driven by recent
policy developments in China; the trends for the four modelled
sub-regions of Asia (Figure 2.3) are shown in Figure 2.28.

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

65

IEA WEO + FAO

Future economic activities

Energy and agricultural scenarios

Sustainable Development Goals

GAINS

Emission control measures

GISS and GEOS-Chem
Emissions of air pollutants
and greenhouse gases

Climate impacts
Ozone concentrations

DO3E
Ambient air quality PM

Crop impacts

WHO GBD
Population exposure toambient PM and indoor pollution

Health impacts

FIGURE 2.3: THE SUITE OF MODELS USED FOR THIS ANALYSIS AND
THE INTERACTIONS BETWEEN MODELS

Index (1990 = 100)

GDP
SO2
NOX
PM2.5
NH3
VOCS

SO2 – sulphur dioxide; NOx – nitrogen oxides; NH3 – ammonia; VOCs – volatile organic compounds

FIGURE 2.4: THE EVOLUTION OF GDP AND THE POLLUTANTS
THAT CONTRIBUTE TO PM2.5 FORMATION IN ASIA, 1990–2015
Source: IEA WEO 2016; GAINS model estimates66

2.3.2

Measuring atmospheric pollutants

While monitoring data are not available for all cities
and locations in Asia, air quality across Asia can bemodelled with atmospheric chemistry-transportmodels using the best information available onemissions and meteorological conditions.
For 2015, particularly high levels were calculated
for urban and heavily industrialized areas withhigh population densities, for example in many
cities in the northeast of China and in the Ganges
valley (Figure 2.5). In addition, high concentrations
occurred in areas with large sources of natural soil
dust from drylands such as the Gobi Desert and inlarge parts of western Asia.
The 2015 concentrations shown in Figure 2.5 werecomputed with the GAINS model, using emission
estimates developed for the model (Klimont et al.
2017; IEA WEO 2016; Klimont et al. 2013). Results
agree well with observations as well as withother model calculations, such as the NAQPMS
model of the Institute of Atmospheric Physics of
the Chinese Academy of Sciences (CAS) in Beijing,
and the MICS-Asia model inter-comparison
for Asia (Gao et al. 2018); see Annex 2.1 for a
detailed comparison.
Pollutant levels continue to exceed national andinternational air quality standards
Despite the recent declines in total SO 2 andNOx emissions, a large quantity of air quality
monitoring data provides ample evidence thatnational and international air quality standards(Table 2.1) are currently widely exceeded in Asia.
Model calculations that cover all of Asia indicatethat PM 2.5 concentrations in ambient air
exceeded the international WHO Guideline valueof 10 micrograms per cubic metre (µg/m3) overlarge areas, and essentially in all populated regions(Figure 2.5). Furthermore, concentrations exceeded
the highest WHO Interim Target level 1 (35 µg/m3)
in many areas.

In 2015, less than 8 per cent of the Asian
population enjoyed air quality that
conforms to the WHO Guideline

A comparison of the PM2.5 fields with population
data reveals that in 2015 less than 8 per centof the Asian population could breathe air that
conforms to the WHO Guideline for PM2.5 of
10 µg/m3. In contrast, more than half of the Asian
population, about 2.3 billion people, faced exposurethat exceeded even the highest WHO Interim
Target of 35 µg/m3 (Figure 2.6). Between 2005
and 2015, population-weighted mean exposure
increased by about 10 per cent and reached
43 µg/m 3 , more than four times the WHO
Guideline value.
In addition, in 2015 almost 1.9 billion people sufferedfrom exposure to indoor pollution as a consequenceof burning solid biomass or coal in cookstoves.
2.3.3 Energy policy and pollution control
Many Asian countries have established ambitious
targets for reducing the energy intensity of theireconomies through dedicated energy efficiency
policies and a restructuring of production towards
less energy-intensive products, meaning that in the
future, energy consumption trends will decouple
from economic growth even more than in the past.
In addition, countries are aiming to transform theirenergy systems, with a less prominent role for fossil
fuels such as coal and oil. As a consequence, therecent projections of future energy use publishedby the IEA (IEA WEO 2016) foresee growth intotal primary energy consumption of 25 per centbetween 2015 and 2030, much less than the
80 per cent increase in GDP that is assumed
for the same period.

Energy policy and the enforcement ofstrengthened pollution control measures
will remain key determinants for a further
decoupling between economic growthand pollution in Asia
However, despite these energy policies, the 25
per cent higher energy consumption will further
enhance the pressure on air quality in Asia.
Technical means exist to reduce emissions, andimportant measures have already been adopted
by legislation that should lead to lower emissions
in the future if they are effectively implemented.

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

67

105

65

50
WHO Interim Target 1

PM2.5 (μg/m3)

80

35
25
15
10

WHO Guideline

FIGURE 2.5: AMBIENT LEVELS OF PM2.5 IN ASIA IN 2015
Source: GAINS 2017

TABLE 2.1: NATIONAL AIR QUALITY AND GLOBAL GUIDELINES FOR PM2.5
Annual mean PM2.5
concentration

WHO
Air Quality CriteriaIndia

40 μg/m3
35 µg/m3

WHO Interim Target 1

China Grade IIa
Malaysia

25 µg/m3

WHO Interim Target 2

Mongolia
Philippines
Sri Lanka
Thailand
Viet Nam

15 µg/m3

WHO Interim Target 3

Bangladesh
China Grade Ib
Indonesia
Japan
Pakistan
Republic of Korea
Singapore

12 µg/m3
10 µg/m3

WHO Guideline

8 µg/m3 c
a Natural Protection Area and other areas which need special protectionb Residential, commercial, industrial and rural areac Maximum concentration

68

National air quality
standards

Australia

In addition, a wealth of further measures, often
for emission sources that are not addressedby current legislation, could deliver substantial
additional emission reductions throughout Asia.
The effectiveness of implementation andenforcement of existing control measures will havea crucial impact on future emission levels. By 2030,
without the policies and measures put in place andenforced in the last decade, SO2 emissions in Asia
would likely be almost three times greater thanin 2015, given the expected further 80 per centincrease in GDP. However, the measures introduced
after 2005 cut emissions by about 40 per cent by
2015 and will continue to do so in future if effectively
enforced. Together with current energy policy
measures – to reduce energy intensity and phaseout solid fuels – they would limit the emissions
increase in 2030 to about 20 per cent compared
to 2015. If all countries enforced the emission
controls that they have already included in theirlegislation but that are not yet implemented, AsianSO2 emissions would shrink by 20 per cent from2015 levels. Full application of all available controls
could cut SO2 emissions by 60 percent (Figure 2.7).
A similar picture emerges for emissions of NOX,
which would be 100 per cent higher by 2030
compared with 2015 levels in the absence of any

emission controls. Energy policy measures
together with existing emission controls would
limit the increase in emissions to 25 per cent above
2015 levels, while a timely enforcement of recent
legislation would deliver a 15 per cent reduction inemissions compared with 2015 levels. Overall, thereis scope for a 50 per cent reduction in emissions ofNOx compared with 2015.
Primary emissions of PM2.5 would double by 2030
compared with 2015 levels in the absence of any
measures. The already implemented controls,
together with energy policies that promote lesspolluting fuels in the household sector, will reduce
the growth to 5 per cent, and an enforcement of
all recent legislation should deliver a 10 per centreduction in emissions compared with 2015 levels.
Emissions could be cut by 75 per cent by 2030 withthe full application of all available measures.
In contrast, population growth and dietary change
will lead to greater agricultural production,
especially of livestock, which will increase NH3
emissions in the absence of policies stimulatingand enforcing emission controls. In addition,
persistent over-fertilization and strong relianceon urea and ammonium bicarbonate mineral
fertilizers result in significant losses of nutrients andconsequently NH3 emissions to the atmosphere.

All Asia

East Asia

South Asia

< WHO Guideline (10 μg/m3)< WHO Interim Target 1 (35 μg/m3)

Southeast Asia

35–50 μg/m3
50–65 μg/m365–80 μg/m3> 80 μg/m3

High-income
countries
0

1

2

3

4

People exposed to indoor pollution

Billion people exposed to PM2.5 in 2015

FIGURE 2.6: DISTRIBUTION OF POPULATION EXPOSURE TO AMBIENT PM2.5 AND
INDOOR POLLUTION IN 2015, ASIA-WIDE AND FOR THE MODELLED SUB-REGIONS
Source: GAINS 2017
AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

69Current policies will avoid a further
deterioration in air quality at the large
scale, but will not be sufficientto achieve air quality standards
Need to build on current policy
Asia’s policy decisions are not only critical forcontrolling future emissions, but equally for the
resulting air quality. Hypothetically, without any policy
interventions, population-weighted mean exposure
to PM2.5 would grow by almost 50 per cent by 2030,
from 43 µg/m3 in 2015 to about 62 µg/m3. ThisThe already implemented measures reduce thehypothetical growth by about 11 µg/m3 by 2030,
and a further 9 µg/m3 reduction would result
from an effective enforcement of all recently
decided emission control legislation. Thereby,on average, current legislation will maintainpopulation-weighted mean exposure at the current
levels, and thereby compensate the impacts of the
expected 80 per cent economic growth.

Nitrogen oxides

Index (1990 = 100)

Index (1990 = 100)

Sulphur dioxide

is a consequence of higher precursor emissions
combined with continued urbanization trends, which
will increase the share of the urban population in Asia.

Avoided through already
implemented measures
Avoided through energy
intensity improvements

Ammonia

Index (1990 = 100)

Index (1990 = 100)

PM2.5

Avoided through switch tocleaner fuels
Benefits from full implementationof current legislation

Scope for further measures
Residual emissions
GDP

FIGURE 2.7: THE CONTRIBUTIONS OF DIFFERENT POLICY INTERVENTIONS TO THE
DECOUPLING OF ECONOMIC GROWTH FROM EMISSIONS OF PM2.5 AND ITS PRECURSORSUNDER CURRENT LEGISLATION UP TO 2030, FOLLOWING THE IEA WEO ENERGY SCENARIO,
AND SCOPE FOR FURTHER EMISSION CONTROLS

70

However, current legislation will not be sufficient toimprove air quality to such an extent that national
and international air quality standards will be met.
Despite some decline in ambient PM2.5 in Eastern
Asia, large exceedances of air quality standards
will remain in heavily industrialized areas with highpopulation densities (Figure 2.8). In Western Asia,
ambient PM2.5 levels would grow further undercurrent legislation, adding to the high load fromnatural sources, particularly soil dust.

Some 2.4 billion people – 54 per cent of
the population – will suffer from PM2.5
levels above the highest WHO Interim
Target, and 1.3 billion people will remain
exposed to indoor pollution

2.3.4 The top 25 clean air measures for Asia
In total, more than 2,000 emission control options
were considered in the analysis. Of these, 25
measures were identified that deliver the greatest
benefits for human health from reduced exposure
to ambient and indoor air pollution in Asia, while atthe same time contributing to development priority
goals. The full set of top 25 measures is grouped into
three categories (Table 2.2).

Measures that are widely adopted in thecurrent emission control legislationof Asian countries will avoid a further
deterioration of air quality
The contribution of conventional measures

Overall, limited improvements in air quality fromcurrent policies will not significantly reduce total
population exposure to harmful PM2.5 pollution
compared to today. By 2030, still only 8 per centof the Asian population, around 363 million people,
will live with air quality that complies with the
WHO Guideline. About 2.4 billion people, 54 percent of the total population, will still face PM2.5
levels in excess of the highest WHO Interim Target
level 1 (35 µg/m3). In addition, 1.3 billion people willremain exposed to indoor pollution (Figure 2.9).

By now, many Asian countries have adopted – andpartially implemented – effective measures tocontrol air pollutant emissions, which in practicedecouple economic growth from emission trends.
Most of these measures focus on emission sourcesthat exhibit rapid growth with increasing levels of
economic activity, such as large combustion plants,
industrial processes and mobile sources (Table 2.3).
Especially effective are post-combustion
emission controls at large plants in the power
and industrial sectors, emissions standards for

105

65
50
WHO Interim Target 1

PM2.5 (μg/m3)

80

35
25

WHO Guideline

15
10
0

FIGURE 2.8: AMBIENT LEVELS OF PM2.5 IN ASIA IN 2030
UNDER CURRENT LEGISLATION
Source: GAINS 2017

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

71

at today’s level, compensating the impacts of thepredicted 80 per cent economic growth.

diesel and gasoline vehicles, and measures tocontrol emissions from industrial processes(non-combustion), including steel, cement andglass production. In addition, where implemented,
effective inspection and maintenance schemes forvehicles avoid substantial exposure (Figure 2.10).

An Asia-wide application of the conventional
measures (Table 2.3) in countries that have not yet
developed more advanced air quality control regimes,
such as in Southeast Asia, and the extension ofcurrent laws to smaller industrial sources in othercountries, for example in East Asia, can deliver
additional air quality improvements and reduce
population exposure by 8 µg/m3, taking it down toabout 35 µg/m3.

The future benefits of these policies and measuresdepend on the effectiveness of their implementation.
By 2030, currently implemented measures willrealize about 40 per cent of their full potential,
especially in East Asia and the high-income
countries. Another 40 per cent will depend ontimely implementation and effective enforcementof legislation that is already enshrined in law but not
yet implemented, predominantly in South Asia.

However, this level of exposure still fails to conformto most national and international air quality
standards, and large shares of the Asian population
will remain exposed to pollution levels that exceed
even the highest WHO Interim Target. Furthermore,such policies will not protect people exposed toindoor air pollution.

Asia-wide application of conventional
measures in countries that have not yet
developed more advanced air quality
control regimes can deliver additional
improvements

Any effective attempt to bring ambient
air quality levels down to national andinternational standards must include
further measuresThus, by 2030, over all of Asia, the measures that are
already implemented will reduce mean population
exposure to PM2.5 by about 11 µg/m3 compared toa hypothetical no-control situation. Full and timely
implementation of the policies that are already laid
down in legislation but not yet in operation would
deliver a further 9 µg/m3 reduction, so that on
average the mean population exposure would remain

Next-stage measures
Since the current measures offer only limited
potential for fundamental improvements in today’s
air quality, any effective attempt to bring ambient

Top 25clean airmeasures2030
Current
legislation
2030< WHO Guideline (10 μg/m3)< WHO Interim Target 1 (35 μg/m3)
35–50 μg/m3
50–65 μg/m365–80 μg/m3> 80 μg/m3

2015
0

1

2

3

4

People exposed to indoor pollution

Billion people exposed to PM2.5 concentrations

FIGURE 2.9: DISTRIBUTION OF POPULATION EXPOSURE TO PM2.5,
IN 2015 AND IN 2030 UNDER CURRENT LEGISLATION

72

air quality levels down to national and international
standards must include measures in sectorsthat do not feature prominently in current plans.
Today’s Asian portfolios of policy measures mainly
focus on emission sources that are growing rapidly
with economic development, including large

industrial and power plants and road transport,
but address small and dispersed sources suchas households, agriculture, waste burning andforest fires inadequately. More important in Asia
than on other continents, these sectors produce
considerable amounts of primary particulate

TABLE 2.2: THE TOP 25 CLEAN AIR MEASURES
Regional application of conventional measures
Post-combustion controls

Introduce state-of-the-art end-of-pipe measures to reduce
SO2, NOx and particulate emissions at power stations and inlarge-scale industry

Industrial process emissions
standards

Introduce advanced emissions standards in industries,e.g., iron and steel plants, cement factories, glass production,
chemical industry, etc.

Emissions standards for roadvehiclesStrengthen all emissions standards; special focus on
regulation of light- and heavy-duty diesel vehicles

Vehicle inspection andmaintenance

Enforce mandatory checks and repairs for vehicles

Dust control

Suppress construction and road dust; increase green areas

Next-stage air quality measures that are not yet major components of clean air policies
in many parts of Asia and the Pacific
Agricultural crop residues

Manage agricultural residues, including strict enforcementof bans on open burning

Residential waste burning

Strictly enforce bans on open burning of household waste

Prevention of forest and peatland
fires

Prevent forest and peatland fires through improved forest,
land and water management and fire prevention strategies

Livestock manure management

Introduce covered storage and efficient application ofmanures; encourage anaerobic digestion

Nitrogen fertilizer application

Establish efficient application; for urea also use urease
inhibitors and/or substitute with, for example, ammonium
nitrateBrick kilns

Improve efficiency and introduce emissions standards

International shipping

Require low-sulphur fuels and control of particulate
emissions

Solvent use and refineries

Introduce low-solvent paints for industrial and do-it-yourself
applications; leak detection; incineration and recovery

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS73

TABLE 2.2: THE TOP 25 CLEAN AIR MEASURES (contd.)
Measures contributing to development priority goals with benefits for air quality
Clean cooking and heating

Use clean fuels – electricity, natural gas, liquefied petroleum gas(LPG) in cities, and LPG and advanced biomass cooking andheating stoves in rural areas; substitution of coal by briquettes

Renewables for power generation

Use incentives to foster extended use of wind, solar and hydropower for electricity generation and phase out the least efficientplantsEnergy efficiency for households

Use incentives to improve the energy efficiency of household
appliances, buildings, lighting, heating and cooling;encourage roof-top solar installations

Energy efficiency standards forindustry

Introduce ambitious energy efficiency standards for industry

Electric vehicles

Promote the use of electric vehicles

Improved public transport

Encourage a shift from private passenger vehicles to public
transport

Solid waste management

Encourage centralized waste collection with source separationand treatment, including gas utilization

Rice paddies

Encourage intermittent aeration of continuously flooded paddies

Wastewater treatment

Introduce well-managed two-stage treatment with biogas
recovery

Coal mining

Encourage pre-mining recovery of coal mine gas

Oil and gas production

Encourage recovery of associated petroleum gas; stop routine
flaring; improve leakage control

Hydrofluorocarbon(HFC) refrigerant replacement

Ensure full compliance with the Kigali Amendment

emissions (PM2.5) as well as precursor gases suchas NH3 that contribute to and control the formationof secondary particles in the atmosphere.
Measures are available and proven that can
reduce these emissions, including the more
efficient use of fertilizers, prevention of forestand peat fires, a ban on open burning of agriculturalresidues and household waste, improved manure
management, and control of solvent emissions inindustry (Table 2.4).

74

A portfolio that includes these measures in
addition to the conventional ones could reduce
population exposure to PM2.5 in Asia by a further
6 µg/m3 (Figure 2.11), and thereby cut it by morethan one third compared to 2015, or by morethan half compared to the hypothetical situation
without any emission controls in 2030. It shouldbe mentioned that these measures, while not
yet applied at large scale in Asia, are importantelements of today’s air quality management
portfolios in other parts of the world, including
Europe and North America.

TABLE 2.3: EMISSION CONTROLS THAT ARE PROVEN AND WIDELY APPLIED IN ASIA
Regional application of conventional measures

Strengthen all emissions standards; special focus on
regulation of light- and heavy-duty diesel vehicles

Vehicle inspection andmaintenance

Enforce mandatory checks and repairs for vehicles

Dust control

Suppress construction and road dust; increase green areas

du
ad
Ro

Ind
em ustiss rial
ion pro
ce
s

co
on
sti
bu
om
t-c
Po
s

Reduction in population exposure to PM2.5 in 2030 (μg/m3)

st

Emissions standards for roadvehiclesVe
an hicled m inain speten ctian onceIntroduce advanced emissions standards in industries,e.g., iron and steel plants, cement factories, glass production,
chemical industry, etc.

ss

Industrial process emissions
standardsEm
fo issr r iooa ns
d v steh an
icl daes rdsIntroduce state-of-the-art end-of-pipe measures to reduce
SO2, NOx and particulate emissions at power stations and inlarge-scale industry

ntr
ols

Post-combustion controls

0
-2
-4
-6
-8
-10
-12
Already implemented measures

Recent legislation

Further potential

FIGURE 2.10: IMPACTS OF THE EMISSION CONTROL MEASURES THAT ARE NOW WIDELYAPPLIED IN ASIA ON POPULATION-WEIGHTED MEAN EXPOSURE TO PM2.5 IN 2030,
RANKED BY TOTAL EXPOSURE REDUCTION

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

75

TABLE 2.4: NEXT-STAGE AIR QUALITY MEASURES TO REDUCE PARTICULATE AND
PRECURSOR EMISSIONS
Next-stage air quality measures that are not yet major components of clean air policies
in many parts of Asia and the Pacific
Agricultural crop residues

Manage agricultural residues, including strict enforcementof bans on open burning

Residential waste burning

Strictly enforce bans on open burning of household waste

Prevention of forest and peatland
fires

Prevent forest and peatland fires through improved forest,
land and water management and fire prevention strategies

Livestock manure management

Introduce covered storage and efficient application ofmanures; encourage anaerobic digestion

Nitrogen fertilizer application

Establish efficient application; for urea also use urease
inhibitors and/or substitute with, for example, ammonium
nitrateBrick kilns

Improve efficiency and introduce emissions standards

International shipping

Require low-sulphur fuels and control of particulate
emissions

Solvent use and refineries

Introduce low-solvent paints for industrial and do-it-yourself
applications; leak detection; incineration and recovery

Action aiming to contribute todevelopment priorities can eliminate,
or at least reduce, some of the mostpolluting activities
Development priorities and air quality
The portfolios of conventional and next-stage
measures presented in Tables 2.3 and 2.4 havebeen compiled with a narrow focus on air quality.
Typically, such measures can be decided by
the authorities that are dealing with air quality
management, involving other relevant stakeholders
such as vehicle producers, power companies,
refineries or industrial organizations. However,there are additional measures that offer further
means of improving air quality, even if they do notprimarily target air pollution. Often, they fall under
the jurisdiction of different authorities and are
discussed in different policy frameworks in which
air quality managers are often not represented.
These include, inter alia, measures closely related76

to economic and social development, energy
or agricultural policies, or urban management.
In particular, action aiming to contribute to thedevelopment priorities reflected in various SDGs
can also eliminate, or at least reduce, some of
the most polluting activities, bringing additionalemission reductions that are usually beyond theimmediate jurisdiction of environmental authorities.
Relevant SDGs include, inter alia, SDG 6: Clean Waterand Sanitation, SDG 7: Affordable and Clean Energy,
SDG 11: Sustainable Cities and Communities, SDG
12: Responsible Consumption and Production, and
SDG 13: Climate Action.
To this end, the analysis explored measures aimed
at development priorities that affect the precursor
emissions of PM2.5 (Table 2.5), and whose potential
impacts on activity levels have been quantified in
the International Energy Agency (IEA) World Energy
Outlook Special Report: Energy and Air Pollution(IEA WEO 2016).

tPr
an evend p tioea n ot fi f f
res ore
s

ing
sh
ipp

So
an lvendr tu
efi se
ne
rie
s

on
al
Int

ern
a ti

kil
ns
ick
Br

Liv
m estoana g ck mmen anutreRewa sideste nti
bu al
rn
ing

Ag
cro ricu
p r ltur
es al
idu
es

Ni
ap trogpli enca fe
tio rtilizenrReduction in population exposure to PM2.5 in 2030 (μg/m3)

-0.0
-0.2
-0.4
-0.6
-0.8
-1.0
-1.2
-1.4
-1.6
-1.8
-2.0
Already implemented measures

Recent legislation

Further potential

FIGURE 2.11: IMPACTS OF ASIA-SPECIFIC NEXT-STAGE AIR QUALITY MEASURES ON
POPULATION-WEIGHTED EXPOSURE TO PM2.5 IN 2030, RANKED BY TOTAL REDUCTIONTABLE 2.5: MEASURES AIMED AT DEVELOPMENT PRIORITIES THAT REDUCE PM2.5
PRECURSOR EMISSIONS
Measures contributing to development priority goals with benefits for air quality
Clean cooking and heating

Use clean fuels – electricity, natural gas, liquefied petroleum gas(LPG) in cities, and LPG and advanced biomass cooking andheating stoves in rural areas; substitution of coal by briquettes

Renewables for power generation

Use incentives to foster extended use of wind, solar and hydropower for electricity generation and phase out the least efficientplantsEnergy efficiency for households

Use incentives to improve the energy efficiency of household
appliances, buildings, lighting, heating and cooling;encourage roof-top solar installations

Energy efficiency standards forindustry

Introduce ambitious energy efficiency standards for industry

Electric vehicles

Promote the use of electric vehicles

Improved public transport

Encourage a shift from private passenger vehicles to public
transport

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

77

c
Im
tra provns ed
port pub
li

rs
ca
ic
ctr
Ele

En
sta ergy
nd ef
ard fic
s – ienc
ho y
us
eh
o ld
s
En
e
r
sta gynd ef
ard fic
s – ienc
ind y
us
tr y

Re
po new
we a br g lesen
era for
tio
n

kin
g
oo
nc
ea
Cl

Reduction in population exposure to PM2.5 in 2030 (μg/m3)

-0
-1
-2
-3
-4
-5
-6
-7
Already implemented measures

Recent legislation

Further potential

FIGURE 2.12: IMPACTS OF DEVELOPMENT PRIORITY MEASURES ON
POPULATION-WEIGHTED EXPOSURE TO PM2.5 IN 2030, RANKED BY TOTAL REDUCTION

Following the assumptions about implementation
rates of the IEA WEO energy scenario, collectively
these measures could reduce population-weighted
mean exposure in Asia by another 8 µg/m3 in
2030 (Figure 2.12), and correspondingly more
thereafter, in addition to their primary benefits fordevelopment priorities.

ambient air in Asia would increase by about 50
per cent due to population growth, urbanization andeconomic development.

The growing threat of ozone

The measures in the conventional and next-stage
portfolios were identified with a clear focus on
PM2.5 precursor emissions in ambient air (NOx,
VOCs, SO2 and NH3). At the same time, whiletargeted at PM2.5, they also affect three out of thefour precursor emissions of ground-level O3, NOx,
VOCs and carbon monoxide (CO), reducing themby 50, 60 and 70 per cent, respectively, comparedto the current legislation case (Table 2.6).

Exposure to ground-level O3 is the second largest
risk factor for human health from ambient
pollution, albeit current quantifications suggest
much lower impacts than for PM2.5. In addition,
ground-level O3 causes significant damage tovegetation, including agricultural crops.

However, these measures will not affect methane(CH4) emissions, another precursor to ground-levelO3. Methane has a strong impact on backgroundO3 levels at the hemispheric scale, which showeda marked increase in the last decades, and about
45 per cent of global CH4 emissions occur in Asia2.

Effective air quality management mustalso address the growing threat ofground-level ozone

By 2030, in the absence of appropriate policy
interventions, population-weighted mean O3 in
2 For example, https://data.worldbank.org/indicator/
EN.ATM.METH.KT.CE?view=chart78

Thus, measures focused solely on PM2.5 do not
exploit the full mitigation potential for O3 precursor
emissions and might not be sufficient to bring
down O3 to levels that do not cause damage tohuman health, crops and ecosystems. In theinterests of a comprehensive clean air strategy, thisassessment also explores the additional benefitof extending the portfolio of measures to include
low-cost options for mitigating CH4 emissions.

A number of practical mitigation opportunities exist
in Asia for CH4 emissions (Table 2.7). While theinclusion of these measures in a comprehensive air
quality management portfolio is justified by concerns
about ground-level O3, it should be mentioned that a
reduction in CH4 emissions also forms an integral
part of SDG 13: Climate Action.

TABLE 2.6: KEY MEASURES CONTRIBUTING TO GROUND-LEVEL OZONE MITIGATION
Regional application of conventional measures
Post-combustion controls

Introduce state-of-the-art end-of-pipe measures to reduce
SO2, NOx and particulate emissions at power stations andin large-scale industry

Emissions standards for roadvehiclesStrengthen all emissions standards; special focus on
regulation of light- and heavy-duty diesel vehicles

Vehicle inspection andmaintenance

Enforce mandatory checks and repairs for vehicles

Next-stage air quality measures that are not yet major components of clean air policies in many
parts of Asia and the Pacific
Solvent use and refineries

Introduce low-solvent paints for industrial and do-it-yourself
applications; leak detection; incineration and recovery

TABLE 2.7: ADDITIONAL MEASURES AIMED AT GROUND-LEVEL OZONE WITH CO-BENEFITSFOR SUSTAINABLE DEVELOPMENT
Measures contributing to development priority goals with benefits for air quality
Solid waste management

Encourage centralized waste collection with source
separation and treatment, including gas utilization

Rice paddies

Encourage intermittent aeration of continuously
flooded paddies

Wastewater treatment

Introduce well managed two-stage treatment withbiogas recovery

Coal mining

Encourage pre-mining recovery of coal mine gas

Oil and gas production

Encourage recovery of associated petroleum gas;stop routine flaring; leakage control

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

79

Hydrofluorocarbon management
One final measure contributing to sustainable
development is the replacement of hydrofluorocarbon(HFC) refrigerants with environmentally friendly
alternatives through full ratification and compliancewith the Kigali Amendment to the Montreal
Protocol on Substances that Deplete the Ozone
Layer (Table 2.8).
Hydrofluorocarbons are a group of powerfulmanufactured greenhouse gases used primarily
as replacements for ozone-depleting substances
currently being phased out under the Montreal
Protocol, and are the fastest-growing group of
greenhouse gases in many countries due inpart to rapidly growing consumer refrigeration
and air conditioning markets. In addition to its
direct benefits, HFC mitigation can also catalyse
improvements in the energy efficiency of
the refrigerators, air conditioners and otherproducts and equipment that use HFC refrigerants,
which is a critical part of SDG 7: Affordable andClean Energy.

Implementation of the top 25 clean
air measures for Asia will achievesignificant improvements in air quality
Reductions in population exposure

road transport – offer the largest improvements.
Beyond these, key measures include access toclean cooking fuels, enhanced use of renewableenergy, control of forest fires and improved
agricultural practices (Figure 2.14).
Achieving air quality standards
Implementation of the top 25 clean air measures
could deliver, in 2030, air quality that conforms tocurrent national air quality criteria over large areasof Asia, but not everywhere. In particular, they will
not be sufficient in some megacities surrounded byindustrial areas, such as Beijing or Delhi, althougheven there additional local measures are likely tobring the standards within reach. In addition, PM2.5
levels will remain high in regions that are heavily
influenced by soil dust (Figure 2.15).
However, and most importantly, 1 billion people –22 per cent of the Asian population – will enjoy air
quality in line with the WHO Guideline, comparedto less than 8 per cent in 2015. Furthermore, thenumber of people exposed to pollution above thehighest WHO Interim Target level will decline by
80 per cent, from 2.3 billion in 2015 – 55 per centof the Asian population – to 430 million people,
leaving only 10 per cent exposed to such pollution
levels (Figure 2.16).

Implementation of the top 25 clean air measures
for Asia (Table 2.2) could bring mean population
exposure to PM2.5 down to about 20 µg/m3 in 2030
(Figure 2.13).
Overall, measures that are already widely appliedin Asia – especially post-combustion emission
controls in power plants and industry as well as for

TABLE 2.8: MEASURES WITH ADDITIONAL BENEFITS
Measures contributing to development priority goals with benefits for air quality
Hydrofluorocarbon (HFC)
refrigerant replacement

80

Ensure full compliance with the Kigali Amendment

Reduction in population exposure to PM2.5 in 2030 (μg/m3)
0
Cl
ea
n
Ind coo
us kinPo tria g
st- l prNi com oce
tro
bu ss
Re gen stio emi
ss
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Ag ion for pp
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Ve ent anu sidu ad nrehic iales vehicl
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Ric ast lic trinde p e m ans
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lac
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en
t

PM2.5 (μg/m3)
70

60
Avoided by already
implemented measures

50
Avoided by compliance with recent legislation

40
Potential from Asia-wide application of
conventional measures

WHO Interim Target 1

Potential from next-stage measures

30

10

0
Potential from development priority measures

20
Remaining anthropogenic sources

WHO Guideline

From natural sources

2015		

Already implemented measures
2030

FIGURE 2.13: CONTRIBUTIONS TO REDUCTIONS IN POPULATION-WEIGHTED
MEAN EXPOSURE TO PM2.5, 2015 AND 2030

-2

-4

-6

-8

-10

-12

Recent legislation

Further potential

FIGURE 2.14: IMPACTS ON POPULATION-WEIGHTED EXPOSURE TO PM2.5 IN 2030
OF 25 CLEAN AIR MEASURES FOR ASIA, RANKED BY FURTHER POTENTIAL

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

81

80
65
50
WHO Interim Target 1

PM2.5 (μg/m3)

105

35
25

WHO Guideline

15
10
0

FIGURE 2.15: PM2.5 CONCENTRATIONS IN ASIA IN 2030 AFTER
IMPLEMENTATION OF THE TOP 25 CLEAN AIR MEASURESTop 25clean airmeasures2030
Current
legislation
2030< WHO Guideline (10 μg/m3)< WHO Interim Target 1 (35 μg/m3)
35–50 μg/m3
50–65 μg/m3

2015
0

1

2

Billion people exposed to PM2.5

34

65–80 μg/m3> 80 μg/m3
People exposed to indoor pollution

FIGURE 2.16: POPULATION EXPOSURE TO PM2.5 IN 2015 AND IN 2030
FOR THE DIFFERENT POLICY SCENARIOSThe 25 measures will provide clean air to
1 billion people and reduce the number
facing exposure above the highest
WHO Interim Target by 80 per cent2.3.5 Health and other development benefits
The top 25 clean air measures for Asia identified inthis chapter not only improve air quality and reduce82

human exposure to air pollution, they also benefit
multiple sustainable development goals, including
the mitigation of climate forcers (Figure 2.17).
The measures represent a package of concrete
actions that simultaneously contribute to multiple
outcomes relevant to national development
priorities and their related SDGs, examples ofwhich are described in greater detail in Chapter 3.

The portfolios of conventional and next-stage
control measures are typically implemented forreasons of air quality, but also support othernational development objectives. Conversely,
the portfolio of measures aimed at national
development priorities,such as ensuring access toaffordable and clean energy (SDG 7), may not target
air quality per se, but do contribute to improving it.
While no single SDG focuses on air quality
specifically, it is addressed in the targets of threeof them:• SDG 3.9: to substantially reduce the number
		 of deaths and illnesses from hazardous
		 chemicals and air, water, and soil pollution
		 and contamination;• SDG 11.6: by 2030, reduce the adverse per		 person environmental impacts of cities, including
		 by paying special attention to air quality, municipal
		 and other waste management; and• SDG 12.4: by 2020, achieve the environmentally		 sound management of chemicals and all		wastes throughout their life cycle, in		accordance with agreed international
		 frameworks, and significantly reduce their		 release to air, water and soil in order to		 minimize their adverse impacts on human		 health and the environment.
Avoidance of premature deaths
Based on identical patterns of population exposure
to PM2.5, two different parametrizations of the healthimpact assessment methodology applied in the2010 and 2013 Global Burden of Disease studies
result, respectively, in 3.1 and 1.9 million cases ofpremature death in 2015. In the current legislation
baseline scenario, the health burden would increase
to 4.0 and 2.5 million cases by 2030, despite theslight downwards trend in population exposure. This
divergence is caused by (a) the population growththat is expected for this period, and (b) population

Population exposure
70

60

SDG
benefits

CO2

CH4

BC

Goal 3

+16%

+17%

-24%

Conventional measuresrelative to 2030 baseline

Goals 3, 15

0%

0%

-8%

30

Next-stage measuresrelative to 2030 baseline

Goals 2, 3, 15

0%

-29%

-56%

20

Development priority
measures relative to2030 baseline

Goals 2, 3, 5,
6, 7, 8, 9, 10,
11, 12, 13, 15

-19%

-44%

-72%

50
PM2.5 (μg/m3)

Climate forcers

40

10

0

Post-2015 legislation
relative to 2015

WHO Interim Target 1

WHO Guideline

CO2 - carbon dioxide CH4 - methane BC - black carbon
2015		

2030

Remaining anthropogenic sources

From natural sources

Already Implemented measures

FIGURE 2.17: IMPACTS OF THE TOP 25 CLEAN AIR MEASURESON POPULATION EXPOSURE TO PM2.5, EMISSIONS OF
CLIMATE FORCERS, AND OTHER SDG BENEFITSAIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

83

aging, which will increase the number of old people
who are more susceptible to air pollution.

in rural areas will use advanced biomass
cookstoves or replace coal with briquettes.

The top 25 clean air measures for Asia could leadto a 56 per cent lower PM2.5 exposure in 2030 thanin 2015. Premature mortality would then decline by
31–37 per cent, depending on the parametrizationof the health impact assessment method. Due tothe assumption of a flattening of the exposureresponse curve at high PM2.5 concentrations, healthimpacts decline at a lower rate than exposure.

This transition would cut the estimated number ofpremature deaths attributable to indoor pollution
by 1.2–2.0 million cases per year, depending on
the parametrization assumed for the health impact
calculations (Figure 2.19).

The top 25 clean air measures for Asia also deliver
substantial reductions in emissions of the O 3
precursor pollutants, NOx, VOCs, CO and CH4.
Using O 3 concentrations from two global
atmospheric chemistry-transport models, andapplying a health impact methodology usedpreviously to quantify O3 health impacts globally(Cohen et al. 2017; Anenberg et al. 2010), it wasestimated that 331,000 premature deaths from

5

50

4

40

3

30

2

20

1

10

0

Solid fuel users (billon people)

Premature deaths (million/year)

In addition, the top 25 clean air measures for Asia
will also lead to a drastic reduction in the numberof people using solid fuels (biomass and coal)for cooking purposes, from about 1.7 billion
people in 2015 to fewer than 0.4 billion people in
2030. This scenario assumes that while accessto clean cooking fuel will not be fully achieved
throughout Asia by 2030, the remaining population

Ozone-associated health impacts02015
WHO 2016

2030 withcurrent legislation
Sensitivity case (GBD 2010)

2030 with the
top 25 measures
Mean population exposure

Note: The WHO 2016 parametrization follows WHO GBD 2016; the sensitivity case draws on Burnett et al. (2014),
which is based on the GBD 2010 study.

FIGURE 2.18: PREMATURE DEATHS FROM EXPOSURE TO AMBIENT PM2.5, ESTIMATED
WITH DIFFERENT PARAMETRIZATIONS OF THE EXPOSURE-RESPONSE FUNCTIONS
Source: GAINS 201784

Despite uncertainties in quantifying O 3 healthimpacts due to relatively few studies in Asia, andrecent evidence in the United States of America
suggesting larger health effects than previously
reported (Turner et al. 2016), the implementationof measures focused on reducing PM 2.5
concentrations, in combination with measures toreduce CH4, would likely result in additional healthbenefits through reductions in O3 exposure.
Ozone-associated crop loss
In addition to the impacts of air pollution on humanhealth, ambient O3 concentrations can also damage
vegetation. This includes agricultural crops, resulting
in reduced crop yields (Ainsworth et al. 2012; Fengand Kobayashi 2009), as well as damage to naturalvegetation such as forests and grasslands (Wittig etal. 2009). Applying a methodology used previously toestimate O3-induced crop yield loss globally.

4

2.0

3

1.5

2

1.0

1

0.5

0

2015
WHO 2016

2030 withcurrent legislation
Sensitivity case (GBD 2010)

2030 with the
top 25 measures

Solid fuel users (billon people)

Premature deaths (million/year)

respiratory diseases were associated with O3
exposure in 2015 across Asia. The largest burden
was in South Asia, followed by East and Southeast
Asia and the High-income countries (Figure 2.20).
Under current emission control legislation, theestimated O3 health burden increases in all regions
by 2030, driven by a larger and older population as
well as changes in O3 concentrations. The top 25
clean air measures for Asia reduce this estimatedhealth burden by 40 per cent across Asia comparedto the 2030 current legislation projection. The
reduction in estimated O3 health impacts in 2030
under full implementation of the 25 measures islargest in Southeast Asia, at 58 per cent relative tothe 2030 current legislation scenario, followed by
the High-income countries (44 per cent), East Asia
(36 per cent) and South Asia (30 per cent). Thesebenefits are driven largely by reductionsin NOx and
VOCs as well as additional reductions in backgroundO3 from CH4 mitigation.

0.0

Mean population exposure

Note: The WHO 2016 parametrization follows WHO GBD 2016; the sensitivity case draws on Burnett et al. (2014),
which is based on the GBD 2010 study.

FIGURE 2.19: PREMATURE DEATHS FROM EXPOSURE TO INDOOR
PM2.5 POLLUTION, ESTIMATED WITH DIFFERENT PARAMETRIZATIONS
OF THE EXPOSURE-RESPONSE FUNCTIONS
Source: GAINS 2017

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

85

(Van Dingenen et al. 2009), crop loss resulting
from elevated O3 concentrations was estimated toreduce yields of maize, rice, soy and wheat acrossAsia by 10 per cent, 4 per cent, 22 per cent and 9
per cent, respectively, in 2015. This is equivalent toa reduction in crop yield of 51 million tonnes acrossall four crops, the majority of which is rice and wheat
loss. Only impacts due to elevated concentrationsof O3 are considered in this analysis; meteorologicalfactors and the impact of climate change or changes
in particulate matter are not included.
Implementation of the top 25 clean air measures
for Asia would reduce estimated O3-induced crop
loss by an average of 45 per cent compared to the2030 current legislation projection, equivalent to
20 million tonnes. The largest reductions would
occur in Southeast Asia (56 per cent reduction
in O3-induced crop loss), followed by East Asia
(48 per cent), modelled High-income countries(46 per cent), and South Asia (38 per cent).
Estimating O3 crop impacts is uncertain due todifferences in crop responses between Asia andother regions (Emberson et al. 2009), and because
these estimates do not include the impacts of O3
on all crops, or its impacts on forests and othernatural vegetation. However, the implementationof measures focused on reducing PM 2.5
concentrations, as well as measures targetingCH 4 emissions, are also likely to result in
substantial co-benefits to agricultural crop yields
through reductions in O3 concentrations.
Climate and temperature
While this report analyses policy measures fromthe perspective of protecting human health byproviding good air quality, the emission reductions
that emerge from the top 25 clean air measures
for Asia will also affect climate change in various

1000
900

Premature deaths (thousand/year)

800
700
600
500
400
300
200
100
0

2015 2030 2030
current withlegislation 25
clean
air
measures2015 2030 2030
current withlegislation 25
clean
air
measures2015 2030 2030
current withlegislation 25
clean
air
measures2015 2030 2030
current withlegislation 25
clean
air
measures2015 2030 2030
current withlegislation 25
clean
air
measures

Asia

East Asia

South Asia

Southeast Asia

High-income countries

Mean and 95 per cent confidence intervals derived using O3 concentrations from GISS and GEOS-Chem models

FIGURE 2.20: ESTIMATED NUMBER OF PREMATURE DEATHS ASSOCIATED WITHEXPOSURE TO O3 IN 2015 AND IN 2030 UNDERCURRENT LEGISLATION, AND WITH THE
TOP 25 CLEAN AIR MEASURES, ASIA-WIDE AND FOR THE MODELLED SUB-REGIONS

86

35

Yield loss (% total production)

30
25
20
15
10
5
0

2015 2030 2030
current withlegislation 25
clean
air
measures2015 2030 2030
current withlegislation 25
clean
air
measures2015 2030 2030
current withlegislation 25
clean
air
measures2015 2030 2030
current withlegislation 25
clean
air
measures

Rice

Soy

Wheat

Maize

Mean and 95 per cent confidence intervals derived using O3 concentrations from GISS and GEOS-Chem models

FIGURE 2.21: ESTIMATED O3-INDUCED CROP LOSS IN 2015 AND IN 2030 UNDER CURRENTLEGISLATION, AND WITH THE TOP 25 CLEAN AIR MEASURES FOR ASIA,
EXPRESSED AS A PERCENTAGE OF TOTAL CROP PRODUCTION

60000

Wheat

Ozone-induced yield loss (million tonens)

Soy
Rice
Maize

45000

30000

15000

0

2015 2030
2030
current withlegislation 25
clean
air
measures2015 2030
2030
current withlegislation 25
clean
air
measures2015 2030
2030
current withlegislation 25
clean
air
measures2015 2030
2030
current withlegislation 25
clean
air
measures2015 2030
2030
current withlegislation 25
clean
air
measures

Asia

East Asia

South Asia

South East Asia

High-income countries

Note: Mean estimates derived using O3 concentrations from GISS and GEOS-Chem models.

FIGURE 2.22: ESTIMATED O3-INDUCED CROP LOSS IN 2015 AND IN 2030 UNDER CURRENTLEGISLATION AND WITH THE TOP 25 CLEAN AIR MEASURES, EXPRESSED AS TONNES OF
CROP LOSS FOR FOUR STAPLE CROPS, ASIA-WIDE AND FOR THE MODELLED SUB-REGIONSAIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

87

ways. Air pollutants, such as certain aerosolsthat constitute PM2.5 as well as ground-level O3,
affect the radiative balance and influence
temperature increase, especially in the nearand medium terms. Different substances act
in different ways: some are warming (BC, CH4,CO), while others are cooling (SO2, NOx), with
regional impacts on temperature as well as on thetransport of heat over long distances – such as to
the Himalayas and the Arctic.

The measures will provide a net
reduction in the rate of global
temperature increase and significantly
contribute to a more sustainable lower
rate of warming
The analysis clearly demonstrates that any
meaningful move towards national andinternational air quality standards in Asia must
involve substantial reductions in the precursor
emissions of secondary PM2.5, (SO2, NOx, NH3 andVOCs). As, in general, these substances act ascooling agents, the reductions imply an increasein temperature due to the reduced cooling effect.
However, it is also clear that the portfolios ofemission control measures also affect emissions
with opposite features – those that contribute to atemperature increase.
Off-line calculations of the impact of Asianemissions scenarios on global mean temperatureusing the absolute global temperature potential(AGTP) (Annex 2.1) method suggest that thechanges in global emissions will result in an
increase in global mean temperature of about
0.6°C by 2050 relative to 2015. The top 25 clean
air measures applied in Asia could decrease thiswarming by about 0.31°C3 (Figure 2.23).
This net temperature change emerges from several
factors. By 2050, controls on the air pollutants SO2,
NOx, NH3, organic carbon (OC) and CO (but excludingBC) will cause a warming of 0.12°C (0.03–0.21). Thisis more than offset, however, by lower emissions of
the short-lived climate pollutants (SLCPs) CH4 andBC, reducing warming by 0.26°C (0.10–0.45), in
addition to the 0.04°C reduction in warming from
implementation of the Kigali Amendment by Asian
3 0.15–0.51 confidence interval for 67 per cent here and hereafter
based on climate sensitivity and forcing uncertainties

88

countries. Furthermore, the lower CO2 emissions
that emerge from the top 25 measures will reduce
temperature increase by 0.13°C(0.09–0.20). By
providing a net reduction in the rate of global
temperature increase, the top 25 clean air measures
will significantly contribute to the Paris Agreementtarget of a more sustainable lower rate of warming.
A comparison with the portfolios of conventionaland next-stage measures alone clearly highlightsthat the full set of top 25 clean air measures,
including the development measures, not only
results in larger health improvements, but at thesame time decelerates temperature increase. Bothalternative sets, which do not emphasize measures
to reduce CO2 and CH4 emissions, have little net
impact on temperature change, as the reductions
in warming substances (BC) just balance the cutsin cooling agents (SO2, NOx and OC).
Following the different implementation timelines
for the mitigation of the various climate forcers
as well as their delayed impacts on temperature
responses, the relative effects of the forcing
substances varies over time. While at the beginningof the time horizon the SLCPs deliver the largest
share (compensating the warming effects of the
reduction in air pollutants), the accompanying
mitigation of CO2 emissions gains importance inthe longer term (Figure 2.24).
While there are clear impacts on global mean
temperature, emission changes in Asia will also
affect temperature increase and precipitation within
Asia, although these changes are not uniform acrossthe region, nor are they all in the same direction(Figure 2.25). Calculations with the GISS Global
Climate Model (Annex 2.1) indicate particularly
significant changes in the ‘Third Pole’ area – theHimalayan and Tibetan Plateau. Furthermore,
there is substantial cooling in the high-albedo
regions of western parts of Asia, including partsof Afghanistan, Iran and Pakistan. Other parts ofAsia show increases, decreases or no change, butthese are not significant. This is not unusual for thehighly industrialized coal-using regions, where there
are significant sulphur (S) and NOx emissions and alarge reduction in those emissions in the mitigation
strategy that leads to local cooling.

0.2

Difference in temperature (ºC)

0.1

Other air pollutants

0.0

SLCPS (CH4+BC+HFCS)

-0.1

CO2
Net change-0.2

Mean and 95 per centconfidence intervals

-0.3
-0.4
-0.5
-0.6

Current
legislation

Conventional
measures+ Next-stage
measures+ Development
measures

SLCPS – short-lived climate pollutants
CH4 – methane
BC – black carbon
HFCs – hydrofluorocarbons
CO2 – carbon dioxide

Note: Other air pollutants include SO2, NOx, NH3, OC and CO.

FIGURE 2.23: CHANGES IN GLOBAL MEAN TEMPERATURE IN 2050
FROM THE THREE PORTFOLIOS OF MEASURES RELATIVE TO THE
CURRENT LEGISLATION BASELINE PROJECTION

0.2
0.1

Temperature change (ºC)

0.0

Other air pollutants

-0.1

SLCPs
(CH4+BC+HFCs)

-0.2

CO2
-0.3

Net change
Mean and 95 per cent-0.4

confidence intervals

-0.5
-0.6

2015

2020

2025

2030

2035

2040

2045

SLCPS – short-lived climate pollutants; CH4 – methane BC – black carbon
CO2 – carbon dioxide CO - carbon monoxide

2050

HFCs – hydrofluorocarbons

Note: Other air pollutants include SO2, NOx, NH3, OC and CO.

FIGURE 2.24: IMPACT OF THE DIFFERENT CLIMATE FORCERS ON GLOBAL MEANTEMPERATURE RESULTING FROM IMPLEMENTATION OF THE TOP 25 CLEAN AIR
MEASURES, COMPARED TO THE CURRENT LEGISLATION BASELINE, 2015–2050

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

89

°C-1.9 -0.36 -0.28 -0.2 -0.12 -0.04 0.04 0.12 0.2 0.28 0.36 0.51
Note: The stripes indicate significant changes (95 per cent confidence).

FIGURE 2.25: ANNUAL AVERAGE TEMPERATURE CHANGE
UNDER THE TOP 25 MEASURES RELATIVE TO THE CURRENTLEGISLATION BASELINE FOR THE YEARS 2046–2054
Source: GISS model, 2017

2.3.6. Implementation costs
The GAINS model estimates life-cycle costs foremission reductions, adopting a social planner’s
perspective focusing on the diversion of societal
resources, excluding transfer payments such as
taxes, subsidies and profits, and balancing up-front
investments with subsequent cost savings, forexample from lower energy use.
With such a perspective, it is estimated that Asia
currently spends about 1 per cent of its GDP(US$ 160 billion per year) on emission controls,with significant – although often hidden – benefits
for air quality and human well-being. By 2030,
while compensating for the additional pollutionthat will come from the 80 per cent enlarged
economic activity, full implementation of current
legislation will increase pollution control costs to
1.2 per cent of GDP. Full application of conventional
air quality measures across Asia would requireemission control costs of 1.55 per cent of GDP(Figure 2.26), and would reduce population
exposure by one third. At costs of 1.85 per centof GDP (about US$ 500 billion per year), inclusion of
the next-stage measures could reduce population
exposure by half.

90

While contributing to wealth andwell-being, implementation of
the top 25 clean air measures
for Asia requires only a small shareof the resources gained by future
economic growth
The full set of top 25 clean air measures for Asia
would cut population exposure by 60 per cent.
However, associated costs for air pollution controls
decline to approximately 1.5 per cent of GDP, due tothe lower consumption of polluting fuels reducing
the requirement for pollution control equipment.
Additional costs for implementing the measuresthat are primarily targeted at development priorities
are outside the scope of this air pollution-centred
assessment; however, it can be stated that thefull package of 25 measures would save about
US$ 75 billion per year on air pollution controls
in addition to delivering substantial air quality
benefits. Although air pollution control costs for allof Asia may seem high in absolute terms, at
US$ 300–600 billion per year in 2030, they constitutea rather small share of about 5 per cent of the
US$ 12 trillion per year increase in GDP envisaged
for Asia by 2030. Presently, the largest share ofpollution control costs is spent on technicallyadvanced emission controls for vehicles, and thisshare is expected to grow further along with theincreasing car fleet (Figure 2.27). Extension of theconventional pollution controls across all of Asia
would double costs in the power and industrial
sectors. The next-stage measures would direct
additional pollution controls to the residential andagricultural sectors, although the cost shares ofthese sectors would remain small in the overall
context, as many measures can be implemented
at low cost.

2.3.7 Tailoring approaches to Asia’s diversity

However, while the societal costs of somemeasures are low, economic actors (companies orhouseholds) might face high up-front investmentsthat will not be recovered within the short pay-backperspective of the private consumer, in contrast to
the longer time horizon that is suitable for social
planning purposes. Thereby, even if the societal
costs of some next-stage measures are low, theiradoption by low-income households and farmers
will present challenges. The same applies for someof the development measures, and strategies
to overcome these implementation barriers areactively sought in this context.

A clean air strategy will vary in approach according
to the context of each country and city, as well as
its capacity to develop and implement measures.
There is no uniform policy prescription for air
quality that is applicable to all cities, countries
and regions; such an approach would be neither
possible nor desirable for a problem that is sodiverse in local circumstances.

Strong economic growth in most of Asia,
especially after 2000, has been associated with
unprecedented increases in atmospheric pollution.
While in South and Southeast Asia most of the
precursor emissions of PM 2.5 continue along
historic growth paths, policy interventions have led
to a decoupling of emissions from economic
growth in the High-income countries and recently
in China (Figure 2.28).

2.0
1.8
1.6

Costs as % of GDP

1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0

2015

2030 undercurrent
legislation

2030 withconventional
measures

Already implemented measures2030 with
next-stage
measures2030 withtop
25 measures

Additional measures

Note: Costs for the development measures themselves are not included.

FIGURE 2.26: AIR POLLUTION CONTROL COSTS FOR 2015 AND
FOR THE DIFFERENT PORTFOLIOS OF MEASURES IN 2030
Source: GAINS 2017

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

91

Differing benefits
The impacts of the top 25 clean air measures on
air quality and population exposure differ acrossAsia. Population exposure would be brought
down to or below the WHO Guideline in Southeast
Asia and the High-income countries, and below
the WHO Interim Target level 1 in East and South
Asia (Figure 2.29).
As shown in Figure 2.30, the full package ofmeasures could eliminate exposure above the
WHO Interim Target level 1 in Southeast Asia andthe High-income countries, while in South Asia asmall percentage of the population would remain
exposed to PM2.5 above the highest WHO Interim
Target level 1.
Differing priorities
Obviously, each of the 25 measures offers different
potential air quality improvements, not only for all of
Asia but even more so for specific countries, owing
to the heterogeneities in social, economic,

technological and geo-physical conditions acrossthe region. Thus, any prioritization must take local
aspects into account and will deliver different
priority rankings.
Figures 2.31 to 2.34 list the impacts of theindividual measures taken in each of the four
sub-regions on mean population exposure withinthat sub-region. It should be noted that, due to thelong-range transport of PM2.5, exposure reductions
also occur outside each sub-region; however, tohighlight the immediate benefits from measures
within the sub-region, these additional reductions
are not included in the graphs.
East Asia
For East Asia, the priority measures that offer thelargest further potential to improve ambient air
quality differ markedly from the measures thatare currently applied and have already avoided
serious increases in pollution levels. While current
legislation is rather effective in controlling thecontributions from large industrial installations and600

US$ per year (billion)

500

400

300

200

100

0

2015

Power and heating

2030 undercurrent
legislation

2030 withconventional
measures2030 with
next-stage
measures2030 withtop
25 measures

Industry

Residential

Transport

Agriculture

Note: Costs for the development measures themselves are not included.

FIGURE 2.27: AIR POLLUTION CONTROL COSTS BY SECTOR, FOR 2015
AND FOR THE DIFFERENT PORTFOLIOS OF MEASURES IN 2030
Source: GAINS 201792

road vehicles (the darker segments in Figure 2.31),
in the future the largest additional improvements
emerge from clean cooking strategies to replacebiomass and coal, the control of agriculturalemissions from manure management and fertilizer
use, energy efficiency policies, and restrictions
on the open burning of agricultural and industrial
waste (the lightest segments in Figure 2.31).
South Asia
For South Asia, measures that are already
implemented (mainly controls for gasoline cars andsome industrial processes) will have a comparable
small impact on future air quality, while full and900

East Asia

500

400

Index (1990=100)

700

350

600

300

500

250

400

200

300

150

200

100

100

50

0

400

1990

1995

2000

2005

2010

2015

Southeast Asia

0

160

350

140

300

120

250

100

200

80

150

60

100

40

50

20

0

South Asia

450

800

Index (1990=100)

timely implementation of the recently decided
new legislation should deliver large benefits on
population exposure in the future. Beyond thesemeasures, the analysis confirms the predominant
importance of providing access to clean cooking.
Further improvements are offered by a wide
portfolio of measures, including full implementationof conventional emission controls for large
industrial and power facilities, enhanced
renewable energy, fertilizer use, the managementof agricultural residues and residential waste,inspection and maintenance of vehicles anddust controls.

1990

1995

2000

2005

2010

2015

0

GDP
1990

1995

2000

2005

2010

2015

High-income countries

SO2
NOx
PM2.5
NH3
VOCs

1990

1995

2000

2005

2010

2015

GDP – gross domestic product; SO2 – sulphur dioxide; NOx – nitrogen oxides; PM2.5 – particulate matter with an aerodynamic diameter
equal to or less than 2.5 micrometres (μm); NH3 – ammonia; VOCs – volatile organic compounds

FIGURE 2.28: THE EVOLUTION OF GDP AND OF THE PRECURSORS OF
PM2.5 IN THE FOUR MODELLED SUB-REGIONS OF ASIA, 1990–2015
Source: IEA WEO 2016; GAINS model estimates

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

93

80
70
60
PM2.5 (μg/m3)

50
40

WHO Interim Target 1

30
20
WHO Guideline

10

East Asia

South Asia

Southeast Asia

Avoided by already implemented measuresTop 25 measures
From natural sources

2030

2015

2030

2015

2030

2015

2030

2015

0

High-income countries

Avoided by compliance with current legislation
Remaining anthropogenic sources

FIGURE 2.29: CHANGES IN POPULATION-WEIGHTED EXPOSURE TO PM2.5 BETWEEN 2015
AND 2030, BY MODELLED SUB-REGION: THE BENEFITS OF IMPLEMENTING
THE TOP 25 CLEAN AIR MEASURES AND REMAINING EXPOSURE

East Asia

South Asia

Top 25clean airmeasures2030

Top 25clean airmeasures2030

Current
legislation
2030

Current
legislation
2030

2015

2015
0.0

0.5

1.0

1.5

0.0

Billion people exposed to PM2.5

1.0

1.5

2.0

Billion people exposed to PM2.5
High-income countries

Southeast Asia

Top 25clean airmeasures2030

0.5

Top 25clean airmeasures2030

Current
legislation
2030

Current
legislation
2030
2015

2015
0

100

200

300

400

500

600

700

3

50

100

150

Million people exposed to PM2.5

Million people exposed to PM2.5< WHO Guideline (10 μg/m )3< WHO Interim Target 1 (35 μg/m )035–50 μg/m3350–65 μg/m

65–80 μg/m
3> 80 μg/m

3People exposed toindoor pollution

FIGURE 2.30: NUMBERS OF PEOPLE EXPOSED TO DIFFERENT LEVELS OF PM2.5
IN AMBIENT AND INDOOR AIR, BY MODELLED SUB-REGION

94

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Reduction of population exposure in 2030 to PM2.5 (μg/m3)

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FIGURE 2.31: IMPACTS OF MEASURES TAKEN IN MODELLED EAST ASIA ON POPULATIONEXPOSURE TO PM2.5 WITHIN THE SUB-REGION, RANKED BY FURTHER POTENTIAL

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FIGURE 2.32: IMPACTS OF MEASURES TAKEN IN MODELLED SOUTH ASIA ON POPULATIONEXPOSURE TO PM2.5 WITHIN THE SUB-REGION, RANKED BY FURTHER POTENTIAL

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

95

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FIGURE 2.33: IMPACTS OF MEASURES TAKEN IN MODELLED SOUTHEAST ASIA
ON POPULATION EXPOSURE TO PM2.5 WITHIN THE SUB-REGION,
RANKED BY FURTHER POTENTIAL

-1

-2

-3

-4

-5

Further potential

FIGURE 2.34: IMPACTS OF MEASURES TAKEN IN THE MODELLED HIGH-INCOME
COUNTRIES ON POPULATION EXPOSURE TO PM2.5 WITHIN THE SUB-REGION,
RANKED BY FURTHER POTENTIAL

Southeast Asia
Compared to other sub-regions, current
policies in Southeast Asia, with their focus on
mobile sources, have delivered relatively small
improvements in overall air quality. In the future,clean cooking offers by far the largest potential
for further improvements, complemented by anextended application of the conventional pollution
control measures for large industrial sources.
However, measures in the agricultural sector
affecting manure management, open burning ofagricultural residues, forest fires and fertilizer use,
as well as additional policies for the transport
sector (inspection and maintenance, heavy- andlight-duty diesel vehicles), will also be
important (Figure 2.33).
High-income countries
As conventional emission controls are now
widely applied in the high-income countries ofAsia, further improvements in air quality requirea re-orientation towards sources that received
less attention in the past. In particular, control of
NH3 emissions, for example through improved
manure management, will be important to restrict
the formation of secondary particles. In addition,
further controls from international maritime
activities will deliver tangible benefits for air quality
in these countries, as well as numerous measuresthat contribute to the SDG targets (Figure 2.34).

2.4. CONCLUSIONS
Successful decoupling of pollution from
economic growth
In contrast to public perception, the policy actions
taken in Asia in the last decade have led to a clear
decoupling of SO2 and NOx emission trends from
economic growth, confirming world-wide experiencethat pollution controls do not prevent further
economic development. However, the actual benefitsof these policy interventions on air quality are lessvisible, as they are often outweighed by the steep
increase in economic activities.
Hypothetically, without the current policies,
population-weighted exposure to harmful

particulate matter would increase by about 50
per cent by 2030 given the envisaged economic
growth of 80 per cent. Thus, the current policiesdeliver clear and significant returns on air quality
and health benefits, even if they are not sufficient
to significantly improve the present situation.
Current efforts insufficient to meet air quality
standards
A full and timely implementation of the current
policies will lead to further reductions in SO2, NOx,
VOC and PM2.5 emissions despite the envisaged
further growth of the economy, although this will
not deliver the massive improvements in ambient
air quality that are required to meet national andinternational air quality standards. Among otherfactors, air quality benefits from these emission
reductions will be outweighed by a steady growthin agricultural emissions, which will enhance theformation of secondary particles.
Beyond the current focus
To move towards national and international air quality
standards, Asia will need to address those emission
sources that are not the focus of current air quality
management efforts in addition to safeguarding aneffective, Asia-wide implementation of conventionalemission control measures. In particular, controls ofagricultural emissions that act as PM2.5 precursors
will be essential. Controlling solvent emissions will
also be important to reduce population exposure
to PM2.5 as well as to ground-level O3. Together,
implementation of these measures could cut
current population exposure to PM2.5 in Asia by
about 50 per cent.
New priorities
Controlling NH 3 emissions from manure
management and fertilizer application, which
act as important PM2.5 precursors in ambient air,will be especially important. Proven measures
are available to reduce these emissions at low
cost, including the covered storage of manure,low-emission application of manure, reducing
over-fertilization and optimized application ofmineral fertilizers. Other priority measures relate
to small combustion sources, the open burning of

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

97

residential and agricultural waste, prevention offorest fires, effective inspection and maintenanceschemes for vehicles, and the reduction of road dust.
Complementary benefits from development
objectives
Actions that are prominently considered in thecontext of other development objectives, such as
for climate change, clean water and sanitation,access to clean energy, sustainable cities, or
responsible consumption and production, offer
further means of improving air quality in Asia. Even
if they are not primarily targeted on air pollution,
they eliminate, or at least reduce, some of the mostpolluting activities. However, such development
action alone, without targeted air quality measures,will not be sufficient to make progress towards air
quality criteria; dedicated air quality management
policies cannot be substituted by generaldevelopment policies.

levels. Further improvements require accelerationof clean cooking programmes, wider applicationof conventional pollution controls, and policies
that address other sources of pollution,
including fertilizer application, managementof agricultural residues and residential waste,enhanced renewable energy, effective inspection
and maintenance of vehicles and reduction ofroad dust.
Priority areas are similar in Southeast Asia, with theprevention of forest fires as an additional focus.
As conventional emission controls are now
widely applied in the High-income countries ofAsia, further improvements in air quality require
addressing agricultural sources such as manure
management, maritime shipping and action that
contributes to other development priorities.
A wide range of health and other development
benefits

Measures tailored for Asia’s diversity
A clean air strategy will vary in approach basedon the context of each country and city, as well as
its capacity to develop and implement measures.
There is no uniform policy prescription for air
quality that is applicable to all cities, countries andsub-regions; such an approach would be neither
possible nor desirable for a problem that is sodiverse in local circumstances.
In general, emission controls for agricultural
sources (manure, fertilizer, burning of residues,
forest fires) emerge as new priorities throughout
Asia, while the urgency of providing access toclean cooking fuel is reconfirmed by this analysis.
In East Asia, where most conventional air pollution
controls are already implemented at large scale, itwill be critical that air quality management widens
its current focus on large industrial sources andvehicles not only to agricultural sources, but also
to enhanced energy efficiency and renewableenergy policies.
In contrast, in South Asia effective implementationof recent pollution control legislation will be
indispensable for stabilization of current pollution

98

Despite uncertainties in the quantification of healthbenefits, the top 25 clean air measures could avoid
several hundred thousand cases of premature
death from ambient particulate matter pollution.
In addition, by providing clean cooking fuel for
1.3 billion people, they would avoid annually morethan a million premature deaths from indoor
pollution, predominantly among women and children.
Health impacts from exposure to ground-level O3
could be reduced by 35 per cent, and crop yield
losses by 45 per cent, equivalent to 20 million
tonnes per year.
In addition, measures that improve air quality andreduce exposure to air pollution directly contributeto multiple SDGs.
Contributions to the climate agenda
Due to the co-control of air pollutants, SLCPs andlong-lived greenhouse gases (CO2), the top 25
clean air measures could provide a net reductionin the rate of global temperature increase by about
one third of a degree Celsius in 2050, and thereby
significantly contribute to the Paris Agreementtarget of a more sustainable lower rate of warming.

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

99

CHAPTER

3

Closing theimplementation gap:
bringing clean air
to the region

3.1 INTRODUCTION

Millions of people in the Asia and Pacificregion could enjoy longer, healthier lives
if measures to control and prevent air
pollution were successfully implemented
Chapter 2 drew on the Greenhouse gas–Air pollution
Interactions and Synergies (GAINS) model and asuite of others to identify measures that could
significantly reduce air pollution in Asia andthe Pacific. The modelling shows that effective
implementation of 25 measures could prevent
exposure to dangerous levels of air pollution, while
avoiding premature deaths, increasing food security,and mitigating near- and long-term climate change
in the region. In achieving these benefits, the 25
measures could help the region make significant
progress towards meeting several Sustainable
Development Goals (SDGs), particularly SDGs 3, 11
and 13 (Elder and Zusman 2016).
Chapter 3 reviews broad trends and concrete
examples of implementation for the three setsof options making up the top 25 measures:conventional controls, next-stage measures anddevelopment priority measures. These threegroups of measures offer alternatives fromwhich countries can select nationally appropriate
options. Though the choice and timing of those

options will vary across the region, countries arelikely to go through a relatively similar process ofbuilding on increasingly robust science to informtheir selection. That process frequently begins
with environmental agencies acquiring initial air
quality monitoring data to identify and recognize
air pollution problems. This initial phase sets
the stage for improved monitoring data andemissions inventories that can contribute topolicies aimed at reducing emissions. Following
the development of inventories, analyses of theapportionment of emission sources will tend toform the basis for policies meant to enhance overall
air quality. A final stage will frequently consistof developing health-impact, cost-effectivenessand/or cost-benefit analyses to determine whichinterventions maximize the health and otherbenefits of clean air (Figure 3.1). Though thisreport presents regional results, national-level data
are available on request from the UN Environment
Asia and Pacific Regional Office to help decision
makers consider moving through this process.
This chapter is divided into four sections. In
section 3.2, it provides an overview of conventional
controls, demonstrating that national environmental
agencies have often worked with other agencies andindustries to introduce air quality standards andlegislation to implement these kinds of controls. It
then examines relevant next-stage and development

3. Reduce air pollution levels• Monitoring• Emission inventory• Source apportionment
2. Reduce emission levels

4. Reduce health impacts• Monitoring• Emission inventory• Source apportionment• Health impacts studies• Cost effectiveness analysis• Cost benefit analysis• Monitoring• Emission inventory

1. Identify and recognize problem• Monitoring

FIGURE 3.1: STRENGTHENING THE SCIENTIFIC BASIS FOR
AIR QUALITY MANAGEMENT OVER FOUR STAGES

102

priority measures in sections 3.3 and 3.4, highlighting
the diverse range of actors and institutions
involved in implementing these options. Section 3.5
summarizes some of the factors behind successful

implementation of the measures and reflects theimportance of multi-stakeholder governance andinnovative finance to improve compliance with themeasures in the region.

TABLE 3.1: THE TOP 25 CLEAN AIR MEASURES
Regional application of conventional measures
Post-combustion controls

Introduce state-of-the-art end-of-pipe measures to reduce
sulphur dioxide, nitrogen oxides and particulate emissionsat power stations and in large-scale industry

Industrial process emissions
standards

Introduce advanced emissions standards in industries, e.g.,iron and steel plants, cement factories, glass production,
chemical industry, etc.

Emissions standards for road vehicles

Strengthen all emissions standards; special focus on
regulation of light- and heavy-duty diesel vehicles

Vehicle inspection and maintenance

Enforce mandatory checks and repairs for vehicles

Dust control

Suppress construction and road dust; increase green areas

Next-stage air-quality measures that are not yet major components of clean-air policies in many
parts of Asia and the Pacific
Agricultural crop residues

Manage agricultural residues, including strict enforcementof bans on open burning

Residential waste burning

Strictly enforce bans on open burning of household waste

Prevention of forest and peatland
fires

Prevent forest and peatland fires through improved forest,
land and water management and fire prevention strategies

Livestock manure management

Introduce covered storage and efficient application ofmanures; encourage anaerobic digestion

Nitrogen fertilizer application

Establish efficient application; for urea also use urease
inhibitors and/or substitute with, for example, ammonium
nitrateBrick kilns

Improve efficiency and introduce emissions standards

International shipping

Require low-sulphur fuels and control of particulate
emissions

Solvent use and refineries

Introduce low-solvent paints for industrial and do-it-yourself
applications; leak detection; incineration and recovery

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS103

TABLE 3.1: THE TOP 25 CLEAN AIR MEASURES (contd.)
Measures contributing to development priority goals with benefits for air quality

104

Clean cooking and heating

Use clean fuels – electricity, natural gas, liquefied petroleumgas (LPG) in cities, and LPG and advanced biomass cooking
and heating stoves in rural areas; substitution of coal bybriquettes

Renewables for power generation

Use incentives to foster extended use of wind, solar andhydro power for electricity generation and phase out theleast efficient plants

Energy efficiency for households

Use incentives to improve the energy efficiency of household
appliances, buildings, lighting, heating and cooling;encourage rooftop solar installations

Energy efficiency standards forindustry

Introduce ambitious energy efficiency standards for industry

Electric vehicles

Promote the use of electric vehicles

Improved public transport

Encourage a shift from private passenger vehicles to public
transport

Solid waste management

Encourage centralized waste collection with source
separation and treatment, including gas utilization

Rice paddies

Encourage intermittent aeration of continuously flooded
paddiesWastewater treatment

Introduce well-managed two-stage treatment with biogas
recovery

Coal mining

Encourage pre-mining recovery of coal mine gas

Oil and gas production

Encourage recovery of associated petroleum gas; stoproutine flaring; improve leakage control

Hydrofluorocarbon(HFC) refrigerant replacement

Ensure full compliance with the Kigali Amendment

3.2 CONVENTIONAL EMISSION CONTROLS

Measures that are widely adopted in
the current emission control legislationof Asian countries will avoid a further
deterioration in air quality
One of the key findings in Chapter 2 is that, evenwith economic growth of about 80 per cent by
2030, the effective implementation of conventionalemission controls could maintain mean population
exposure to air pollution at the current levels andreduce exposure in some areas. For many countries
in Asia and the Pacific, ambient air quality andemissions standards are the starting point ofefforts to encourage power plants, industries andother sources to adopt these conventional controls.
When formulating standards, environmental
agencies across a growing number of countries
in Asia and the Pacific have become better atmaking the case for introducing and then tightening
standards. This is evident in both the increasing
overall number of countries adopting some level ofstandards and in the number of countries with themore stringent levels of standards (Figures 3.2 and
3.3). However, there is also scope for countries tobring standards in line with the criteria of the World
Health Organization (WHO).

PM10 (µg/m3)
> 89
80–89
70–79
60–69
50–59
Other
0

2

4

6

8

10

1995
2005
2015

Number of countries

FIGURE 3.2: NUMBER OF COUNTRIES WITH DIFFERENT LEVELSOF AMBIENT AIR QUALITY STANDARDS FOR PM10

PM2.5 (µg/m3)
40
35
25
15
0

1

2
Number of countries

3

4

2005
2010
2015

FIGURE 3.3: NUMBER OF COUNTRIES WITH DIFFERENT LEVELSOF AMBIENT AIR QUALITY STANDARDS FOR PM2.5
Source: Clean Air Asia 2016
AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

105

For energy and industrial sources, governments
have progressively tightened production andperformance standards and encouraged technicalor process changes to reduce emissions (UNESCAP
2001). In countries ranging from the Republic ofKorea to Thailand, these regulatory changes haveencouraged power plants to install flue gas
desulphurization and other emission control
technologies (Simacha 2015; Wang et al. 2014).
In some cases, the stiffening of regulations has
had an even greater effect. For instance, India
has recently moved towards energy-efficient
supercritical technologies due in part to the ongoing
implementation of increasingly stringent standards
for old and new coal-fired power plants (MoEFCC2015). In other instances, as occurred in India’s
capital of Delhi, phasing in stringent standards
has resulted in the shutdown of power plants or ashift to gas as the fuel of choice (Singh and Prasad2015). While tighter standards can encourage
investment in pollution control technologies or
broader structural change, there is often a need forlegally backed financial incentives that bring about
these shifts. In countries ranging from China to
Mongolia, legislation that provides for air pollution
fees has created those incentives (Clean Air Asia
2016a; Dasgupta et al. 2001).
The impacts of regulation can also be felt in certain
energy-intensive heavy industries. In fact, in somecases, regulations like those mentioned above
have helped stimulate investments in cleaner
technologies that have spread across the region.
Waste heat recovery (WHR) in China’s cement

sector is a case in point (Box 3.1). While significant
investments in pollution control and prevention
technologies could substantially improve air
quality (IEA 2016a), realizing the scalable gains
illustrated by China’s cement sector often requires
compliance incentives and clear evidence of costsavings that can encourage multiple industries toinvest in pollution control technologies (Liu 2015).

Many countries in the Asia and Pacificregion could adopt conventional controls
at early stages of their development
Clean air action plans are additional vehicles thatgovernments employ to control air pollution. In
some instances, these plans start with national
governments responding to emerging policy
priorities. In 2012, China’s national government
released new ambient air quality standards andtechnical regulations for an air quality index as partof a wide-ranging effort to curb fine particulatematter (PM2.5). That effort laid the foundation
for an Air Pollution Prevention and Control Plan
in 2013 that set sub-regional targets for PM2.5
reductions in Beijing-Tianjin-Hebei (25 per cent by
2017 compared to 2012), Yangtze River Delta (20per cent), and Pearl River Delta (15 per cent). Morerecently, India’s government adopted the National
Clean Air Programme (NCAP) that is, inter alia,
expanding the air monitoring network; improving
the dissemination of data and public outreach;and calling for plans for prevention, control andabatement of air pollution (MoEFCC 2018). In otherinstances, sub-national governments have been

BOX 3.1: WASTE HEAT RECOVERY IN NINGGUO, CHINA
In August 1995, China’s then National Planning Commission and Japan’s New Energy and Industrial
Technology Development Organization (NEDO) signed an agreement for a WHR power generation
demonstration project. That agreement led to work with Kawasaki Heavy Industry to install WHR at
the Ningguo cement plant of Conch Cement in 1998. Conch Cement took the lead in the diffusionof large-scale WHR after the success of the pilot project. Kawasaki Heavy Industry and Conch
Cement established three joint ventures over the period 2006–2009, and by the end of December
2016, a total of 279 clinker production lines based in 23 Chinese provinces and municipalities had
been equipped with 207 Conch-Kawasaki WHR systems. An additional 23 systems were set up in
37 clinker production lines in a further nine developing countries in Asia (Liu 2015).

106

behind important regulatory changes. Kawasaki,
Japan, introduced its own ‘total emission control
system’ (also known as the Kawasaki Method),which began with a city ordinance followed by the
implementation of more stringent environmental
quality standards and corresponding action (Clean
Air Asia 2016b). Clean air action plans do not always
start at the national level. Cities such as Can Tho,
Viet Nam, have also developed action plans to target
locally relevant sources (Bang et al. 2017).
The regulation of the transport sector, particularly
diesel engines, offers another conventional control
with potential benefits in the region. These gains
originate from more stringent vehicle emissions
standards. In many parts of the region, environmental
agencies have become more adept at working withtransport agencies, vehicle manufacturers andthe fossil fuel industry to make these standards
tighter. Cooperation with oil refineries is particularly
important since attaining stronger standards
requires lowering the sulphur concentration in diesel
fuel to 50 parts per million (ppm) and where possible
to 10 ppm. This is because some diesel control
technologies cannot function properly above theselevels. In the Philippines, the gradual tightening of
regulations motivated the Petron Corporation to begin
supplying 10 ppm gasoline in 2016 (Voltaire Palaña2016). Petron also recently announced the roll-out
of diesel fuels with a maximum sulphur content of
10 ppm in Malaysia (Petrol World 2016) – a significant

change as Malaysia currently supplies 500 ppm
sulphur diesel and gasoline.
Fuel switching, another solution to mobile source
pollution, has also been practised in some partsof Asia. Sometimes the impetus for regulatorychange comes from institutions outside government
agencies. India’s Supreme Court, for example, issued
a decision that required the entire Delhi public
transport fleet – buses, taxis and auto-rickshaws – toswitch to compressed natural gas (CNG) (Mehta
2001). There are currently 1,094 CNG stations inIndia due to this landmark decision (PNGRB 2018).
New technologies and actors have also become
important advocates for innovative reforms. The
International Council for Clean Transport (ICCT), aninternational non-profit organization that provides
research on environmental regulators, is working
with 20 megacities to introduce battery electric buses
as a low-cost soot-free option (Miller et al. 2017).
Non-technical solutions can help reduce emissions
from heavy-duty commercial vehicles. For example,
effective logistics and route planning for freightvehicles can avoid unnecessary travel and cut
emissions (UNCRD 2013). There can also be
effective combinations of measures – for instance,
replacing older buses can open an opportunity forroute rationalization and optimization that offers
complementary improvements in service quality.

BOX 3.2: TAXATION POLICIES AND HYBRID VEHICLES IN ULAANBAATAR
In total, 411,400 of the 675,000 vehicles in Mongolia are registered in Ulaanbaatar (Departmentof Traffic Police Ulaanbataar 2016). Many of these vehicles are older, second-hand cars imported
from Japan and Korea. A study from the Ulaanbaatar Transportation Department, for instance,found that 91 per cent of all vehicles on the road are from Japan and Korea. To reduce mobile
source emissions, Mongolia introduced an excise tax exemption and a reduction in taxes on theimport of hybrid, electric and LPG-fuelled vehicles in 2006. The existing excise tax amounts werebased on the vehicle’s year of production and engine size, with costs ranging from US$ 500
to US$ 5,000 per vehicle. In addition, all imported vehicles were required to pay import duty andvalue-added tax. The removal of the taxes led to a significant increase in low-emission vehicles
in Ulaanbaatar. Official figures indicate there were 74,437 hybrid and 11,981 LPG-fuelled cars in
Ulaanbaatar by end of 2016 (Statistical Agency of Ulaanbataar 2016).

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

107

For many developing countries in Asia and thePacific, much of the air pollution comes fromolder second-hand cars imported from developed
countries. To help reduce emissions from theseimported vehicles, Mongolia introduced an excise
tax policy favouring hybrid and electric vehicles
that has changed the second-hand car-purchasing
practices of low- and middle-income families. As
a result, the number of hybrid cars in the capital
Ulaanbaatar reached 74,437 at the end of 2016,
so that now 22 per cent of the city’s vehicles– including buses, trucks and special-purpose
vehicles – are hybrids (Statistical Agency of
Ulaanbataar 2016) (Box 3.2).
Apart from technical solutions, inspection andmaintenance (I&M) programmes that remove
the highest emitters are a critical component ofa well-designed diesel control strategy. In Tokyo,
Japan, a well-publicized and staffed effort toinspect vehicles helped remove the city’s highest
emitters. For the 13,000 buses in Jakarta, an I&M
programme reduced diesel soot by 30 per centand fuel consumption by 5 per cent (UNEP 2009).
A review of several programmes in Asia found thatthe following design features were important forsuccessful I&M:
• centralized I&M systems developed through		 multi-agency collaboration at the early stages
		 of planning, with a self-funding mechanism for		 regular audits of test centres;• comprehensive and recurrent fleet characterization		 to guide I&M policies and strategies;• timely and appropriate strengthening of I&M
		 policies and emissions standards based on		 the characteristics of the fleet and considering		 existing vehicle technologies, while advancing
		 towards cleaner emissions;• a strong vehicle maintenance and repair
		 service industry that is able to deal with		 vehicles that fail emissions testing;• consistent enforcement and reliable detection
		 technologies that build and maintain public
		 trust, awareness and participation;• complementary policies on vehicles that enter		 and exit the active fleets (Clean Air Asia 2016c).
Most conventional air quality controls are reinforced
by relevant legislation. For some countries in Asiaand the Pacific, legislation has become more
coherent as awareness of the adverse impacts of air
pollution has increased. In India, for example, several
sector-specific laws include provisions related to air
pollution. India’s Air Pollution Prevention and Control
Act of 1981 depends on the performance of its
Motor Vehicles Bill of 1988 (amended in 2007), theAuto Fuel Policy of 2002, the National Environment
Policy of 2006, and the National Green Tribunal Billof 2009 (from the National Environmental Tribunal
Act of 1995) (Clean Air Asia 2010).
Another set of conventional controls aims to reduce
fugitive dust from unpaved roads and infrastructuredevelopment. This dust is a serious air pollution
problem in areas with expanding transport andconstruction networks – for instance, some cities
in India attribute more than half of their PM2.5 tothis dust. It can also be a major issue in areas withquickly expanding transport networks and proximity
to high winds. In Mongolia, a phenomenon known

BOX 3.3: TOKYO METROPOLITAN GOVERNMENT DIESEL STRATEGY
An interesting example of a diesel control strategy can be found in Tokyo, Japan. In 1999, theTokyo Metropolitan Government established Operation No Diesel in response to growing publicconcern over air pollution. This was followed a year later by the promulgation of a new Ordinanceon Environmental Preservation that had as its centrepiece the Countermeasure Against Vehicle
Pollution programme. The countermeasure programme included diesel emission control
regulations requiring in-use diesel vehicles to be retrofitted with emission control systems or facea non-compliance travel ban in Tokyo. This was accompanied by a set of other measures thatwere designed to limit idling, prohibit heavy-oil fuels, and deploy vehicle pollution inspectors toremove high-emitting vehicles (Rutherford and Ortolano 2008).

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as silt-loading illustrates this problem: an increasein heavier vehicles that travel over greater distances
places stresses on unsealed road surfaces, creating
considerable emissions of particulates (Guttikunda
et al. 2013).
Several technical options are available to policy
makers to address these problems. Next to sealing
unpaved surfaces, water suppression that helps
gather dust to larger entities that are unlikely to be
re-suspended may be the most feasible near-term
option (Watson et al. 2000). Research in developed
countries has generated a range of chemical-based
road dust suppressants (Gillies et al. 1999). On
existing paved surfaces, pressurized sprays andstreet cleaning with mechanical equipment canvacuum or wash dust into drainage systems (Watson
et al. 2000). In some cases such as the city of
Rajhashi, Bangladesh, forward-looking politicians
and citizens have engaged in a concerted effort toplant more trees and shrubs to suppress the dust
(Graham-Harrison 2016).

3.3 NEXT-STAGE MEASURES
The implementation of conventional pollution
control and prevention programmes will help toprevent further deterioration in air quality despite
the 80 per cent economic growth anticipatedin Asia by 2030 (Chapter 2). Further measures,
however, will be required to reduce the healthimpacts of ambient air pollution that are alreadyapparent. In addition, conventional measures will
not address the impacts of indoor exposure to
air pollution.
This section focuses on a more diverse collectionof measures that goes beyond conventionalemission controls. Interventions range frommanaging agricultural residues sustainably toindustrial controls on solvents. Diversity is also
evident in the types of stakeholders involved incrafting and implementing next-stage controls.
3.3.1 Agricultural residues
Open burning involves the combustion of various
biomass materials such as crop residues (Marshallet al. 1996). It is a particularly large source of air
pollution in Southeast Asia, accounting for 5–30 per

cent of total anthropogenic emissions (Streets et al.
2003). Crop residue burning has strong seasonality.
It significantly increases PM2.5 concentrations in
the dry season and occasionally contributes to local
and regional pollution episodes (Kim Oanh 2013).
In Southeast Asia, burning is often carried out toclear land of crop residues in order to facilitate or
accelerate crop rotation (Kim Oanh 2013). It may also
be used to keep underbrush from encroaching onorchards or to clear land for cultivation. A majority of
wildfires, ranging from 50–95 per cent of all wildfires
according to national estimates, also originate fromopen burning in the agricultural sector. Burningin some countries, such as Nepal, has increased
in recent years due to societal change – asagricultural workers leave for salaried positions
overseas, less rural labour is available to gather
straw for animal bedding.
Measures to address the problem include bans on
open burning, though the effectiveness of institutingbans without engaging affected communities isquestionable and often counter-productive. Despite
the bans the burning continues, often with passive– but occasionally violent – farmer protests (Mohan2017). A potentially more effective set of measuresinvolves working with farmers to provide alternatives
to burning, such as low- or no-till conservation
agriculture. These methods, which involve planting
seeds directly through stubble, also bring adaptation
benefits such as increased resilience to extreme
weather – both drought and heavy rains – and adecreased need for fertilizer. The benefits accruing
from climate resilience and low fertilizer inputs leadto lower costs. In such cases, livestock manureand cover crops can also be used for soil enrichment.
Another no-burn alternative involves the on-farm orcommercial use of crop residues (Kim Oanh 2013)(Box 3.4). On-site microbial degradation may be
an effective way forward to avoid the burning ofcrop residues. The widespread use of mechanicalrice-straw baling machines can convert above-groundbiomass into compressed straw bales, help
farmers prepare land for the next crop cycle, andderive additional income from selling the bales(Kanokkanjana and Bridhikitti 2007). In India, thegovernment has taken a cross-sectoral approach,asking power companies to buy agricultural
waste from farmers and convert it into biomasspellets that can be co-fired with coal (PIB 2018).

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In addition, India is exploring the potential forbiomass gasification, the use of seed drills
that incorporate residues as a mulch (Happy
Seeders), and bio-methanation processes that put
agricultural residues to productive use and makeopen burning bans more effective. Off-site uses forcrop residues, such as the production of biogas forhousehold fuel or electricity generation, growing
mushrooms, brick production or use as silage or
animal bedding, can also offer win-win solutions.
3.3.2 Prevention of peat and forest fires
Forest fires are a long-running problem in Asia.
Many of the most serious fires are in Southeast Asia,
spread primarily by deliberate burning of agriculturalresidues and by aggressive land clearance that has
increased with the expansion of plantations forrubber, palm oil and paper production (Jerger 2014).
Economics are the main driver behind the burning:
clearing land mechanically can cost between 1.5 andat most 40 times as much as clearing land with fireand chemicals (Salim 2007) if the residue is not put tocommercial use.
Promoting no-burn methods in the agricultural
sector as a whole may decrease forest fires by up
to 90 per cent in some countries. In other cases,
where land clearance causes the majority offires, the creation of a market for useful products
may provide greater incentives to use no-burn

methods. These can be introduced independently
or with support for the purchase or lease of clearing
equipment, or through the outright monetizing ofconserved forest regions as carbon sinks.
Much of the effort to solve these problems has
focused on transnational and regional arrangements,
particularly the Association of Southeast Asian
Nations (ASEAN) Agreement on Transboundary Haze
Pollution (AATHP). Views on the agreement differ. To
some extent, it has helped give rise to collaborations
such as the Adopt-A-District programmes that saw
Malaysia and Singapore provide awareness-raisingand community-building support for the parts ofIndonesia where the fires originated. While these
efforts helped promote zero-burning practices andprovide communities with alternative livelihoods,
such as pineapple farming, they had a limited
effect on those industries that contributed
most to the burning (Quah and Varkkey 2007).
More recently, Indonesia’s decision to ratify theHaze Agreement has given rise to a Haze-freeRoadmap and greater enthusiasm over meansof implementation that would help support theprovisions in the roadmap (ASEAN 2017) (Box 3.5).
3.3.3 Manure management
Animal manure is a key source of ammonia, whichacts as an important component in the formationof secondary particles in the atmosphere. The

BOX 3.4: LIMITING OPEN BURNING IN THAILAND
In Thailand, open burning of crop residues is practised to prepare land for faster crop rotation.
Although the government has implemented bans on open burning and ‘stop forest fires’ campaigns
for several years, farmers continue burning because it offers an easy, inexpensive and quick way
to prepare for a new round of crops. Since most bans have been implemented without integrating
farmer education on the negative soil and crop-yield impacts of burning – such as increased
erosion and greater need for fertilizers – or support for viable no-burn alternatives, little progresshas been made. Thailand has therefore sought other approaches to help local governments halt
open burning. These include directly involving landowners, farmers and businesses in emission
controls through public relations activities, training, workshops and field visits. The government
has also promoted off-site use of agricultural residues through a business model that creates asustainable market for crop residues. Finally, the government has promoted technologies thatplough rice straw and corncobs into fields for on-site degradation.

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BOX 3.5: ROADMAP ON ASEAN COOPERATION TOWARDS TRANSBOUNDARY HAZE
POLLUTION CONTROL WITH MEANS OF IMPLEMENTATION (2016–2020)
Indonesia’s ratification of the ASEAN AATHP in September 2014 has helped to advance theagreement’s work programme. On 11 August 2016, the Roadmap on ASEAN Cooperation towards
Transboundary Haze Pollution Control with Means of Implementation (2016–2020) – the Haze-freeRoadmap – was adopted by the 12th Meeting of the Conference of the Parties to the AATHP.
The Haze-free Roadmap serves as a strategic, action-oriented and time-bound framework for the
implementation of collaborative action to control transboundary haze pollution in the ASEAN
region, aiming to achieve the vision of a Transboundary Haze-free ASEAN by 2020.
In recent years, the Haze Agreement has made significant progress as measured by the following
Haze-free Roadmap indicators:• an increase in the number of days with good or moderate air quality in terms of the Pollutant 				 Standard Index (PSI) or Air Quality Index (AQI), based on PM10 and/or PM2.5 concentrations;• a reduction in the number of hotspots below Alert Level 2 under the ASEAN Standard
		 Operating Procedure on haze;• a decrease in the transboundary haze pollution area.
Source: ASEAN 2017

proportion of total nitrogen (N) intake that is
excreted and partitioned between urine andfaeces depends on the type of animal, intake
of dry matter and N concentration of the diet.
About 80–95 per cent of ingested N is excreted
in dung and urine. As the N content of the dietincreases, so does the amount in the urine. Where
the ingestion of N compounds is high, more thanhalf of these compounds are excreted as urine(IPCC 1997).
Animal manure is not often managed in a systematicmanner in Asia and the Pacific. Most individual farmunits have small open pits where manure is dumped
and composted for later field application, while manyof the large industrial farms are decoupled from crop
production areas and therefore deal with manure as
waste rather than a resource in the form of organic
fertilizer. Among premium producers, however,
the emphasis on organic cultivation is prompting
farmers to manage animal manure scientificallyand thereby better meet the fertilizer requirementsof their crops. Improving manure management
practices, including the use of closed storage
tanks and rapid incorporation of manure into

soil following application, are effective means of
reducing ammonia losses.
3.3.4 More efficient fertilizer application
The use of chemical N-based fertilizers andagricultural productivity have both risen sharply
in Asia in the last four decades. At present, total
fertilizer nutrient consumption in Asia accounts
for 60 per cent of global use, with China and India
the largest producers and consumers of N-based
fertilizers (FAO 2014). Unfortunately, the use
efficiency of N-based fertilizers can be as low as
30–35 per cent, resulting in significant losses of
N compounds to the atmosphere and ecosystems.
Asia’s policy makers have become aware of theselosses and of the heavy subsidy burden, which has
been estimated at around US$ 7 billion for India
alone (Sutton et al. 2017).
National governments have adopted measures
to reduce the loss of N-based fertilizers whilecurbing environmental impacts and the financial
losses of subsidies. The government of India,
for example, introduced an initiative in 2015 that

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requires coating the entire urea-N production
with neem oil, a nitrification inhibitor that can
reduce the loss of urea by about 10–15 per cent.
Industry and research institutes in India havealso introduced the 4Rs Nutrient Stewardship
Programme – right form, rate, method and timeof application – to manage fertilizer N, to increase
its efficiency of use, matching fertiliser supply withcrop demand; minimizing N application in the wet
season to reduce leaching, and supplying fertilizers
to the plant rather than the soil. Other promisingtechniques – such as the split application of N,
slow- and controlled-release fertilizers, neem-coatedurea, speciality fertilizers and fertigation, and leaf
colour charts – could reduce India’s use of N-based
fertilizer use by 20–25 per cent by 2030.
These kinds of solutions have not been limited to
India. Bangladesh has introduced innovative waysof increasing the use efficiency of N-based fertilizers
with urea super granules, deep placement of urea,
bio-organic fertilizers and low-input crop varieties.
These measures have increased rice yield by 15–20
per cent and reduced the use of N-based fertilizers
by 20–30 per cent (Islam et al. 2016). Although
the adoption of urea super granules on a large
scale has encountered some application problems,
Bangladesh continues to promote this technology.
Sri Lanka is also adopting the 4Rs Stewardship
Programme to address low use efficiency and its
effects on groundwater contamination and air
pollution. Similarly, Pakistan is considering using new
fertilizer formulations, including inhibitors.

Small and medium-sized enterprises andinfrastructure development may requireinnovative management approaches toreduce emissions

new technologies. Perhaps the greatest variable indetermining the effectiveness of new technology
is the degree to which longstanding production
practices can be changed. Countries have sought
to change those practices through the phasingout of fixed chimney technologies (Bangladesh) or
sustainable building policy that aims to improve
efficiencies in brick production (Viet Nam). In
some instances, researchers and practitioners
have taken advantage of otherwise destructive
windows of opportunity to effect meaningfulchange. Following a major earthquake in Nepal in2015, for instance, a consortium of policy makers,
researchers and international development
specialists worked with kiln owners to introduce
more efficient technologies that have begun
to take hold in the areas around Kathmandu,
with growing interest in other countries in Asia
(Box 3.6) (Pradhan et al. 2018).
3.3.6 Shipping emissions
Control of shipping emissions is important to
air quality management and public health forcoastal port cities and regions with significant
marine traffic. Owing to concerns about port
competitiveness and trade opposition, port cities
in Asia and the Pacific have been slow to introduce
regulations on marine fuels. Indeed, a lack of
information about shipping emissions as a pollution
source has also hampered a better appreciation of
its implications for air pollution policy, evaluation of
the public health burden, and strategies to address
climate change. This is unfortunate because somestudies suggest that increased shipping emissions
lead to large adverse health impacts, including
15,000–38,000 premature deaths per year andclimate-related problems in East Asia (Liu et al.
2018; Fu et al. 2017).

3.3.5 Brick kilns
Brick kilns are a major source of air pollution in
many developing countries in Asia and the Pacific.
For countries suffering from their emissions, one
way to reduce the pollution involves shifting from
relatively energy-intensive fixed chimney kilns tomore efficient zig-zag, vertical shaft brick andtunnel kilns. The overall impact of these shifts
depends on the type of fuel and technology, andthe efficient operation and maintenance of the112

The Hong Kong Special Administrative Region
China (Hong Kong) has one of the top 10 international
container ports in the world and has been proactive
in reducing shipping emissions in the past decade.
The Ocean Going Vessels Fuel at Berth regulation,
implemented since July 2015 in Hong Kong,is the first marine fuel control regulation for
ocean-going vessels in Asia. The key part of thisregulation has been adopted nationally by China
for the establishment of three domestic emission

BOX 3.6: BRICK KILNS IN NEPAL
A sharp increase in demand for building materials followed the earthquake that struck Nepal in
2015. To respond to this growing demand in a manner that reduced the harmful environmental
and health impacts of brick kilns, the International Centre for Integrated Mountain Development(ICIMOD) collaborated with the Federation of Nepalese Brick Industry and MinErgy. The collaboration
resulted in a manual for induced draught and natural draught zig-zag kilns that proposed modestchanges to kiln design at a reasonable cost of about US$ 100,000 per kiln; free engineering
support and a pay-back period of less than two years helped to make those costs acceptable.
The nine newly designed kilns have delivered on their promise, effecting a 60 per cent decreasein particulate matter and a 40–50 per cent reduction in coal consumption, and increasing the
proportion of high-quality A-grade bricks to 90 per cent of production. Brick kiln entrepreneurs
from many parts of Nepal and other countries including Bangladesh, Pakistan and India are visiting
the new kilns with an eye to carrying forward some of the lessons learned (Pradhan et al. 2018).

control areas (DECAs) in its coastal waters thatwill come into force in 2019. The latest estimatessuggest that without control measures, bothsulphur dioxide (SO2) and particulate emissions
are expected to increase by 15–61 per cent in thethree DECAs in China between 2013 and 2020
(HKEPD 2011).
3.3.7 Solvents in industries and refineries
A set of industries that has received growing
attention over concerns about air pollution
emissions involves the production and use ofpaints, cosmetics, rubber and chemicals as well
as cleaning in industry and households. In someparts of Asia and the Pacific, the use of solvents isovertaking the transport and industrial sectors as
the largest source of volatile organic compounds(VOCs) (Wei et al. 2011). The sharp increase in theuse of these substances has led some to call fora greater effort to target solvents in air pollution
policies. Recent efforts have followed from thetargets in China’s 2013 Action Plan for Air Pollution
Prevention and Control (Box 3.7). Delhi’s governmentis aggressively pushing for the installation ofvapour recovery systems at petrol pumps to reduce
VOC emissions: by 2017, about 60 per cent ofstations had been fitted with systems that not only
reduce VOC emissions but save fuel. Illustratinga different regulatory style, Japan’s authorities
worked with industrial associations to design

voluntary programmes that led to declines in VOCemissions from several key industries (Matsumoto
et al. 2015).

3.4 DEVELOPMENT PRIORITY MEASURES
Although the implementation of conventional andnext-stage policies to prevent air pollution will
provide significant health benefits, the additional
development priority measures identified could
reduce population exposure to PM2.5 by up to 60
per cent by 2030 relative to 2015. One billion people,
about 22 per cent of Asia’s population, could enjoy
air quality that conforms to the WHO Guideline
for PM2.5 of 10 micrograms per cubic metre (µg/m3),
compared to only 8 per cent in 2015. Additionally,
the number of people exposed to pollution above
WHO’s first Interim Target, which is the highest
level, would decline by 80 per cent, from 2.3 billion
in 2015 to 430 million in 2030. The development
priority measures offer further means of improving
air quality, even if they are not primarily targeted at
air pollution. Often, they fall under the jurisdictionof different authorities in areas such as energy,
agriculture or transport.

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BOX 3.7: CONTROLLING EMISSIONS OF VOLATILE ORGANIC COMPOUNDS IN THE
BEIJING-TIANJIN-HEBEI REGION
In China, VOC control gained momentum when the 2013 Action Plan for Pollution Prevention andControl was adopted, mandating provinces to prepare local action plans. As part of the region withthe most stringent reduction targets, Hebei Province released their Action Plan Implementation
Scheme for 2013–2017. Also in 2013, the Ministry of Environmental Protection issued a VOC
Pollution Prevention Policy that required comprehensive control of VOCs in various industries. The
application of leak detection and repair (LDAR) systems in the petrochemical industry exemplified
one such response. A year later, the national government issued the Comprehensive VOC Control
Policy in Petrochemical Industry, requiring industries to achieve a 30 per cent reduction in VOCemissions by 2017 relative to 2014. Then in 2015, the government introduced VOC discharge fees
for the petrochemical, packaging and printing industries; Hebei Province and Beijing were amongthe 15 provinces and municipalities involved in the pilot. By the end of 2015, LDAR technology could
be found throughout the petrochemical industry and incentives for VOC control were instituted for
the Beijing-Tianjin-Hebei region. By 2017, Beijing successfully cut VOC emissions by 13,700 tonnes(exceeding their 13,500 tonne target), while Tianjin implemented online VOC emission monitoring of
19 key enterprises and 84 discharge outlets.

3.4.1 Clean cooking, heating and lighting

The implementation of measures
to control emissions from indoor
solid-fuel stoves, kerosene lamps
and heating is a development priority
for many countries
In several parts of Asia and the Pacific, residential
stoves burn firewood, animal dung and otherbiomass for heating and cooking, while inefficient
kerosene lamps often provide lighting inenergy-poor regions. The unevenness of the fuels’
combustion coupled with poor ventilation generates
indoor air pollution. About 64 per cent of the world’s
population cook with solid fuels and the stovescontribute to at least 1 million deaths per year.
Moreover, since seven of the top 10 populationgroups using solid fuels for cooking come from
Asia and the Pacific, the impacts tend to be
especially high in the region (WHO 2016). This isparticularly the case for women and children, who
spend more time near cooking environments(Rehfuess et al. 2006). Air quality and thermal
efficiency can both be improved by stoves thatuse LPG or electricity and those equipped with
fan-assisted technology – some of the numerous

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options across Asia, with an equally diverse rangeof performance. On balance, clean cookstoves cancontribute to achieving many of the SDGs (Box 3.8).
The country that has received the greatest attention
for its national cookstove programme is China.
From the late 1970s to the early 1990s, several
Chinese government agencies collaborated on
the National Improved Stove Program (NISP)
to bring cleaner stoves to 129 million households,
reaching approximately 65 per cent of China’s
population. The programme benefited from thesustained effort of the Ministry of Agriculture andthe discretion of other agencies to identify locally
relevant solutions. This flexibility allowed agencies
to start small and build to scale, and rural energy
companies to create markets for improved products(Sinton et al. 2004; Smith et al. 2003). In 2007, forexample, the Chinese government launched the
One Solar Cooker and One Biomass Stove Program
specifically in Tibetan regions and distributed
79,833 biomass stoves and 244,474 solar cookers
over four years (World Bank 2013). While the NISP
often gave the programme favorable reviews, others
have suggested it achieved little improvement
in indoor air quality, as other unimproved cookstoves
were often also present in the kitchen (Edwards

et al. 2007). China’s cookstove programme has more
recently undergone reforms, with new technologies,
better programme oversight and stronger links
to overarching development policies (Smith andDeng 2010). Starting in 2017, China’s government
mandated that residents replace coal stoves with
furnaces burning natural gas. As there was a
shortage in supply of natural gas, however, somefamilies were left without heating in the winter,suggesting the importance of allowing sufficient time
for the market to prepare for transition (Myers 2018).
India has also introduced several cookstove
programmes to help the approximately 100 million(out of 240 million) households that lack access tomodern cooking options. These efforts began with
the National Programme for Improved Chulhas(NPIC), a programme that in its most recent form,
known as the National Biomass Cookstoves
Initiative (NBCI), is focusing on developing andpromoting efficient (including fan-assisted),
cost-effective, durable and easy-to-use biomass
cookstoves. Other recent high-profile initiatives
include an ambitious scheme called Pradhan
Mantri Ujjwala Yojana. India’s Ministry of Petroleum
and Natural Gas launched this initiative in 2016 andhas facilitated access to 35 million LPG connectionsfor 100 million energy-poor households. The scheme
involves convening meetings or Ujjwala Panchayatsthat allow users to connect with each other,BOX 3.8: CLEAN COOKING AND THE SUSTAINABLE DEVELOPMENT GOALS
Clean cooking measures sit at the nexus of multiple SDGs. Ensuring access to clean and affordable
cooking can directly benefit SDG 1.1, which aims to halve extreme poverty by, for example, reducing
household expenditure on energy and the time spent collecting solid fuels. This also benefits
SDG 4 by ensuring that children have more time for education as well as fewer school days
missed due to air-pollution-related illness. This similarly impacts SDG 5.5 on ensuring women’s fulland effective participation and equal opportunities for leadership, and SGD 5.3 on reducing violenceagainst women. Clean cooking measures contribute directly to many health-related targets suchas SGD 3.9, by reducing deaths from air pollution, and SDGs 3.2 and 3.4, by reducing preventable
deaths among children under five years and premature mortality from non-communicablediseases. Many clean cooking solutions, such as expanding access to LPG, also contributeto SGD 7.1 on universal access to modern energy, SDG 11.1 on access to safe housing andupgrading slums, and to SDG 11.2, by reducing the environmental impact of cities. Reducing forest
degradation from fuelwood collection also contributes to SDG 8 by decoupling economic growthfrom environmental degradation, and to SDG 15.2 on the sustainable management of forests.
Measures addressing methane (CH4) emissions from agriculture, such as manure management
and intermittent aeration of rice paddies, can also promote multiple SDGs. Such measurescontribute directly to SDG 2.1 to double food production, and to SDGs 2.2 and 2.3 to end hunger
and malnutrition, by reducing the production of tropospheric ozone (O3) which can suppress
agricultural production and alter the nutritional value of some crops. Improvements in crop andforage production can also improve the economic livelihoods of farmers and herders, thereby
furthering SDG 1.1. Such measures can also contribute to SDG 2.4 by improving sustainableagricultural production. Manure management measures, which recover CH4 for further use,
contribute to SDG 7.1 on ensuring universal access to modern energy. This can support SDG 1.1
by providing a cost-effective source of renewable energy to poor farmers and herders, and SDG
8 by decoupling economic growth from environmental degradation. Reducing fugitive CH4
emissions in the agricultural sector also directly contributes to SDG 12.4, which aims to achieveenvironmentally sound management of all wastes.

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eliciting their concerns and experiences andsharing information on LPG use and safety. Other
smaller-scale activities in India have sought toextract indigenous knowledge and customize
cookstoves to user needs (World Bank 2011a).
Although the cases above focus on China andIndia, many other countries in Asia have accrued
useful experiences arriving at a cookstove
strategy (Box 3.9).
Programmes to reduce indoor sources of air pollution
have largely focused on replacing the stoves and fuels
used for cooking. However, in many places aroundthe world, wood, coal and other biomass are used forhome heating as well. In some developed countries,
residential wood-burning stoves are common andsubject to regulation and design guidelines, leading
to relatively low emissions. However, heating stoves
that burn coal are often used in places where coal
is readily available, such as China and Mongolia(Stoves Summit 2017), and are typically older,inefficient and unregulated, with the exception ofsome urban areas that have introduced bans on
the use of solid fuel for residential heating.

periods of time, such as overnight for heating,as well as for two or three discrete cooking events
per day. These stoves are also often used incolder climates and at higher elevations, in close
proximity to snow- and ice-covered regions. In theseareas, even lighter-coloured combustion particles
can reduce the reflectivity of the underlying surface,causing a warming influence on the climate. The
2017 Stoves Summit sponsored by the Climate andClean Air Coalition (CCAC), International Cryosphere
Climate Initiative, Global Alliance for Clean
Cookstoves and Poland’s Ministry of Environment,
identified several mitigation opportunities forcoal heating stoves and combined cooking andheating stoves. These solutions include emissions
standards, testing and labelling; ecolabelling;technology development towards advanced
low-emission stoves; fuel switching; district
heating; upgrading biofuels and transition to pellet
stoves; improving household energy efficiency;
separating cooking and heating appliances/
fuels; stove replacement programmes; policy andregulatory instruments; and financing options(Stoves Summit 2017).

Globally, many stoves that are now considered
cookstoves or heating stoves are actually used
for both purposes, especially in the winter or inhigh-latitude or high-altitude regions where there
is a greater need for space heating. Combined
cooking and heating stoves may be particularly
important since they are regularly used for long

BOX 3.9: CAMBODIA’S SUSTAINABLE GREEN FUEL ENTERPRISE
In common with many other countries in Asia, Cambodia has struggled with deforestation toprovide wood for highly polluting residential stoves. The Sustainable Green Fuel Enterprise(SGFE) programme was initiated to develop energy-efficient cooking solutions and curb harmfulenvironmental impacts. The SGFE is a private limited company that manufactures char-briquettes– made of 100 per cent recycled organic biomass waste – as a viable alternative to wood charcoal.
With support from a Global Alliance for Clean Cookstoves Pilot Innovation Fund grant, the SGFE hasgrown significantly, producing 40 tonnes of char-briquettes per month, and providing a sustainablesupply of clean fuel to approximately 500 households and small businesses. This growth is due
to many factors, including financial management assistance from a tax consulting company; a
new accounting system; improved gender relations and human resources management; in-kind
support to conduct a fuel life-cycle assessment; and improved supply-chain management.

116

3.4.2 Clean energyof renewable energy technologies along with
pollution abatement and strengthened monitoringand enforcement of emissions standards fordifferent sources (MoEF 2006). However, growth inclean energy consumption and energy efficiency
may also be due to reasons beyond proactive
national governments.

Policies that encourage the use ofrenewable energy and energy-efficienttechnologies can reduce energy
consumption and improve air quality
The adoption of policies that encourage theuse of renewable energy and energy-efficienttechnologies can reduce energy consumption andair pollution at the same time. Many countries in theregion have adopted promotional policies – fromrenewable portfolio standards to feed-in tariffs– that have contributed to declines in the costs
and increases in the consumption of solar andwind power (IEA 2016b) (Figure 3.4). The clearest
example is China, where solar power consumption
reached 28 terawatt hours (TWh) and wind power
consumption reached 55 TWh in 2016, respectively
constituting 36 per cent and 42 per cent of the
global totals for these sources of energy (BP 2017).
The declining costs and increased consumption ofsolar and wind power seem primed to continue inIndia, Indonesia, Japan, the Philippines, Thailand
and other parts of the region (BNEF 2017). Someof this progress is attributable to forward-looking
policies: India’s 2006 National Environment
Policy suggested an integrated approach,addressing energy conservation and the adoption

Solar

3.4.3 Energy efficiency standards – households
and industry
Energy efficiency standards for households
and industry often pay for themselves over the
lifetime of an investment. This potential has
been recognized by the Chinese government,
as illustrated by the inclusion of ambitious
energy efficiency targets in its 11th, 12th and 13thFive-Year Plans. China has also introduced anenergy efficiency programme that initially relied
on a series of training, auditing and better
reporting measures to improve energy efficiency
in the country’s 1,000 most energy-intensive
industries. This programme was later expanded toencompass the top 10,000 most energy-intensive
industries, with more responsibilities delegated to
sub-national provincial governments to support
training and reporting (Zhao et al. 2014).

Wind

70

250

60

China
India
Japan
Philippines
Republic of
Korea
Thailand200
Terawatt hours

Terawatt hours

50
40
30

150

100

20
50

10
0

0

2010 2011 2012 2013 2014 2015 20162010 2011 2012 2013 2014 2015 2016

FIGURE 3.4: TRENDS IN SOLAR- AND WIND-POWERED ELECTRICITY GENERATION
IN SELECTED COUNTRIES OF ASIA AND THE PACIFIC

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

117

India too has been proactive on energy efficiency.
Under the Energy Conservation Act 2001, India
established the Bureau of Energy Efficiency (BEE)to advance the energy conservation and efficiency
agenda through a variety of mechanisms. For
households, the BEE has implemented a labelling
programme for appliances to provide informed
choice to the consumer about a device’s energy
consumption. Labels are mandatory, so appliancessuch as air conditioners, for example, cannot besold without an approved energy information
label (BEE 2018).
Across Asia and the Pacific, there have also been
attempts to introduce pre-paid cards for energythat can raise household awareness of energy use
and motivate residents to purchase energy-efficient
appliances. In the Republic of Korea, for instance,
Seoul’s metropolitan government introduced avariety of demand-driven energy-saving measuresthat also improve urban air quality as part of the
One Less Nuclear Power Plant project (Lee et al.
2017; SMG 2017) (Box 3.10).
3.4.4 Improved public transport
Many developed countries in the Asia and Pacificregion have relatively well-developed public
transport systems that help reduce demand for
personal transport. Often these systems are mosteffective when combined with other measuresthat discourage the purchase of motor vehicles.
Singapore has received the most attention in thisregard owing to its carefully designed transportdemand-management strategy that charges cars
for entering key parts of the city. Even smaller
cities have enjoyed success in combining public
transport with urban planning (Rye 2016). The cityof Toyama, Japan, for example, sought to countera rising trend in residents moving outside the city.
To bring people back, the city invested considerable
effort in making the city more compact andintroducing a tram system that stops in its mixed
land-use areas (Takami and Hatoyama 2008).
3.4.5 Electric vehicles
China has been a global leader in the supply ofand demand for electric vehicles. This position ispartially attributable to a deliberate move by thegovernment to provide subsidies for the purchaseof electric vehicles and remove driving restrictions
based on licence plates in some cities (Du andOuyang 2017). The government of India is also
aggressively promoting the introduction of electricvehicles. Meanwhile, the city of Shimla has
introduced some electric buses for commercial
use. There have also been efforts in the private
sector, with Ola launching a pilot scheme in the cityof Nagpur to operate a multi-modal electric fleet(UITP-India 2018).

BOX 3.10: ENERGY – ONE LESS NUCLEAR POWER PLANT
Beginning in May 2012, the Seoul metropolitan government (SMG) introduced a project entitled One
Less Nuclear Power Plant that aimed to reduce annual energy consumption by 2 million tonnes ofoil equivalent – a reduction on a par with one nuclear power plant – by December 2014. The goal
was to be achieved through the development of energy-self-sufficient villages, solar photovoltaic(PV) power plants, a cooperative power plants project, car-sharing systems and other small-scaleinnovations. The SMG encouraged the private sector to establish installations for PV generation
as well as other fuel-cell and small-scale hydropower plants. The project owed its success todiverse groups of citizens actively participating in the implementation of community-basedenergy conservation programmes. The end result of this collaboration was that the project
reached its energy savings goal six months ahead of schedule and the average annual power
consumption of Seoul decreased by 1.4 per cent in 2013 in contrast to average increases of 1.76
per cent across the country.

Source: Lee et al. 2017; SMG 2017118

3.4.6 Solid waste management
The Asia and Pacific region is home to a diverse
range of waste management technologies andpractices, so it is virtually impossible to identify asingle solution. On balance, the region’s developed
countries tend to employ more advanced
technologies such as incineration with energy
recovery (waste-to-energy technology) andsystematic recycling of recyclable materials. In
contrast, developing countries tend to rely moreon direct landfill, often associated with open – andsometimes illegal – dumping and burning, andinformal recycling as well as environmentally soundintermediate treatment.
The cross-national differences in approaches towaste management appear at different juncturesin the waste stream, starting with the transportof waste. Advanced economies such as Australia,
Japan, the Republic of Korea and Singapore deploy
technology-oriented solutions for waste collection
and transport, including motorized vehicles,
compactors and transfer stations, along withsource separation and collection of recyclable
wastes. Emerging economies such as Indonesia,
Malaysia and Thailand also operate systematiccollection and transport of wastes, at least in large
cities, but collection of recyclables is still often
informal or through community-based approaches
such as waste banks.
Regional variations are also apparent in thetreatment of waste. Cambodia, for example,
has one engineered landfill site and 72 open
dumpsites. Singapore recycles 59 per cent of its
collected waste, of which it incinerates 39 per
cent. Meanwhile, sanitary or engineered landfill
treatment is commonplace in China and Japan.
Further, Japan relies heavily on incineration (oftenwith energy recovery) for intermediate treatment
to reduce waste volumes. Malaysia utilizes eightengineered landfill sites and 165 controlled
dumpsites. In Indonesia, more than 9 per centof collected waste is disposed of at engineered
landfill sites, almost 70 per cent by controlled
dumping, and 3 per cent by open dumping.
Recycling in developing economies is often
associated with large informal sectors. Althoughsome efforts promote recycling as government
policy, market-based and often informal recycling
is very common in Bangladesh, Cambodia, China,
India, Indonesia, Philippines and Thailand. Thus,
one way to promote systematic recycling in theregion is to collaborate with the informal sector.
Systematic efforts to promote recycling vary
greatly across the region: 83.4 per cent of all waste
is recycled in the Republic of Korea, whereas just
5 per cent is recycled in Malaysia. Due to higher
percentages of organic waste in the overall waste
mix in low- and middle-income countries and thegreater role of agriculture, the biological treatmentof waste, such as composting and anaerobic
digestion, is correspondingly more common. At thesame time, low-income countries generally have agreater need for waste management infrastructure,technology and financing.
For much of Asia and the Pacific, burning is arelatively easy and low-cost way to dispose ofwaste. The practice is common among householdswith limited access to waste management facilities
and also occurs in communities with rudimentary
landfill sites prone to spontaneous combustion.
Many parts of the region have introduced lawsthat forbid waste burning, imposing fines andpenalties on those caught doing it; the Philippines’
Ecological Solid Waste Management Act, forexample, includes such provisions. At the sametime, awareness and enforcement of legal
prohibitions are often limited or altogether lacking.
Not surprisingly, the most effective solutions tend
to combine technical measures with awarenessraising. To illustrate, Fiji has adopted a reduce, reuse,recycle awareness programme that has reduced
both the quantity of waste generated and the amountof burning. More generally, the Pacific islands
have begun to work together to develop regional
strategies to enhance waste management andreduce the need for burning (Isley and Taylor 2018).
3.4.7 Rice paddies
Anaerobic fermentation of organic matter in flooded
rice paddies generates CH4, a process that canbe interrupted by the drainage and intermittent
aeration of paddies during the growing season.
Many of Asia’s farmers have adopted the practiceto help save water and boost crop yields, achieving

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

119BOX 3.11: WASTE MANAGEMENT IN THE PACIFIC ISLANDS AND SMALL ISLANDDEVELOPING STATES
Because the Pacific islands and Small Island Developing States (SIDS) are highly dependent on
biological resources and ecosystems, managing waste is essential to safeguarding what are often
pristine environments. The Pacific islands and SIDS employ relatively similar approaches to waste
management. Regular waste collection services are concentrated in urban areas; reaching remoterural areas often presents a significant challenge. The SIDS rely chiefly on temporary dumpsites,
open or controlled dumps, and sanitary landfills for municipal solid waste disposal. General waste,often mixed with hazardous wastes including health-care waste, can be burned or buried at thedisposal site in the absence of incinerators. Waste picking and open burning is common, due, inpart, to the limited waste collection services. Many SIDS are exploring municipal waste-to-energy
options but would need enhanced capacity to properly manage the hazardous waste – such as
bottom ash, fly ash and flue gas – that can result from these processes (SPREP 2016).
The Pacific Regional Waste Management and Pollution Control Strategy 2016–2025 (Cleaner
Pacific 2025) is a comprehensive long-term strategy for the region to achieve sustainable waste
management and pollution prevention (SPREP 2016). Cleaner Pacific 2025 has three key elements:
addressing solid, liquid and hazardous wastes from varied sources, including disasters, asbestos,e-waste, health-care waste, used oil, trade, sewage and animals; chemicals management including
persistent organic pollutants (POPs), mercury and O3-depleting substances; and marine andterrestrial pollution control. Continuing support from regional projects and initiatives such as
PacWaste and J-PRISM complement the achievement of the Cleaner Pacific 2025 goals.
• Pacific Hazardous Waste Management Project – PacWaste Plus. Following on the achievements
		 of PacWaste, the 11th European Development Fund of the European Union has provided
		 another EUR 17 million to fund PacWaste Plus to support the implementation of Cleaner
		 Pacific 2025 in accord with similar regional initiatives. A four-year project amounting to EUR
		 7.85 million, PacWaste aimed to assist 14 Pacific islands and Timor Leste in managing
		 hazardous health-care waste, asbestos, e-waste and atoll waste. Some of its key outputs
		 include completing comprehensive regional baseline studies in 15 countries and 26 separate		 islands and improving physical structures and services for waste management, including
		 health-care waste incinerators, asbestos remediation, e-waste interventions and waste
		collection services.
•
		
		
		
		
		

Japanese Technical Cooperation Project for Promotion of Regional Initiative on Solid Waste
Management, Phase II (J-PRISM II). J-PRISM II supports the Cleaner Pacific 2025 strategic
goals with funding from the Japan International Cooperation Agency (JICA). Phase II will
focus on developing a monitoring mechanism for tracking the progress of solid waste
management. The project is running from February 2017 to 2022 in eight countries as well as
the Cook Islands, Nauru and Niue.

Source: SPREP 2017; SPREP 2016; Agamuthu and Heart 2014120

reductions in CH4 emissions as a desirable side
effect (Wassmann et al. 2009).
Due to a variety of successfully demonstrated
approaches in the region, the goal is frequently to
spread the word about successful options rather
than initiate new drainage schemes. In Japan,
farmers have adopted the practice of draining
their rice paddies for 10 days in the middle of thegrowing season to increase crop yields (Nagata
2010). China has experienced a more recent anddramatic embracing of drainage: between 1980
and 2000, the percentage of farmers using thepractice rose from approximately 25 per cent to 80
per cent (Li 2002). A system of rice intensificationthat incorporates intermittent drainage alongside
resource-conserving planting and soil and nutrient
management suggests that multiple elements
combined together may be useful for improved foodsecurity and CH4 emission reductions (Uphoff 2007).
3.4.8 Wastewater treatment
It is estimated that globally wastewater emitted
approximately 512 million tonnes of CH4 in 2010,accounting for approximately 7 per cent of total
CH4 emissions. Emissions from wastewater are
expected to grow by about 19 per cent between
2010 and 2030 (GMI 2013b).
Inadequate wastewater systems are a significant
cause of CH4 emissions in Asia and the Pacific.
As Asia’s population and economies continue togrow, the region’s demand for water will increasesignificantly. Accelerated urbanization andchanging consumption patterns, including diets
shifting towards highly water-intensive foods suchas meat, are also contributing to this increasing
demand (WWAP 2017).
Wastewater from human activities and agriculturaloperations and its overall pollution load will also
grow significantly in the region. Due to a lack ofwater infrastructure and technical, institutionaland financial capacity, especially in developing
countries, around 85–89 per cent of Asia’s domestic
wastewater is discharged directly into nearby
water bodies without treatment, causing severe
contamination to both surface and groundwater(Bao and Kuyama 2013). The need to deal

collectively with pollution caused by untreatedwastewater discharge is therefore urgent. At thesame time, in the face of growing water demand,
wastewater is gaining momentum as a reliable
resource, shifting the paradigm of wastewater
management from treatment and disposal to reuse
and recycling, and particularly to resource recovery– for example biogas (WWAP 2017).
In most developed countries, centralized aerobic
wastewater treatment systems are commonlyused to treat municipal wastewater. These systems
produce small amounts of CH4 emissions, but also
large amounts of biosolids that can significantly
increase the emissions. Meanwhile, in developing
countries with low rates of wastewater treatment,
the systems that do exist tend to be low-cost andless energy-intensive, utilizing the process ofanaerobic digestion of organic matter and resulting
in greater biogas emissions. This biogas, a provenand widely used source of energy in Asia, is a mixtureof CH4 (55–75 per cent) and carbon dioxide (CO2)(25–45 per cent) (Demirbas et al. 2016).
A number of proven technological approaches tomethane mitigation and recovery at wastewater
treatment plants have been applied successfully indeveloped countries (Table 3.2). Typical systems
include biogas digesters on a small and medium
scale, lagoon systems, medium- and large-scale
anaerobic digesters, septic tanks and other typeof latrines. Successful applications of anaerobic
digestion have been reported around the world,
including in Asia (GMI 2013b). The technology
is widely used in treating livestock manure andsewage sludge.
Although biogas is a clean and renewable energy
and considered an alternative to fossil fuels,
its dissemination is still limited and it is mainly
used by small-scale farmers in Asia and thePacific. One of the major constraints is a lackof financial attractiveness. Even top-rated
biogas-producing countries provide governmental
and non-governmental subsidies. Thus, in orderto ensure the sustainability of this technology,
existing policies should reform subsidies, motivate
investors with favourable financial conditions, andinvolve farmers early and often in local projects(Yousuf et al. 2017).

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121

TABLE 3.2: WASTEWATER MANAGEMENT SOLUTIONSTechnical options

Description

Installing anaerobic sludge
digesters (new construction
or retrofit of existing
aerobic treatment
systems)

Anaerobic digesters are used to process wastewater biosolids andproduce biogas, which can be used on site to offset the use of
conventional fuel that would otherwise be used to produce
electricity and thermal energy.

Installing biogas
capture systems at
existing open-air
anaerobic lagoons

Biogas capture systems for anaerobic lagoons are the simplest andeasiest method of harnessing wastewater biogas. Rather than investingin a new centralized aerobic treatment plant, covering an existing lagoon
and capturing the biogas can be the most economically feasible meansof reducing CH4 emissions.

Installing new centralized
aerobic treatment
facilities or covered
lagoons

Installing new centralized aerobic treatment systems or new covered
lagoons to treat wastewater in place of less-advanced decentralized
treatment options (or no treatment at all) can greatly reduce current andfuture CH4 emissions associated with wastewater. This option is mostviable in areas with expanding populations that have the infrastructureand energy available to support such systems.

Installing simple
degassing devices atthe effluent dischargeof anaerobic municipal
reactors

In several developing countries with warm climates (e.g., Brazil, India,
Mexico), anaerobic reactors fed directly with municipal wastewater –e.g., upflow anaerobic sludge blankets (UASBs), anaerobic filters, andfluidized or expanded bed, baffled reactors – are increasingly being used
for small- and medium-scale municipal wastewater treatment. In thesesystems, around 30 per cent of the CH4 produced is lost as dissolved
gas in the treated effluent. A closed column with enough turbulence rightafter the reactor can capture a significant amount of CH4, which may be
used beneficially or directed to a flare.

Optimizing existing
facilities/systems
that are not being
operated correctly andimplementing proper
operation andmaintenance

Optimizing existing facilities and wastewater systems that are not being
operated correctly to mitigate CH4 emissions is a viable alternative to
installing new facilities or wastewater treatment processes such asanaerobic digesters. Proper operation and maintenance also
ensure that facilities continue to operate efficiently, withminimal CH4 emissions.

3.4.9 Oil and gas
Methane emissions occur in all sectors of the oiland natural gas industry, from production throughprocessing to transmission, and result from normal
operations and routine maintenance as well as
fugitive leaks and system upsets.

122

As oil or gas moves through the system, emissions
occur through both intentional venting andunintentional leaks. Venting can occur throughequipment design or operational practices,such as the continuous bleed of gas frompneumatic devices that control gas flows, levels,
temperatures, and pressures in the equipment,
or from well completions during production.

In addition to vented emissions, CH4 losses canoccur from leaks (also referred to as fugitive
emissions) in all parts of the infrastructure, fromconnections between pipes and vessels, to valvesand equipment (US EPA 2017).
Methane emissions can also occur from the oil
industry as a result of:• field production operations: venting of associated		 gas from oil wells and storage tanks;• production-related equipment: gas dehydrators,
		 pig traps and pneumatic devices.
Numerous technologies exist to control emissions
and their costs have been summarized (US EPA
2017b). The potential of these technologies
is illustrated in Figure 3.5. Analyses of the top
10 opportunities to capture unintended andunnecessary CH4 emissions from oil and gas
production, including shale gas, show that they
could reduce CH4 emissions by more than 80
per cent and generate US$ 2 billion in additional
revenue for the industry in the United States eachyear (NRDC 2012). These technologies have huge
implications for global CH4 emission reductions.
The oil and gas industry understands the need toreduce CH4 emissions. In India, for example, aflare gas recovery system was installed to help
recycle and recover flare gases that are piped infrom Mumbai High offshore field (Emam 2015).
Meanwhile, Indonesia has adopted a zero flaring
policy as part of its climate change strategy(UKP4 2011). In 2017, eight of the world’s largest
oil and gas companies agreed to act to reduce
CH4 emissions, with BP, Total, ExxonMobil, RoyalDutch and four others agreeing to implement
guiding principles to minimize leaks from energy
infrastructure (Financial Times 2017).
3.4.10 Coal mining
Methane can be released into the atmosphere
during the process of mining coal. The amount of
CH4 released by this activity is predicted to increase
sharply in Asia and the Pacific due to enhanced
productivity of mining techniques and the extractionof more coal from deeper, gassier seams. Rather thanreleasing the CH4 into the atmosphere, it is possible
to capture and use it to generate energy, operateindustrial boilers, or for other productive purposes.
This can be accomplished with the installation ofdegasification systems that capture it. In somecases, enhanced degasification systems areneeded to capture CH4 that has been diluted withair (known as ventilated air CH4) to safeguard
against mine outbursts and explosions. While it
is common for mines in developed countries tohave recovery systems, the high upfront costs ofinvesting in the necessary technologies has made

13% Low-bleed or
no-bleed pneumatic
controllers
39% Green completions
and plunger lift systems

18% Leak monitoring
and repair
3% Vapourrecovery units

1% Triethylene glycol (TEG)
dehydrator emission
controls and desiccant dehydrators

2% Pipeline maintenanceand repair
12% Not addressedby technologies shown

9% Improved
compressor maintenance

3% Centrifugal
compressor dry seal systems

FIGURE 3.5: TECHNOLOGIES WITH THE GREATEST POTENTIAL TO REDUCE METHANEEMISSIONS IN THE OIL AND GAS INDUSTRY
Source: NRDC 2012

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

123

it less common in developing countries. About adecade ago, China began to use resources fromthe Clean Development Mechanism (CDM) to
overcome this barrier and facilitate the transfer ofrecovery technologies. Since then, it has adopted
several other domestic enabling policies that haveprovided regulatory and financial incentives, suchas tax relief, for investors in CH4 recovery projects(Karacan et al. 2011; US EPA 2009).
3.4.11 Hydrofluorocarbons
Reductions in energy use and pollution emissions
can be achieved with options that cut emissions ofhydrofluorocarbons (HFCs). One such set of options
involves retrofitting large and medium-sized facilities
with refrigeration and air conditioning systems
or other manufacturing processes that have low
global warming potential (GWP) (Carvalho et al.
2014). These changes are under way in Indonesia,
with a large group of Alfamidi convenience stores
having installed energy-saving refrigeration systems(Box 3.12). Yet another positive sign involves India’s
appliance manufacturer, Godrej & Boyce, which
leapfrogged high-GWP HFCs and went directly
to lower-GWP alternatives, selling more than
100,000 HC-290 room units with support from theGerman Development Agency and India’s Ministryof Environment (NRDC et al. 2014). As the majorityof Asia imports HFC products, policy makers andstandard-setting organizations need clear market
signals to avoid the accumulation and dumping of
HFC technologies. Japan’s Revised Fluorocarbons
Recovery and Destruction Law, enacted in 2013

and entering into force in 2015, offers a clear
signal with measures that require manufacturers to
dispose of gases as well as regulate the productsthat use them (Kumakura 2015).
3.4.12 Sub-regional priorities
As noted in Chapter 2, there are several measuresthat are not part of the top 25 measures at theregional level, but which could lead to significant
reductions in pollutant emissions in sub-regions orparticular countries. For instance, in Bangladesh
the government has identified rice-parboiling
units as an important source of air pollution andintroduced remedial measures to curb emissions.
3.4.13 Air pollution episodes
In response to episodes of high concentrations of air
pollution that attract considerable public attention,
governments in Asia and the Pacific are increasingly
aiming for short-term interventions that should either
reduce the severity of an envisaged pollution episodeor minimize the exposure of people to polluted air
during these episodes.
Most pollution episodes are caused by high emissions
across a large area upwind of cities and enhanced
by unfavourable meteorological conditions, including
low wind speeds and limited atmospheric mixing.
The emissions responsible for the pollution – PM2.5,
SO2 and nitrogen oxides (NOx), amongst others –remain in the atmosphere for about a week. Duringthat time, upwind emission sources contribute to

BOX 3.12: ENERGY-EFFICIENT REFRIGERATION IN INDONESIA
In an effort to conserve energy and reduce costs, Indonesia’s Alfamidi convenience stores, operated
by PT Midi Utama Indonesia, have, since 2014, introduced a CO2 refrigeration system as standard
for new stores. The new system’s energy efficiency was 18 per cent higher than that of theconventional HCFC-22 systems, lowering costs and contributing to environmental benefits. Powerconsumption data taken at three stores in Jakarta from 1 April 2014 to 31 March 2015 showed thestores’ average electricity saving to be 17,624 kilowatt hours (kWh) per year, corresponding to 12.9
tonnes of CO2 per year per store, compared with the estimated power consumption of HCFC-22
refrigeration systems of a similar capacity (UNEP and CCAC 2014). As of August 2015, Alfamidi
had installed CO2 refrigeration systems at a total of 912 stores across Indonesia.

124pollution in the target area. For a short-term action
plan to be effective, emission controls need to begin
about a week before the predicted event, and should
cover upwind sources over a distance of up to 1,000
kilometres due to the low wind speeds typical ofpollution episodes. Uncertainties about weather
forecasts extend the emission control area.
Many techniques have been adopted to manage
and mitigate the effects of these episodes. Some
focus on raising awareness of the severity of
air pollution and encouraging people who might
be especially vulnerable to stay indoors. Thiscan involve setting up alert systems and public
communication plans. Other methods focus on
temporary restrictions on vehicles and the haltingof construction. Many of the above approaches
were implemented in China following a series ofheavy pollution episodes that attracted policymaker attention in 2013 (Feng and Wenjie 2016).
In Southeast Asia, these episodes frequently havea transboundary character, which has led to efforts
to strengthen the ASEAN Transboundary Haze
Agreement (Box 3.5).
Short-term policy interventions have been
particularly successful in China, which has beenable to achieve emission reductions over very large
areas. In other cases, where governments have lesscapacity to impose temporary suspensions on awide enough range of economic activities over a
sufficiently large area, interventions have been lesssuccessful. In addition, given the disruptive natureof such interventions, the economic effectivenessof suspending activity remains questionable.
Long-term strategies that reduce emissions
from the most polluting activities in a plannedand scheduled manner are considered morecost-effective than policies that repeatedly require
the shut-down of entire production processes,
restrict the mobility of people and goods, or reducelabour productivity.

3.5 GOVERNANCE AND FINANCE

therefore need to tailor selected options to theirnational circumstances. In addition, there is no set
sequence a given country or community should
follow. Decision makers may want to place a greater
emphasis on agriculture then turn to industrial
sources; or they may concentrate on transport before
transitioning to fossil fuels. Though the priorities andtheir sequence are likely to vary from one country
to the next, one of this report’s main messages isthat decision makers should aim to strengthen thescientific basis for their solutions (Figure 3.1). In
so doing, they should be aware that all of the top
25 measures have been implemented with somelevel of success in the region. The solutions are
grounded in both science and experience.
The next logical question is what were the factors
behind the more successful experiences? Table
3.3 summarizes successful implementation anddescribes some important reasons behind it. Often,
the factor leading to exemplary action was growing
awareness of the magnitude and severity of air
pollution – which again underlines the importance ofbuilding a sound scientific basis for decisions. The
success factors also highlight the significant roleof enabling policies – from regulatory standards
to tax incentives – which created the conditions
that made it easier to introduce the measures.
Finally, the list of successful measures underlines
the crucial role of how different stakeholders in andbeyond the government introduced enabling policies,
financial incentives and other resources to make
implementation possible.
A persistent problem with environmental policies
is that what is written on paper is often not
implemented in practice, making a lack of compliancea significant hurdle to progress on air pollution
prevention and control in much of Asia and thePacific. Appropriate governance and financing
arrangements can help overcome that hurdle andclose longstanding implementation gaps. The next
section concentrates on the kinds of governance andfinancial arrangements that could help implement
a portfolio of different options.

The top 25 clean air measures for Asia and the Pacificoffer a menu of options for governments to consider
in their own national contexts. There is no uniformly
applicable set of solutions, and priorities will differ
across and within countries. Decision makers will

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125

TABLE 3.3 FACTORS ENABLING THE SUCCESS OF CLEAN AIR MEASURESIN ASIA AND THE PACIFIC

126

Regional application of conventional
measures

Relevant
experiences/case studies

Enabling/success factors

Post-combustion
controls

Introduce state-of-the-art
end-of-pipe measures toreduce sulphur dioxide,
nitrogen oxides andparticulate emissionsat power stations
and in large-scaleindustry

Thailand’s
installation of fluegas desulphurization
technologies

Tightening of standards
based on health impact
studies (WHO guidelines)that stimulate investment
in pollution control/cleaner
technologies

Industrial process
emissions standards

Introduce advanced
emissions standards inindustries, e.g., iron andsteel plants, cement
factories, glass
production, chemicalindustry, etc.

China’s adoption ofwaste heat recovery
technologies

Tightening of production,
performance and emissions
standards that stimulate
investment in pollution
control/cleaner technologies

Emissions standards
for road vehicles

Strengthening all
emissions standards;
special focus on
regulation of light- andheavy-duty diesel
vehiclesRegional tightening
and updating ofmobile-source
emissions standards

Collaboration between
environmental agencies,
transport agencies, oilcompanies and vehicle
manufacturers

Vehicle inspection
and maintenance

Enforce mandatory
checks and repairs
for vehicles

Tokyo’s (Japan)
diesel control
strategy

Centralized inspection
and maintenance systems
developed throughmulti-agency collaboration;
self-funding mechanism forregular audits at test centres

Dust control

Suppress construction
and road dust; increase
green areas

Bangladesh’s(Rajhashi)
tree-planting scheme

Forward-looking politician
and general public support

TABLE 3.3 FACTORS ENABLING THE SUCCESS OF CLEAN AIR MEASURESIN ASIA AND THE PACIFIC (contd.)
Next-stage air quality measures that are notyet major components of clean air policies inmany parts of Asia and the Pacific

Relevant
experiences/case studies

Enabling/success factors

Agricultural crop
residues

Manage agriculturalresidues including strict
enforcement of bans on
open burning

Thailand’s open
burning controls

Growing policy-maker and publicawareness of pollution sources/
impacts; complementing
burning bans with other use
options with the involvementof farmers, alternative off-siteuse of crop residues,
technologies that plough
residues into fields

Residential wasteburning

Strictly enforce bansof open burning ofhousehold waste

The Republic ofKorea’s waste
management
policies

Regulation on engineered
landfills and incineration;
collaboration with informal
sector for recycling

Prevention of forestand peatland fires

Prevent forest andpeatland fires throughimproved forest, land andwater management andfire prevention strategies

Indonesia’s
cooperation with
Malaysia/Singapore

ASEAN Agreement on
Transboundary Haze Pollution

Livestock manure
management

Introduce covered
storage and efficient
application of manures;
encourage anaerobic
digestion

China’s agricultural
policies

Combination of regulation, policy
and programmes for covering
compost; incorporating manure
into soil

Nitrogen fertilizer
application

Efficient application,urease inhibitors,
use of ammonium
nitrateBangladesh’s use of
urea super granules

Changing to modified ammonium
nitrate fertilizer; cost-benefit
analysis of the efficient
application of nitrogen fertilizer

Brick kilns

Improve efficiency andintroduce emissions
standards

Kathmandu’s(Nepal) shift frombull trench to
zig-zag kilns

Clear presentation of thebenefits of the retrofit;
collaboration with kiln owners
and technical experts inthe kiln redesign

International
shipping

Require low-sulphur fuels
and control of particulate
emissions

Hong Kong’s ruleson port emissions

Support from the International
Maritime Organization

Solvent use andrefineries

Introduce low-solvent
China’s volatile
paints for industrial andorganic compound
do-it-yourself applications; control policy
leak detection; incineration
and recovery

Growing public concern overparticulate pollution;
comprehensive reduction targets

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS127

TABLE 3.3 FACTORS ENABLING THE SUCCESS OF CLEAN AIR MEASURESIN ASIA AND THE PACIFIC (contd.)
Measures contributing to development
priority goals with benefits for air quality

Relevant
experiences/case studies

Enabling/success factors

Clean cooking andheating

Use clean fuels –electricity, natural gas,liquefied petroleum gas(LPG) in cities, and LPG
and advanced biomass
cooking and heating
stoves in rural areas;
substitution of coalby briquettes

China and India
cooking and heating
programmes

Growing policy-makerawareness of the impacts of
cooking on health; lessons
learned from the design ofprevious programmes

Renewables for
power generation

Use incentives to foster
extended use of wind,solar and hydro power forelectricity generation andphase out the least
efficient plants

China, India,
Indonesia, Japan,
Thailand, and thePhilippines’
renewable
programmes

Including renewable power
generation in energy andclimate policies; publicpressure to switch fromfossil fuels and nuclear
to renewables

Seoul’s (Republicof Korea) One Less
Nuclear Power Plant
project

128

Creation of bureau of energy
efficiency

Energy efficiency
standards forhouseholds

Use incentives to improveenergy efficiency ofhousehold appliances,buildings, lighting,heating and cooling;encourage roof-top
solar installations

India’s householdenergy programmes

Energy efficiency
standards forindustry

Introduce ambitious
energy efficiency
standards forindustry

China’s Five-YearDevelopment Plans

Including energy efficiency
targets in Five-Year Plans

Electric vehicles

Promote use of electricvehiclesMongolia’s excise
tax that favours
electric and hybrid
vehiclesPolicy that supports andpromotes the use ofelectric vehicles

Improved public
transport

Encourage a shift fromprivate passenger
vehicles to public
transport

Japan’s (Toyama)Compact City
Planning

Integration with Compact City
Planning

Solid waste
management

Encourage centralized
waste collection withsource separation andtreatment, including gas
utilization

Pacific islands andSmall Island
Developing States’
waste management

Regional waste management
policy and strategy

Australia’s rooftop
solar incentives

TABLE 3.3 FACTORS ENABLING THE SUCCESS OF CLEAN AIR MEASURESIN ASIA AND THE PACIFIC (contd.)
Measures contributing to development
priority goals with benefits for air quality

Relevant
experiences/case studies

Rice paddies

Encourage intermittent
aeration of continuously
flooded paddies

Viet Nam’s
Established tradition ofagricultural practices irrigation and drainage policy

Wastewater
treatment

Introduce well managed Japan’s treatment
two-stage treatment with technologies
biogas recovery

Coal mining

Encourage pre-mining
recovery of coal mine
gas

China’s methane
Use of existing economic
recovery programme incentives, tax; incentives,
well-defined gas property
rights unsubsidized free gas
market education andinformation dissemination

Oil and gas
production

Encourage recovery of
associated petroleum
gas; stop routine flaring;leakage control

India’s flare gas
recovery systems

Collective corporate action

Hydrofluorocarbon(HFC) refrigerant
replacement

Ensure full compliancewith the Kigali
AmendmentIndonesia’s HFC
reduction policies

Government mandate toshift to low-GWP coolants;
clear presentation of the costsavings from technology
changeEnabling/success factors

Promotion of decentralized
wastewater treatment units

BOX 3.13: SUSTAINABLE DEVELOPMENT GOALS 16 AND 17 AND AIR POLLUTION
In 2015, the international community agreed on the SDGs to help guide a development transformationin all countries through to 2030. Air pollution is mentioned in three of the 169 targets – 3.9 on
health; 11.6 on cities; and 12.4 on sustainable consumption and production – with many of theother SDGs also relevant to the drivers and impacts of air pollution (Elder and Zusman 2016).
Though not as explicit, SDGs 16 and 17, which focus on governance and means of implementation,
include many targets that could help improve air quality management. For SDG 16, these range
from 16.3 on the rule of law to 16.6 on effective, accountable and transparent institutions. For SDG
17, they range from 17.1 on strengthening domestic resource mobilization to 17.7 on promoting
the development and transfer to developing countries of environmentally sound technologies.

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129

Multi-stakeholder partnerships canhelp improve compliance, deliveringcleaner air and other benefits to
Asia and the Pacific3.5.1 Government agencies
The term governance refers to the exercise of
authority in the pursuit of publicly desirable goals.
The performance of national and local agencies ispivotal to successfully governing air pollution. As
such, it is important to consider which authorities
have the responsibility to govern – that is to rule andto control air quality and pollution. The existenceof institutional capacity in terms of personnel
and knowledge, paired with a clear political andlegal mandate, are crucial for the successful
implementation and control of air quality measures,and ultimately to establishing a link to further
commitments at the international level, suchas the SDGs.
Most countries in Asia and the Pacific haveestablished air quality management agencies ordivisions in environmental agencies. In Thailand, forexample, the Pollution Control Department (PCD),
founded in 1992 under the Ministry of Natural
Resources and Environment, has the responsibility
for preventing and controlling air pollution under
the Enhancement and Conservation of National
Environmental Quality Act (1992) (PCD n.d.). Many ofthese agencies have seen their staffing and budgets
grow in recent years. For example, the number of
employees working in sub-national environmental
protection bureaus in China doubled between 1998
and 2014. These are promising trends that will needto continue – and be considerably strengthened formany countries – to achieve the goals presented inthis report.
A concern closely related to capacity is whether
environmental agencies have the de facto authority
to regulate emission sources. Though environmental
agencies have seen their status rise across Asia,
they may struggle if more powerful agencies
have conflicting objectives (Li 2006). Fortunately,
however, there are also signs of changing agency
power dynamics. The growing awareness of theadverse impacts of air pollution, for example, led
to important institutional reforms in China. In

1302015, China’s government introduced a verticalmanagement system at the Fifth Plenary Sessionof the 18th Central Committee Conference tohelp address several institutional issues that
previously hampered compliance with air pollution
regulations and policies.
Coordination across and within agencies is also
becoming more essential. This is particularly
the case because more integrated air pollution
and climate change policies will require steadilystrengthening coordination across government
agencies to improve air quality, mitigate climatechange and yield a range of other benefits. Examplesof improved coordination include the decision
for China’s newly-created Ministry of Ecology
and Environment (MEE) to absorb functions thatwere originally under other ministries, particularly
climate change and emission reduction policies.
Another illustration is the inclusion of air pollution
in nationally determined contributions (NDCs) thathave been pledged to the United Nations Framework
Convention on Climate Change (UNFCCC).
Other considerations involve the devolution of
authority to sub-national governments. Overthe past two decades, governance has become
multi-tiered or polycentric with power increasingly
shared among different stakeholders outside
central government (Andersson and Ostrom 2008;
Bulkeley and Betsill 2005). Reflecting this redistributionof authority, cities have been delegated many new
responsibilities over air pollution. While devolution
or vertical integration can be problematic if local
governments are lax or lack capacity, sub-national
governments can also be an important source ofinnovation. This is clearly evident in the reforms
to public transport and urban planning foundthroughout Asia and the Pacific. In some cases,
central governments can encourage these
innovations through fiscal policies that transfer
resources or grants to help local governments
finance new solutions to air pollution.
3.5.2 Civil society and the general public
Civil society and the general public are an increasingly
important source of support for environmental
policies and measures. Environmental movementsthat helped spur institutional change in developedcountries during the 1970s have become notably
more influential in advancing new approaches
to environmental management in developing
countries over the past two decades (Yang andCalhoun 2007; Mertig and Dunlap 2001; Mertig andDunlap 1995; Dunlap and Mertig 1992). Countries
are also setting up institutional channels allowing
civil society organizations and the general public
to articulate concerns about pollution (Jodoin etal. 2015). For example, Greenpeace East Asia is
working actively from Beijing, Hong Kong, Seoul
and Taipei in combating pollution and climatechange (Greenpeace East Asia 2012). Recently,
some governments also seek to improve thedialogue with societal groups and the general publicby creating institutional channels through which
concerns about pollution can be shared (Jodoin
et al. 2015). In China, for example, public concerns
can be articulated through complaint letters sent
to environmental protection bureaus. Civil society
organizations can also play an important role inmonitoring pollution, serving as an early warning
system that enhances capacities to monitor pollution
sources (Cohen 1998). Thailand’s Pollution Control
Department, to cite another case, often inspects
pollution sources based on citizens’ complaints(AECEN 2004). A third case is the Philippines’ creationof multipartite monitoring teams made up of a variety
of stakeholders that help the government monitor
projects (Environmental Management Bureau n.d.).
In some countries, notably Pacific island nations,community leaders outside formal government
may have more influence on the behaviour ofresidents. Giving community leaders authority to
enforce some directives, such as bans on burning
domestic waste, agricultural waste or forests,
has been more effective in Fiji than government
directives (Isley and Taylor 2018).
Reliable, accurate and timely monitoring data –though not strictly an actor that exercises authority– can help improve compliance and strengthen
regulatory authority. Most air quality monitoring
stations measure PM10, PM2.5 and total suspended
particulates. Coverage is typically more extensive
in developed countries or the capital cities ofdeveloping ones. Most large cities in Japan, theRepublic of Korea, Singapore and Thailand observe
stringent monitoring procedures, but many other

cities confront limits on equipment, monitoringand siting procedures, and quality assurance andcontrol procedures (World Bank 2011b). India hasrecently made significant efforts to improve its
National Air Quality Monitoring Programme (NAMP)– which began in 1984 and consists of close to
700 stations covering approximately 300 cities
and towns. Additional finance can help improvemonitoring in India and elsewhere, but careful
thought is needed to ensure the sustainabilityof funding as aid-driven air quality monitoring
programmes can cease operations once funding
runs out (ADB and Clean Air Asia 2014).
3.5.3 Funding
One of the main reasons behind gaps in compliance isthe lack of financial resources for pollution prevention
and control. Most countries in Asia allocate
financial resources for environmental management
as part of annual nationally appropriated funds.
One way to boost those outlays is to ensure thaturban planning prioritizes air pollution control
measures – and hence the allocation of funds forthe enforcement of such measures at the local
level. Private-public partnerships can help support
cleaner infrastructure. Special funds to finance air
pollution control projects may also be establishedby governments. The Philippines set up the Special
Vehicle Pollution Control Fund (SVPCF) as a seedfund to support emission reduction initiatives inthe transport sector. Funds are generated froma charge on all motor vehicles, paid by the owner(Napalang et al. 2016).
The private sector, particularly financial institutions,can complement government efforts by supporting
investments that reduce air pollutants (UNESCAP
2016). Several of the top 25 measures are consistent
with national development priorities and could be
supported from public funds. At the same time,
the private sector and businesses can help fundcleaner technologies, provided a favourable enabling
environment is in place. Currently, there are also
a number of innovative instruments available tofinance green projects (Box 3.15). Green bonds,
which are estimated to increase to US$ 100 billion in
2018, can be a major source of finance. Commercial
banks can be required to lend a certain percentageof their investment portfolio for green projects. This

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131

BOX 3.14: TROPICAL LANDSCAPES FINANCE FACILITY – LEVERAGING PUBLIC FINANCE
TO SUPPORT GREEN GROWTH
In line with the SDGs and the Paris Climate Agreement, the Indonesian government, together
with UN Environment, the World Agroforestry Centre (ICRAF), BNP Paribas, and ADM Capital,
officially launched the Tropical Landscapes Finance Facility (TLFF) on 26 October 2016. The
TLFF, as the first private-sector landscape financing facility at scale, aims to pool financial
resources for supporting sustainable agriculture and land management, renewable energy,
and overall rural livelihoods. The TLFF mobilizes capital through its loan and grant funds. The
TLFF Loan Fund seeks to provide long-term loans of at least 10 years’ duaration to projects thatcomply with zero deforestation criteria and environmental, social and governance standards.
The work to be undertaken by the TLFF Grant Fund focuses on capacity building of farmers andrural communities, land rehabilitation, and the availability of renewable energy in rural areas. This
component provides an opportunity for institutions and philanthropic foundations to contribute togreen growth and sustainable development in Indonesia.

Tropical Landscapes Finance Facility Operational Framework

TropicalLandscapes
Finance Facility(TLFF) Steering
Committee

Institutional
Investors

Bonds
sold toInvestors

TropicalLandscapes
Bond (TLB)

Structures
Loans into
Bonds

Credit Facility(Managed by
BNP Paribas)

Reports

Invesment
Advisory
Board

Supports

TLFF
Secretariat(Supported by
UNEP/ICRAF)

Supports

Reports

Reports

US$ 1-5 Billion
Loan Fund (TLLF)(Managed by
ADM Capital)

US$ 100 Million
Grant Fund (TLGF)(Managed by a
UN Entity)
Technical
support andLong-term
Loans

Energy Accessto RuralHouseholds

Source: TLFF 2017132

GrantsAdvisory
Board

Land
Restoration

Renewable
EnergySustainable
Agriculture

Donors:Philanthropic
Organisations

strategy was successfully implemented in Fiji, andeven exceeded its targets (UNESCAP 2016). For
some of the top 25 measures, it may also be possiblefor development banks working in the region toemploy these instruments to help overcome suchbarriers as high upfront costs. In a similar way,development banks may consider aligning theirstrategies with some of the top 25 measures. Last
but not least, there may be growing opportunities totap climate finance mechanisms such as the Green
Climate Fund for activities that prevent air pollution
in mitigating greenhouse gases.
A final set of factors involves the role of businessand industry. Polluting industries can assist or
prevent changes in the design and implementation ofregulations, particularly if they work with regulatory
agencies who seek to change pollution-intensive
development patterns. At the same time, businesses
are recognizing the advantage of taking action
to preserve the environment and investing in newenergy and cleaner production technologies (Kingand Lenox 2002; Maynard and Shortle 2001; Wheeler
2000; Gunningham and Rees 1997; Porter and vander Linde 1995). This is especially true for publicly
traded firms which fear that negative publicity aroundenvironmental neglect could deter stock-market
investors (Mamingi et al. 2008; Dasgupta et al. 2001).
Getting industries on board is accomplished mosteasily when the government and the public push forbetter industrial environmental performance andfinancial markets steer in the same direction. In suchcases, industry has incentives to clean up, especiallyfor financially viable enterprises that are targeting a
global market or first-mover status in an emerging
one (Esty and Winston 2009; Porter and van der
Linde 1995).

Alternative and innovative arrangements are currently
being explored. Such arrangements are likely totake non-legally binding forms which have bothadvantages and limitations compared to international
treaties. For example, in 2016 the Resolution on Air
Quality at the UN Environment Assembly encouraged
intergovernmental action to improve air quality(UNEP 2015). Further, the Resolution on Air Quality
and Health at the World Health Assembly in 2015
recognized air pollution as the world’s greatest
environmental risk and highlighted the key role ofhealth ministries. However, health ministries do nothave the mandate to initiate the necessary changes
to a country’s energy landscape. Later in the same
year, as highlighted throughout the report, air quality
was formally recognized as a development concern
with the inclusion of key indicators on air quality in
SDGs 3, 11 and 13. The SDGs aim to address air
pollution because it is a leading cause of death anddisease worldwide, particularly for people residing incities (WHO 2015).
In a best-case scenario, transnational institutions
and organizations can encourage pro-environmental
agencies within governments to enact policies;
businesses to develop new corporate standards;
and public values to place a greater premium on
clear air. City networks such as Clean Air Asia may beparticularly well positioned in this regard. These
networks have become adept at providing new tools
and transferring knowledge between countries,
in part because they are more flexible thanformal government-to-government agreements.
Transnational networks of scientists – sometimes
termed epistemic communities – also holdpromise to strengthen the interface between
science and policy.

3.5.4 International and regional agreements

3.6 CONCLUSIONS

There is currently no global treaty on air pollution
and one is unlikely to emerge in the near future.
The law on transboundary air pollution representsa patchwork of regional instruments, many ofthem having a soft-law nature. Overall, the legal
landscape on transboundary air pollution can be
described as ad hoc and fragmented with gaps inboth geographical and substantive coverage (forexample, regulated pollutants or pollution sources)(Yamineva and Romppanen 2017).

This chapter reviewed trends in and concrete
examples of the top 25 clean air measures in practice.
Similar to Chapter 2, it divided those measures into
three groups: conventional controls, next-stage
measures and development priority measures. It
demonstrated that achieving significant gains fromreduced exposure to air pollution by 2030 is possible.
By widely implementing the measures – of which
there is already some knowledge and that havealready demonstrated some success – a significant

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133

proportion of the people of Asia and the Pacificcould live longer, healthier lives.
The chapter also draws several important
conclusions for policy makers and otherstakeholders as they contemplate how to
implement those of the measures that fall in linewith their priorities.
The Asia and Pacific region will not be able to growits way out of air pollution problems. Continued
economic growth will be critical to lifting millions
of people out of poverty, but the successful
adoption and effective implementation of pollution
control measures will not result from growthalone. Rather, it is imperative that governments,
businesses and civil society take action. For many
countries, action will need to continue to strengthen
implementation of the conventional controls whilebringing the next-stage measures and development
priority measures into air quality management
programmes. This will require deliberate, solutionoriented, and evidence-based thinking among
decision makers throughout the region.
There is no single set of solutions to air pollution.
Different countries have selected different options
to address similar problems. For instance, China
and Japan are taking very different approaches toreducing emissions of VOCs from solvents. There
are several factors that may influence the options
that countries implement, ranging from the levels
and rates of economic development and thesources and severity of pollution, to the magnitude
and distribution of implementation costs and thedispersion or concentration of industrial structures.
One of the main factors highlighted in this chapter
is the differences in governance arrangements
found throughout the region.
While the selection of solutions may vary, somepatterns do emerge that may be instructive forcountries at different levels of development.
These include a pattern wherein national
environmental agencies often work with otherline agencies to introduce air quality standards
and related legislation as part of initial efforts toimplement conventional controls. From the earlystages of development, it will be important thatenvironmental agencies are able to have access to134

recent science on air pollution causes and impacts.
The timely provision of and easy access tothis knowledge may enable leapfrogging in the
introduction of air quality standards. Yet thenecessary tightening of standards at early stagesof development will be insufficient to achieve therequired level of pollution control. Changing policy
without adjusting allocations of human resources
and supporting infrastructure would be likely to leadto significant implementation gaps in air quality
standards. Commensurate increases in humanresources and technical capacity are essential
when standards tighten.
Many countries in the region have introduced
additional sets of controls after adopting air quality
standards. Frequently, these additional controls
have drawn upon a broad range of instruments
and compliance incentives that motivatedpolluting industries to adopt new technologies
and/or change production processes. Complianceincentives can make the difference between an
effective and ineffective policy.
In several cases, the growing awareness of thecosts of air pollution (and the benefits of controls)
led actors outside environmental agencies tocome up with their own solutions to air pollution
problems. These additional actors include cities
that proposed innovative solutions to local
problems. They also include politicians that use
their position not only to introduce new policies
but also to improve coordination across sectors
and regions. Engaging cities early and involving
them in decision making may help spur innovative
solutions; creating political incentives may
strengthen the political will to support institutionalchanges that can strengthen implementation andbring those innovative solutions to scale.
In moving beyond the conventional controls,enhanced coordination between environmental
and agricultural agencies and across urban andrural areas will be critical. This will be particularly
important in parts of Asia where there is significant
but untapped potential to reduce emissions frommanure and fertilizer. Working with agriculturalagencies, large farms and agro-industry may be
an important first step in realizing those potential

gains. Similarly, cooperation between urban,
peri-urban and rural areas will be needed to solve
what appears to be chiefly urban air pollution.
In expanding the range of measures, stronger
alliances should be sought with industries andinterests promoting clean energy. The growth inrenewables and energy efficiency has already had
significant co-benefits for air quality improvement
as well as climate change. Additional support
from the air pollution community for well-designed
feed-in tariffs, portfolio standards and energy
auditing could enhance the attractiveness of theseinterventions, accelerate their uptake and expand
their coverage.
Regional and international organizations canpromote and help market many of the findingsin this report. The CCAC, with its action-oriented
approach, is well-positioned to advocate greateraction in the Asia and Pacific region in line withthe report’s recommendations. The Asia Pacific
Clean Air Partnership’s (APCAP) emphasis on
regional cooperation and atmospheric science canhelp ensure that decision makers in the region arebasing their actions on the most recent scienceon sources, impacts and solutions. Developmentbanks in the region can consider creating air
pollution facilities that demonstrate provensolutions and leverage additional finance to scale
their implementation.

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135

ANNEXES

ANNEX 1
ANNEX 1.1 DESCRIPTION OF THE
GLOBAL AMBIENT AND HOUSEHOLDAIR POLLUTION (AAP/HAP) MODELSThe integrated exposure-response (IER) approachassumes that:
1. exposure to PM2.5 from diverse combustion		 sources is associated with increased		 mortality from ischemic heart disease (IHD),
		 stroke, chronic obstructive pulmonary		 disease (COPD) and lung cancer (LC), and		 with increased incidence of acute lower
		 respiratory infection (ALRI);
2. the toxicity of PM2.5 differs only with regard		 to inhaled mass (exposure) and not with PM2.5
		 composition;

3. the relation between PM2.5 exposure and		 excess mortality rate ratios (RR) is not		 necessarily restricted to a linear function
		 over the range of human exposure to PM2.5
		 from diverse sources;
4. the relative risk of mortality from chronic		 disease experienced by people exposed to		 ambient air pollution (AAP), second-hand		 tobacco smoke (SHS), household air pollution
		 (HAP), and active tobacco smoking (ATS) is a		 function of long-term cumulative exposure		 quantified in terms of daily average exposure		 concentration and does not depend on the		 temporal pattern of exposure. This assumption		 is required because the temporal nature of		 PM2.5 exposure differs for AAP, SHS, HAP,		 and ATS; and5. the relative risk associated with each type		 of exposure does not depend on the other		 types of exposure.

BOX A1.1.1: METHOD FOR SATELLITE AND CHEMICAL TRANSPORTMODEL-DERIVED ESTIMATES OF AMBIENT AIR POLLUTION USED IN
GLOBAL BURDEN OF DISEASE CALCULATIONS
The approach undertaken by the Institute for Health Metrics and Evaluation (IHME) during the
Global Burden of Disease (GBD) project for ambient air pollution exposure relies on air quality
observations from satellites, combined with information from global chemical transport models
and available ground measurements, to estimate global annual average exposure to PM2.5
systematically, beginning in blocks, or grid cells, covering 0.1×0.1° of longitude and latitude(approximately 11x11 km at the equator).
This combination of data from ground-level monitoring with satellite observations and chemicaltransport models provides a globally consistent estimate of PM2.5 concentrations. A detailed
analysis of country-level trends in exposure was most recently conducted in 2016 using datain five-year intervals from 1990 to 2015. The GBD 2015 estimates for South Asia, for example,
incorporate 44 measurements of PM2.5 (and 419 of PM2.5 estimates derived from PM10) in
India (25 directly measured PM2.5/411 estimated from PM10), Bangladesh (12/1), Bhutan (0/5),
Nepal (0/1), Pakistan (7/0) and Sri Lanka (0/1). Taking into account the population in each grid cellwithin a country, the estimated exposure concentrations were aggregated to national-level
population-weighted averages for a given year.
For ozone (O3), a global chemical transport model was used to calculate a seasonal (summer)
average for each grid cell, while accounting for variation in the timing of the O3 season in different
parts of the world. The process for estimating national-level population-weighted average O3
exposures was the same (Cohen et al. 2017).

138

BOX A1.1.2: METHOD FOR MODEL-DERIVED ESTIMATES OF HOUSEHOLD AIR
POLLUTION USED IN THE GLOBAL BURDEN OF DISEASE CALCULATIONSExposures to HAP have been defined in terms of annual average daily exposure to household
concentrations of PM2.5 resulting from the use of solid fuels, including agricultural residues,charcoal, coal, dung and wood. Data on fuel use are derived from a number of national andsub-national surveys, including demographic and health surveys, living standards measurement
surveys, multiple indicator cluster surveys and country-specific sources, and from the WHO fuel-use
database (GBD 2017b; World Bank 2016).
Since direct measures of HAP are reported only in a limited number of research studies (Balakrishnan
et al. 2011; Northcross et al. 2015; Williams et al. 2015) estimation of exposure to HAP (for purposesof disease burden estimation) has been performed using spatiotemporal Gaussian process
regression (GPR) modelling. Solid fuel estimates are first translated into indoor PM2.5 concentrations
and then into exposures separately for men, women and children. The first step – from fuel use
estimates to room concentration estimates – relies on indoor PM2.5 data from 90 studies in 16
countries. For GBD 2016, measured PM2.5 concentrations were related to IHME’s sociodemographic
index and used to predict exposures for all locations and years (GBD 2017b; World Bank 2016).
Indoor concentrations are translated to exposures by applying the ratio of personal exposures toarea concentrations based on a sub-set of seven studies from six countries (GBD 2017b; WorldBank 2016). The exact input measurements used for these estimates are unknown; as such, future
work should validate estimated exposures with actual, repeated, on-the-ground measurements of
exposure using personal aerosol samplers. Such work is underway as part of the PURE project(Arku et al. 2018).

While the assumptions do raise uncertainties
regarding the burden estimates, without direct
epidemiological evidence and without empiricalevidence against which to evaluate thoseassumptions, the IERs have provided a consistentbasis for estimating burdens attributable to AAP
and HAP across world regions.

ANNEX 1.2 EXPERIMENTAL AND
MODELLING STUDIES ON OZONE CROP
IMPACTS
Studies carried out in open-top chambers (OTCs)
under ambient ozone (O3) concentrations revealed
reductions in the yield of crops compared to thosewhere ambient O3 was filtered. Yield reductions inthree wheat cultivars ranged between 8.6% and20.7% (Rai et al. 2007; Rai et al. 2010) in India atmean ambient concentrations of 44 parts per billion(ppb), and in three cultivars between 37% and 46% inPakistan at mean ambient O3 concentrations of 60
ppb using OTCs (Wahid 2006). Similarly, reductions of
10.2–15.9% in four rice cultivars, 4.0–5.5% in
two maize cultivars, 7.0–35.9% in four mustard
cultivars and 12–20% in two soybean cultivars
were reported at ambient O 3 concentrations,taking O3 exposure of 50 ppb as the reference(Rai et al. 2016).
Yield reductions increased when crop plants were
exposed to elevated levels of O3 simulated in various
experiments. Different cultivars of wheat showed
yield reductions of 12.8–39.0% at ambient +10 ppb
and 38–46% at ambient +20 ppb O3 introduced for
four hours daily from germination to maturity (Sarkar
and Agrawal, 2010). Elevated O3 levels in OTCs
significantly reduced winter wheat yield comparedwith charcoal-filtered air (CF) control, i.e. by 8.5–58%
for O 3 treatment one (AOT40 of 14.3–22.6
ppm.h) and 40–73% for O3 treatment two (AOT40

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139

of 24.2–61.9 ppm.h) treatments at the Jiaxing
site, China (Wang et al. 2012). Similarly, Zhu et al.
(2011) conducted a three consecutive seasonal
free air concentration enrichment (FACE) study
and reported that a mean 25% enhancement above
ambient O3 (45.7 ppb) reduced the wheat grain
yield by 20% with a variation range of 10–35%
among cultivars and seasons. The reduction ofindividual grain mass accounted mostly for theyield loss by O3 that showed significant difference
between the cultivars (Zhu et al. 2011). Akhtar etal. (2010) reported reductions varying between
11.6–47.6% at 60 ppb and 44.5–65.6% at 100 ppb
O3 exposure of two Bangladeshi wheat cultivars.
Rice cultivars showed yield reductions ranging
from 27–31% at ambient +10 and from 30–45%
at ambient +20 ppb O3 (Sarkar and Agrawal 2012).
As compared with the sub-ambient O3 control,
the mean yield losses in rice were 10–34% and
16–43%, respectively, when plants were exposed
to O3 treatment one (AOT40 of 13.8–29.5 ppm.h)and O3 treatment two (AOT40 of 32.1–82.6 ppm.h)treatments, respectively, at the Jiaxing site, China(Wang et al. 2012). Similarly, elevated O3 in the
FACE experiments significantly reduced the grain
yield by 12% when averaged across all the tested
cultivars – hybrid rice cultivars SY63 and LYPJ, andinbred cultivars WJ15 and YD6 (Shi et al. 2009). An
OTC study for two Malaysian local rice cultivars
found that under the 8-h mean exposure of ozoneof 32.5 ppb, the yield of one cultivar was reduced
by 6.3% while the effect on the other cultivar was
not statistically significant (Ishii et al. 2004). An OTC
study conducted in peri-urban Hanoi, Viet Nam, foundthe grain yield loss of a locally grown Vietnameserice cultivar to be 4.5% for every 10 ppb increase inO3 from the ambient level of 6 ppb to the highest
exposure level of 113 ppb, seven hours a day, 35 days
covering the second half of the vegetative and early
reproductive stages (Van et al. 2009).
Maize cultivars were found to be relatively resistantto elevated O3 as yield loss varied from 7.2–9.5%
and 10.1–13.8% respectively at ambient +15
and ambient +30 ppb O3 concentrations (Singhet al. 2014). Among leguminous plants, mungbean showed reductions varying from 9.8–15.4%
and soybean from 12–20% at ambient + 10 ppb
elevated O 3 concentrations (Chaudhary andAgrawal, 2015; Singh et al. 2010). Oil-yielding crop

140

mustard showed yield reductions of 12.5–48.5%
among three cultivars (Singh et al. 2012) and one
cultivar of sunflower showed 45.7% reduction atambient +10 ppb O3 concentration (Tripathi andAgrawal 2012). OTC experiments conducted for a
local peanut cultivar in Viet Nam found significant
reductions in plant height, leaf area and dry weightat harvest time due to exposure to elevated O3. On
average, the seed yield reduced by about 4.6% for
every 10 ppb increase in O3 from the ambient levelof 6 ppb to a highest exposure level of 113 ppb,
seven hours a day during 30 days of the flowering
stage (Van and Kim Oanh 2009). The individual
grain size was significantly decreased in wheat
and rice exposed to elevated O3 (Zhu et al. 2011;
Shi et al. 2009). A summary of the results fromexperimental studies is given in Table A1.4.1.
Modelling methods for quantifying the impacts ofozone on crops
Two particular modelling methods are discussed
below that can incorporate the direct and indirect
impacts of O3 on plant growth and ecosystemprocesses which are useful to assess yield loss infuture climate conditions.
1) Semi-empirical O3-effect modelling methods		 have been developed more recently; these		 use the same statistical relationships but are		 built in to process-based ecosystem modelling		 frameworks. It allows these models to assess		 the direct and indirect impacts of O3 on plant		 growth and ecosystem processes such as		 photosynthesis, carbon (C) allocation and		 transpiration (Tai et al. 2014; Ren et al. 2007;
		 Felzer et al. 2004; Ollinger et al. 1997; Reich		 1987). Most land-ecosystem models are		 process based to simulate the dynamics in		 ecosystem function and structure as		 influenced by global environmental changes,
		 from cell, leaf, community and ecosystem to		 regional and global levels, and from daily,
		 monthly and seasonal to yearly and longer
		 scales. Some of those models have incorporated
		O3 effects, as one of multiple environmental
		 drivers, on ecosystem C and water dynamics,
		 using the statistical relationships described		 above, the most popular index being AOT40,
		 used by Felzer et al. (2004), Ollinger et al.(1997)
		 and Ren et al. (2007).

2) Dynamic process-based models that consider
		 effective O3 flux (the stomatal O3 flux which		 exceeds the detoxification capacity of the		 plant) and effects on photosynthesis
		 (Massman 2004; Martin et al. 2000); these		 approaches have been scaled to estimate
		 consequent effects on C assimilation in		 forest canopies (Deckmyn et al. 2008; Martin
		et al. 2001) and for ecosystem plant functional
		 types in the MOSES-TRIFFID land surface

		
		
		
		
		
		
		
		
		

model (Sitch et al. 2007). However, few
process-based O3 models have been applied
at a large scale due to limited O3 flux dataand complicated model parameterization andlittle attention has currently been devoted
to developing such models for crops. An
obvious way to achieve this is to develop a
more comprehensive mechanistic approach
to modelling O3 impacts on crops.

TABLE A1.1.1 EFFECTS OF OZONE ON MAJOR CROPS AND FOREST TREES IN ASIA
FROM THE EXPERIMENTAL STUDIES (% YIELD REDUCTION)
Species

India/South Asia

China/East Asia

Wheat

• OTC, 44 ppb (8h), 8.6–21%• FACE, +45.7 ppb (8h),(Rai et al. 2007)• OTC, 60 ppb (8h), 37–46%(Wahid 2006)• OTC, +10 & +20 ppb (4h),Southeast Asia

20% (Zhu et al. 2011)• OTC, 70–100 ppb,

8.5–58%; 150-200 ppb,
40–73% (Wang et al. 2012)12.8 – 46% (Sarkar andAgrawal 2010)• OTC, 60–100 ppb (8h),11.6–65.6% (Akhtar
et al. 2010)
Rice• OTC, 35 ppb (8h), 34-38%• OTC, +50–+100 ppb (8h),(Wahid et al. 1995)• OTC, +10 & +20 ppb (12h),
27–45% (Sarkar andAgrawal 2012)

8.2–26.1% (Fenget al. 2003)• FACE, +56–+59 ppb (8h),
15–17.5% (Shi et al. 2009)• OTC, 70–100 ppb,
10–34%; 150–200 ppb,
16-43% (Wang et al. 2012)• OTC, 60–100 ppb (8h),3–34% (Inada et al. 2008;
Yamaguchi et al. 2008)

Maize

OTC, +15 & +30 ppb (8h),7.2–13.8% (Singh et al. 2014)

Soya bean• OTC, +10 ppb (4h),• OTC, 32–113 ppb (7h),10–48% (Van et al. 2009)• OTC, 32.5 ppb (8h), 6.3%
(Ishii et al. 2004)• CC, 150 ppb (8h), 12.3%(Ariyaphanphitak
et al. 2005)

12–20% (Singh et al. 2010)• EDU (400 ppm), 40–75

ppb (6h), 35–68% (Wahid
et al. 2001)

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS141

TABLE A1.4.1 EFFECTS OF OZONE ON MAJOR CROPS AND FOREST TREES IN ASIA
FROM THE EXPERIMENTAL STUDIES (% YIELD REDUCTION) (contd.)
Species

India/South Asia

China/East Asia

PeanutMungbean

OTC, 32-113 ppb (7h),27–49% (Van and Kim
Oanh, 2009)• OTC, +10 ppb (6h),9.8–15.4% (Chaudharyand Agrawal, 2015)• EDU (500 ppm), 33 ppb(8h), 70% (Agrawal
et al. 2005)• 8–15 ppm.h AOT for 6

Forest trees

months, 10% reductionof whole plant dry mass
(Kohno et al. 2005)• OTC, 38.2 ppm.h (AOT40),
13–26% total biomass(Zhang et al. 2012)
Other crops

142

Southeast Asia

OTC, +10 ppb (8h), 45.7 ppb
for sun flower (Tripathi andAgrawal 2012)

ANNEX 2.1 THE MODELLING TOOLSIn order to identify promising policy intervention
options that could deliver effective improvements
in air quality in Asia together with progress
towards the Sustainable Development Goals,
this report employs a suite of well-establishedscientific tools that deliver a holistic perspectivethat integrates geo-physical, economic, social
and institutional dimensions across different
spatial and temporal scales.
2.1.1 The Greenhouse gas – Air pollution
Interactions and Synergies (GAINS) model
2.1.1.1 Overall approach
The GAINS model is a widely-applied policy analysis
tool to identify cost-effective policy interventions

to reduce the health impacts of air pollution while
maximizing co-benefits with other policy priorities(Reis et al. 2012; Amann et al. 2011; Hordijk andAmann 2007).
As a scientific tool for integrated policy assessment,
the GAINS model describes the air pollution
pathways from atmospheric driving forces toenvironmental impacts. It brings together information
on economic, energy and agricultural development,
emission control measures and costs, atmosphericdispersion and source sensitivities. GAINS quantifies
the emissions and impacts of nine air pollutants– sulphur dioxide (SO2,) nitrogen oxides (NOx),particulate matter with aerodynamic diameters equal
to or less than 2.5 and 10 micrometres (µm) (PM2.5
and PM10), black carbon (BC,) organic carbon (OC),carbon monoxide (CO), ammonia (NH3) and volatileorganic compounds (VOCs) – and six greenhousegases – carbon dioxide (CO2), methane (CH4),
nitrous oxide (N2O), hydrofluorocarbons (HFCs),

GAINS

IEA WEO + FAO

Future economic activities

Energy and agricultural scenarios

Emission control measures

GISS and GEOS-Chem
Emissions of air pollutants
and greenhouse gases

Climate impacts
Ozone concentrations

DO3E
Ambient air quality PM

Crop impacts

Sustainable Development Goals

ANNEX 2

WHO GBD
Population exposure toambient PM and indoor pollution

Health impacts

FIGURE A2.1: THE MODEL SUITE USED FOR THIS ANALYSIS AND
THE INTERACTIONS BETWEEN MODELSAIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

143

perfluorocarbons (PFCs), sulphur hexafluoride(SF6) – on human health, crops, acid deposition andlong-term radiative forcing in a multi-pollutant/multi-effect perspective.
GAINS explores the co-control of more than 1,500
specific measures on multiple air pollutant andgreenhouse gas emissions, identifies trade-offs andwin-win measures, and assesses their impacts onambient air quality, population exposure, resulting
health and vegetation impacts, and various
climate metrics.
GAINS is currently implemented for 196 countries/
world regions with a global coverage, including
more than 100 regions in Asia. The GAINS
model and databases are accessible at http://
gains.iiasa.ac.at.
The methodology follows the Global Burden of
Disease (GBD) 2010/2013 studies and includes
the effects of indoor pollution from household
solid fuel use.

2.1.1.2 A multi-pollutant/multi-effect perspective
GAINS can follow pollutants from their sources totheir impacts, and thereby simulates the impacts ofspecific policy interventions on multiple outcomes.
In its optimization mode, GAINS identifies theleast-cost balance of emission control measuresacross pollutants, economic sectors and countries
that meet user-specified air quality and climate
targets (Figure A2.2).
GAINS addresses air pollution impacts on humanhealth from PM2.5 and ground-level ozone (O3),vegetation damage caused by ground-level O3, theacidification of terrestrial and aquatic ecosystems
and excess nitrogen (N) deposition of soils, inaddition to the mitigation of greenhouse gas
emissions. It captures the interactions between
these multiple effects and the associatedpollutants – SO2, NOx, particulate matter (PM),non-methane volatile organic compounds(NMVOCs), NH 3, CO 2, CH 4, N 2O, fluorinatedgases (F-gases) – as well as the simultaneous
co-control of multiple pollutants of specificemission reduction options (Figure A2.3).

Energy/agriculture
projections

Emissions control option

Emissions

Costs

OPTIMIZATION

Atmospheric dispersion

Air pollution impacts,basket of greenhouse gas
emissions

Environmental targets

FIGURE A2.2: THE FLOW OF INFORMATION IN THE COST-EFFECTIVENESSANALYSIS OF THE GAINS MODEL

144

2.1.2 Emission estimates

xi,k,m,p

For each of the pollutants listed in Figure A2.3, GAINS
estimates current and future emissions based on
activity data, uncontrolled emission factors, theremoval efficiency of emission control measuresand the extent to which such measures are applied:

where:i, k, m, p
Ei,p

Ai,k

efi,k,m,pcountry, activity type, abatement
measure, pollutant, respectively;
emissions of pollutant p (for SO2, NOx,
VOCs, NH3, PM2.5, PM10, BC, OC, CO2,
CH4, N2O, F-gases) in country I;
activity level of type k (e.g., coalconsumption in power plants) incountry i:emission factor of pollutant p for
activity k in country i after applicationof control measure m;

PM
(BC,
OC)

SO2

NOx

share of total activity of type k
in country i to which a control measurem for pollutant p is applied.

This approach allows capturing critical differences
across economic sectors and countries that
could justify differentiated emission reduction
requirements in a cost-effective strategy. Structuraldifferences in emission sources are reflected
through country-specific activity levels. Major
differences in emission characteristics of specificsources and fuels are represented throughsource-specific emission factors, which accountfor the degrees at which emission control
measures are applied. GAINS estimates future
emissions according to the equation aboveby varying the activity levels along exogenous
projections of anthropogenic driving forces andby adjusting the implementation rates of emission
control measures.

VOC

NH3

CO

CO2

CH4

N2O

HFCs
PFCs
SF6

Health impacts:
PM (Loss in life expectancy)
O3 (Premature mortality)
Vegetation damage:O3 (AOT40/fluxes)
Acidification(Excess of critical loads)
Eutrophication(Excess of critical loads)
Climate impacts:
Long-term (GWP100)
Near-term forcing
Carbon deposition to the
Arctic and glaciersNote:– important impact;– small impact. GWP – global warming potential.
AOT40 – the sum of the differences between hourly O3 concentration and 40 parts per billion (ppb) for each hour when theconcentration exceeds 40 ppb during a relevant growing season.

FIGURE A2.3: THE MULTI-POLLUTANT/MULTI-EFFECT FRAMEWORK OF THE GAINS MODEL

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

145

2.1.3 Air pollution control costs
Basically, three groups of measures to reduce
emissions can be distinguished:• Behavioural changes reduce anthropogenic
		 driving forces that generate pollution. Such		 changes in human activities can be autonomous
		 (for example, changes in life styles), they could		 be fostered by command-and-control
		approaches (for example, legal traffic restrictions),
		 or they can be triggered by economic incentives
		 (for example, pollution taxes, emission trading		 systems, etc.). The GAINS concept does not		 internalize such behavioural responses, but		 reflects such changes through alternative		 exogenous scenarios of the driving forces.
• Structural measures that supply the same		 level of (energy) services to the consumer
		 but with less polluting activities. This group		 includes fuel substitution (for example,		 switching from coal to natural gas) and		 energy conservation/energy efficiency
		 improvements. The GAIN model introduces		 such structural changes as explicit emission
		 control options.
• A wide range of technical measures has been		 developed to capture emissions at their		 sources before they enter the atmosphere.
		 Emission reductions achieved through these		 options neither modify the driving forces		 of emissions nor change the structural
		 composition of energy systems or agricultural
		 activities. GAINS considers about 1,500
		 pollutant-specific end-of-pipe measures for		 reducing SO 2, NO x, VOCs, NH 3 and PM
		 emissions and several hundred options for		 greenhouse gases and assesses their		 application potentials and costs.
The GAINS model estimates the various costs ofthe dedicated emission control measures. Theseestimates are based on international experiencein technology costs and consider country-specificcircumstances that justify differences in costs acrosscountries for objective reasons. GAINS does not,however, quantify the full costs of system changes(for example, of a decarbonization strategy) that146

imply important (macro-economic) feedbacks andpotential changes in international competitiveness.
Also, the GAINS model does not quantify costs of
behavioural changes, as it does not assess welfare
costs and consumer utilities.
Assuming a free market for emission control
technologies, the same technology will be available
to all countries at the same costs. However,country- and sector-specific circumstances (suchas size distributions of plants, plant utilization, fuelquality, energy and labour costs, etc.) lead tojustifiable differences in the actual costs at whicha given technology removes pollution at different
sources. For each of the 1,500 emission control
options, GAINS estimates their costs of local
application considering annualized investments (Ian),
fixed (OMfix) and variable (OMvar) operating costs,
and how they depend on technology m, country iand activity type k. Unit costs of abatement (ca),related to one unit of activity (A), add up to:Thus, cost figures estimated with GAINS refer tothe costs of implementing dedicated emission
control measures. They do not include benefits
from lower emissions that lead to cleaner air, suchas improved health conditions, crop productivity
and undisturbed ecosystems.
GAINS estimates costs of societal resources
diverted for the purposes of emission reductions.
These estimates do not include transfer payments(for example, taxes, profits, subsidies), as these
do not represent net costs to the society. Up-front
investments are annualized over the technicallifetime of the equipment, using a discount rate of
4% that is appropriate for social planning purposes.
Obviously, private actors that need to consider
profits, taxes and other cost components will apply
different discount rates.
2.1.4 Modelling methane emissions
The estimation of anthropogenic CH4 emissions
in the GAINS model follows the same generalbottom-up emission inventory approach as used forother pollutants in GAINS; activity levels multipliedby emission factors that have been adjusted
for impacts on emissions from adopted control
technology. A future emissions possibility range isidentified between a baseline emission scenariothat describes future emissions without further
uptake of emission control technology thanprescribed in current legislation, and a maximum
technically feasible reduction (MFR) scenario that
describes the lowest possible emissions giventhat existing control technology is implemented
to a maximum feasible extent. The emission
reduction pathway between the baseline andMFR scenarios is described by a marginal
abatement cost curve. The GAINS model covers
all anthropogenic sources of CH4 emissions, thatis emissions from livestock enteric fermentation andmanure management, anaerobic decompositionof organic waste and wastewater, incomplete
combustion, and fugitive emissions from fossil
fuel extraction, processing, transmission anddistribution (Höglund-Isaksson 2012).
Livestock CH4 emissions are estimated from theFood and Agriculture Organization of the United
Nations (FAO) activity levels and country-specificemission factors that take account of different
types of manure management systems, milk
productivity levels and indoor housing times.
Identified abatement potentials include breeding
schemes targeted at improving both productivity
and animal fertility and longevity, options to change
animal feed composition and anaerobic digestionof manure for biogas recovery.
The GAINS model includes an extensive structure
for estimating emissions from flows of different
types of solid waste – food, paper, textile, wood,
plastics/rubber, etc. – from both industrial andmunicipal sources. Activity data on generationof different types of waste in historical years istaken from international statistics databases
and projected into the future by taking account of
impacts from changes in per person income levels
and urbanization rates. The future abatement
potential is determined by identifying possible
improvements to the current destination of solid
waste flows, that is, to what extent solid waste iscentrally collected or not, and if collected, to what
extent it is recycled, incinerated with or without

energy recovery, or disposed of at managed or
unmanaged landfills, and if uncollected, to what
extent it is openly burned or simply scattered.
Fugitive CH4 emissions from coal mining, oil andgas extraction, and natural gas transmission anddistribution are estimated making extensive use ofcountry/region- specific information on, for example,
calorific values of coal, oil and gas, surface orunderground coal mining, generation and recovery
rates of associated petroleum gas, volumes ofassociated gas flared as estimated from satellite
images, offshore or onshore production, extent of
unconventional gas production and length of onshore
gas transmission pipelines. Abatement potentials incoal mining are assessed separately for emissions
released during degasification activities before
mining begins, during mining through ventilation
shafts or during post-mining activities. For oil andgas extraction, abatement potentials are assessed
separately for the handling of associated gas and forunintended leakages from equipment and processes.
Finally, leakage from consumer gas distribution
networks is accounted separately for domestic
and industrial/power plant users to reflect different
average leakage rates (Höglund-Isaksson 2012).
2.1.5 Modelling hydrofluorocarbon emissions
A baseline projection of future HFC emissions in
Asia has been developed following the methodology
described by Purohit and Höglund-Isaksson (2017).
For major sources – residential and commercial
air conditioning, mobile air conditioning anddomestic refrigeration – the consumption of HFC
in historical years 2005 and 2010 has been derived
in a consistent manner across countries, startingfrom a compilation of data on underlying drivers,
such as number of vehicles by vehicle types,
commercial floor space area, cooling degree days,
per person income, average household sizes, current
equipment penetration rates, etc. Hydrofluorocarbon
consumption in commercial and industrial
refrigeration, refrigerated transport, foams andother smaller HFC sources, varies greatly between
countries, due for example to differences in industrial
structures and consumption patterns, which makes
it more challenging to model the HFC consumption
consistently across countries from underlying
data. For these sectors, information on HFC

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147

consumption has been compiled from various
published sources (GIZ 2014; UNDP 2014a, b;
UNEP 2011; MoEF 2009), or has been derived in aconsistent manner from underlying activity datausing default factors from literature.
Drivers for future HFC consumption are consistent
with the macroeconomic development projectedin the 2016 World Energy Outlook (WEO) of theInternational Energy Agency (IEA) (IEA 2016).
Effects on HFC emissions from uptake of alternativetechnologies and/or substances are only accounted
for to the extent that these technologies have alreadybeen adopted or will be required to be adopted in the
future to comply with implemented legislation, forexample, Japan’s Act on the rational use and proper
management of fluorocarbons. The baseline does notaccount for future uptake of abatement technology
on the sole basis of estimated marginal abatement
costs turning out zero or negative. Apart fromuncertainty being high in cost estimates in general,
there may exist other barriers for technology spread
and adoption, such as institutional or informational
barriers, which are difficult to reflect in a generalmodel setting like GAINS.

The response of ambient PM2.5 concentrations
to emission changes of PPM, SO2, NOx, NH3, and
VOCs in each region (section 2.1.2) is computedwith transfer coefficients, which have been derived
from sensitivity simulations with a full EMEP
atmospheric chemistry transport model on a
0.5×0.5° grid (Simpson et al. 2012). In eachsensitivity simulation, emissions of one pollutant(PPM, SO2, NOx, NH3, VOCs) from one source
region are reduced by 15%. For PPM, additional
sensitivity simulations were undertaken which
reduce only low-level sources. Linearizing the
response of grid concentrations to these emission
changes yields the transfer coefficient, i.e. theimpact of one unit of emissions of pollutant
emitted from region on ambient concentrations
in grid cell :Total PM2.5 concentrations in each grid cell arethen calculated as the sum of transfer coefficients
multiplied with the scenario emissions:

2.1.6 Modelling ambient levels of PM2.5
Ambient air quality in each scenario is estimatedwith the GAINS model. The annual ambient PM2.5
concentration in GAINS includes two components:
1) a regional background concentration related		 to emissions from remote and high-stack		 sources, calculated with linear source		 receptor transfer coefficients from sensitivity
		 simulations of the European Monitoring and		 Evaluation Programme (EMEP) chemical		 transport model (Simpson et al. 2012) at a		 resolution of 0.5×0.5°;2) a sub-grid increment related to primary PM2.5
		 (PPM) emissions from local low-level sources,		 including domestic and transport emissions
		 as well as open burning of waste. The
		 combined results are used to estimate		 population exposure to ambient PM 2.5
		concentrations.

148

where is a grid-specific residual from boundary
conditions and nonlinearities, which is a small
positive value for most grid cells.
For cities of more than 100,000 inhabitants,
concentrations are calculated individually below
the grid resolution. GAINS employs the assumptionthat fine-scale variations in ambient PM
concentrations are mainly related to emissionsof primary PM from low-level sources such as
residential combustion, road traffic, and open
burning of waste (Kiesewetter et al. 2015). Therefore,
modelled concentrations are re-distributed withineach grid cell, reflecting the spatial pattern of
low-level emission sources which is derived
by combining fine resolved population data at
approximately 100x100 metres (m) resolution
obtained from worldpop.org.uk (Gaughan et al. 2013),
with information on urban and rural preferencesof household fuel use. The local transfer coefficient
applied to low-level emissions is derived from alinear regression on the additional perturbation
run changing only the low-level emissions.

with a particularly large and rather reliable data setof PM2.5 ground-level measurements.

Validation of model results for ambient PM2.5

Comparison with results from other models

Figures A2.4 and A2.5 show scatter plots ofmodelled annual mean PM2.5 concentrations forindividual cities in 2015, compared to observations.
The availability of monitoring data differs strongly
between individual countries – while in China alarge data set is publicly available through thestatistical yearbooks, the data coverage in manyother countries is rather low and the quality ofmonitoring data is uncertain. In many cases theWorld Health Organization (WHO) Ambient Air
Quality database is the only publicly available
source of information. However, reported PM2.5
values are often not directly measured but derived
from PM10, as direct PM2.5 measurements are
not always available. The degree of agreement
between model and observations varies between
individual countries – notably, there is good
agreement and high correlation in China, a country

While comparing model results against monitoringdata is essential for establishing credibility, thecurrent paucity of monitoring data for PM 2.5
in many Asian countries does not allow a full
spatial coverage of such comparison. Thus, it
is instructive to compare concentration fields
obtained with different atmospheric chemistrymodels. To this end, only a limited comparisonhas been carried out, restricted to results of
GAINS and the NAQPMS model of the Institute ofAtmospheric Physics of the Chinese Academy of
Sciences (CAS) in Beijing. Both models have been
run for the meteorology of 2015, with independent
emission estimates for 2015. In general, there isa good match of computed PM2.5 concentrations,although GAINS estimates higher values in the westof Asia, due to larger emissions of natural sources(soil dust) (Figures A2.6 and A2.7).

India

PM 2.5 modelled (μg/m3)

PM 2.5 modelled (μg/m3)

China

PM 2.5 observed (μg/m3)
China Statistical Yearbook 2014
China Statistical Yearbook 2015
China Statistical Yearbook 2016
WHO AAP database May 2016

PM 2.5 observed (μg/m3)
Bisht et al. 2015
Delhi Pollution Control Committee
Pallavi Pant et al. 2015
Sagnik Dey et al. 2012
Sarath et al. 2013
WHO AAP database May 2016

Note: Different observational data sets are indicated by different symbols. Observations referring to the same city
are connected by lines to indicate the inter-annual and spatial variability within a city.

FIGURE A2.4: COMPARISON OF GAINS MODEL RESULTS WITH NATIONAL MONITORINGDATA AND SATELLITE-BASED DATASETS (DEY et al. 2012, FOR INDIA),AS WELL AS DATA REPORTED IN THE WHO DATABASE (2016)

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

149

JapanPM 2.5 modelled (μg/m3)

Iran

PM 2.5 modelled (μg/m3)

PM 2.5 modelled (μg/m3)

Bangladesh

Repiblic of Korea

Malaysia

Mongolia

PM 2.5 modelled (μg/m3)

PM 2.5 observed (μg/m3)

PM 2.5 modelled (μg/m3)

PM 2.5 observed (μg/m3)

PM 2.5 modelled (μg/m3)

PM 2.5 observed (μg/m3)

PM 2.5 observed (μg/m3)

Myanmar

Nepal

Pakistan

PM 2.5 modelled (μg/m3)

PM 2.5 modelled (μg/m3)

PM 2.5 observed (μg/m3)

PM 2.5 modelled (μg/m3)

PM 2.5 observed (μg/m3)

Sri Lanka

Taiwan, Province of China

ThailandPM 2.5 observed (μg/m3)

PM 2.5 modelled (μg/m3)

PM 2.5 observed (μg/m3)

PM 2.5 modelled (μg/m3)

PM 2.5 observed (μg/m3)

PM 2.5 modelled (μg/m3)

PM 2.5 observed (μg/m3)

PM 2.5 observed (μg/m3)

PM 2.5 observed (μg/m3)

FIGURE A2.5: COMPARISON OF GAINS MODEL RESULTS WITHDATA REPORTED IN THE WHO DATABASE (2016)

150

105

65

50
WHO Interim Target 1

PM2.5 (μg/m3)

80

35
25

WHO Guideline

15
10

FIGURE A2.6: AMBIENT LEVELS OF PM2.5 IN ASIA IN 2015
AS MODELLED BY GAINS

80°E

20

90°E

40

100°E

110°E

120°E

130°E

60

80 100120140

FIGURE A2.7: LEVELS OF PM2.5 IN AMBIENT AIR IN 2015 (μg/m3)
Source: CAS, Beijing, China

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2.1.7 Population exposure to PM2.5
As a metric for population exposure to PM2.5 inambient air, GAINS computes the annual average
population-weighted mean concentrations ofambient PM2.5. For this purpose, calculated PM2.5
concentrations at the spatial resolution of urban
and rural parts of each 0.5° grid cell are multipliedwith population numbers specified at the same
resolution for the same scenario year, summed
across the region and then divided by the total
population for the respective region. Fine-scale
gridded population is based on open-source
data sets at approximately 100×100m resolution
developed by worldpop.org.uk (Gaughan et al. 2013).
Total country population numbers are calibrated to
UN world population statistics for 2010 and subject
to national population trends from the UN World
Population Prospects 2010 (UNDESA 2011), taking
into account future urbanization trends as estimatedin the UN World Urbanization Projections 2011
(UNDESA 2012).
2.1.8 Health impacts from ambient PM2.5
GAINS computes the impact on the projected future
population of exposure to ambient PM2.5 after first
calculating the impact of primary PM, SO2, NOx, NH3,
and VOC emissions in each of the 100 regions in
Asia on ambient PM2.5 concentrations, as describedin section 2.1.6. To capture the level of concentrationof PM2.5 in cities, grid concentrations are calculated
separately for the urban and rural parts of each gridcell. The resulting PM2.5 levels are used to estimate
population exposure.
The health impact assessment follows themethodology developed in the context of the GBD
2013 assessment (Forouzanfar et al. 2015) andapplied by WHO (2016) in their Burden of Ambient
Air Pollution assessment. Relative risk of mortality
is calculated for all relevant diseases (ischemic heartdisease, chronic obstructive pulmonary disease,stroke, lung cancer and acute lower respiratory
infections) from the integrated exposure-response(IER) relationships used in the above-mentioned
studies. Country-specific baseline mortality rates
for five-year-interval age groups are derived fromUN data (UNDESA 2011) for all scenario years.

152

The country- and age-specific relative contributionsof individual diseases to total baseline deaths
are taken from the GBD 2013 assessment(Forouzanfar et al. 2015) and, in the absenceof better information, are assumed to remain
constant in the future. The approach inherently
takes into account the effect of the ageing
population, which increases the number of people
vulnerable to air-pollution-related diseases overtime. For historic years, the resulting central
estimates are well within the uncertainty rangesof other studies such as GBD 2013 (WHO 2016).
The calculation of total air pollution-related deaths
assumes that ambient and indoor pollution are
independent risks.
The uncertainties of health impact calculations arequantified employing a full Monte Carlo approachfor the key parameters of the disease-specific
IER functions including the counterfactual
concentrations.
2.1.9 Health impacts from exposure to indoor
pollution
The exposure of indoor air pollution is calculated
for residents using solid fuel for cooking. A typical
exposure of 300 micrograms per cublic metre(μg/m3) is assumed for traditional stoves and70 μg/m3 for clean stoves, based on the wide
range of observed concentrations (Balakrishnan
et al. 2013). Corresponding relative risks arederived from the GBD 2013 IER functions which
are used in this assessment (Forouzanfar et al.
2015). The numbers of solid fuel users using
traditional and clean cookstoves have been
estimated by the IEA, coherent with the different
energy scenarios (IEA 2016).
The human health impact in terms of the premature
mortalities of each scenario is estimated for all
relevant diseases, including ischemic heart disease,stroke, chronic obstructive pulmonary disease,lung cancer and acute lower respiratory infections
in five-year steps, equivalent to the calculations forambient air pollution.

ANNEX 2.2 THE GISSCOMPOSITIONCLIMATE AND GEOS-CHEM
CHEMICAL TRANSPORT MODELS
2.2.1 Modelling ground-level ozone
Estimates of concentration levels of ground-level O3
resulting from the emission scenarios produced by
GAINS have been estimated with:i) the Goddard Institute for Space Studies
		 GISS) Global Climate Model; andii) the GEOS-Chem atmospheric chemistry		 transport model.
Ozone concentrations were simulated globally at
2x2.5° resolution in these models. Identical gridded
anthropogenic emissions for the current legislationand climate policy scenarios at 0.5x0.5° resolution
were used as input into both models.
ModelE2 simulates both the general circulationand chemistry of the atmosphere, with theinternally generated meteorology fully interactingwith the gaseous and aerosol chemistry. These
interactions are fully discussed in Schmidt et al.
(2014). A thorough evaluation of the O3 chemistry
and the processes contained within ModelE2
can be found in Shindell et al. (2013). In short, forprocesses applicable to this analysis, troposphericNOx-(HOx)-Ox-CO-CH4 chemistry, which also includes
peroxyacyl nitrates (PAN), isoprene, alkyl nitrates,
aldehydes, alkenes, and paraffins are simulated.
ModelE2 features online calculations of NOx fromlightning, online calculations of biogenic isoprene andterpenes, online calculations of natural dust (Miller
et al. 2006), online calculations of sea-salt emissions(Koch et al. 2006), prescribed biogenic alkene andparaffin emissions, NOx emissions from soil, andprescribed volcanic emissions (Miller et al. 2014).
All GEOS-Chem simulations were run using 2015
GEOS-FP assimilated meteorology, provided by the
Global Modeling and Assimilation Office (GMAO)
at the NASA Goddard Space Flight Center, andthe secondary organic aerosol (SOA) chemicalmechanism (Pye et al. 2010; Pye and Seinfeld2010), which simulates the coupled oxidant-aerosol
chemistry of the troposphere. In contrast to theModelE2 simulations, due to the consistent driving

meteorology in all simulations, the impacts ofa changing climate were not captured and thedifferences between the time-sliced simulations arestrictly due to emission changes. All simulations
featured a 1-year spin-up period, followed by thefull-year simulations that were used in the analysis.
With the exception of volcanic SO2 and biomassburning emissions, which were retrieved from the
AEROCOM dataset and the Global Fire Emissions
Database (GFED4) (Giglio et al. 2013), respectively,
all non-anthropogenic emissions respond tometeorology within the model. This includes
lightning NO x (Murray et al. 2012), soil NO x
(Hudman et al. 2012), biogenic emissions (MEGAN;
Guenther et al. 2006), and dust emissions generated
from the dust entrainment and deposition (DEAD)
scheme (Zender et al. 2003). All emissions were
processed through the Harvard NASA Emission
Component (HEMCO; Keller et al. 2014). Speciationof total VOC emissions was spatially and sectorally
delineated globally using the REanalysis of
TROpospheric chemical composition (RETRO)
emissions inventory, consistent with the methods
applied in Hoesly et al. (2017) for the Community
Emission Data System (CEDS) and CMIP6.
Surface O3 concentrations from GEOS-Chem were
calculated using the method outlined in Zhang
et al. (2012).
Since ModelE2 simulates its own meteorology,
three realizations of the current legislation andclimate policy scenarios were simulated, each withseparate initial conditions. Only one simulation
using GEOS-Chem was used for each time slice(2015, 2030, and 2030 with climate policy).
Additional details regarding both models, as well as
an evaluation of applicable health and agriculture
impact metrics, can be found in Seltzer et al. (2017).
2.2.2 Population exposure to ozone
Gridded estimates of O3 concentrations output
from GISS and GEOS-Chem, at 2x2.5º resolution
for 2015 and 2030 current legislation and climate
policy scenarios, were used to estimate populationweighted O3 concentrations for the four subregions, and for Asia as a whole. The proportionof the population in each region within each gridsquare was estimated based on the population
distribution in the Gridded Population of the World v3

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TABLE A2.1 POPULATION-WEIGHTED O3 CONCENTRATIONS ESTIMATED FROM THE GISSAND GEOS-CHEM MODELS
Region2015 current
legislation
baseline
populationweighted
O3 (ppb)

2030 current
legislation
baseline
populationweighted
O3 (ppb)

2030 climate
policypopulationweighted
O3 (ppb)

GISS

GEOSChem

GISS

GEOSChem

GISS

GEOSChem

East Asia

86.5

66.2

74.0

59.1

56.2

51.3

High-income
countries

77.7

53.8

73.1

48.5

57.7

43.5

South Asia

74.9

63.1

81.8

66.3

63.7

57.9

Southeast
Asia

51.2

49.7

53.0

52.2

34.5

40.9

Asia

75.4

61.7

74.4

60.8

56.4

52.3

Note: O3 exposure metric is the 6-month maximum daily maximum 1h O3 concentration.

population distribution datasets (CIESIN 2005).
From hourly O3 concentrations output separatelyfrom the GISS and GEOS-Chem models at 2x2.5o
resolution, the daily maximum one-hour (1h)concentrations were calculated. Six-month runningmean average daily maximum 1h concentrations
were then calculated, with the maximum of thesevalues being taken as the value of the O3 exposure
metric in each grid. This metric was selected tocharacterize population-weighted O3 exposurefor consistency with the metric used in the Jerrett
et al. (2009) epidemiological study that calculated
the relative risk applied to estimate O3 healthburdens (section 2.2.3). Population-weighted
O3 concentrations for each region are shown in
Table A2.1.

et al. 2016a, b; Forouzanfar et al. 2015; Lelieveld
et al. 2015; Silva et al. 2013; Lim et al. 2012).
Premature deaths associated with ozone exposure
were calculated using Equation 1:

2.2.3 Health impacts from ground-level ozone

Here, the RR (RR = 1.040; 95% CI: 1.013, 1.067) was
derived from analysis of the association between
long-term O3 exposure and respiratory mortality
in a cohort of US citizens (Jerrett et al. 2009). In
Jerrett et al. (2009), it was calculated that for a
10 ppb increase in O3 exposure, quantified as theApril-September average of the daily maximum

The health burden associated with O3 exposure
was calculated using the methodology described in
Anenberg et al. (2010), and that has been applied
extensively to estimate global ozone-associatedpremature deaths (Forouzanfar et al. 2016; Silva

154(1) ΔMort = y0(1 – exp-βΔX)Pop.
(2) RR = expβΔY
where ΔMort is the change in mortality associatedwith long-term O3 exposure, y0 is the baseline
mortality rate for respiratory diseases, Pop. is
the exposed population, ΔX is the O3 exposure
estimate, above a low-concentration cut-off, andβ is the effect estimate (natural log of the relativerisk (RR)) for the association between long-term O3
concentrations and respiratory mortality (Equation 2).

1h O3 concentration, resulted in a 4% increase inrespiratory disease among the cohort population,
who were all more than 30 years old.
The exposed populations in 2015 and 2030 weretaken from UN Population Division statistics,
and disaggregated in 5-year age groups from
25–29, 30–34, etc. up to 80+ years, in line withthe age groupings used to estimate PM 2.5associated premature mortality (UNDESA 2017).
The population in each country was distributed
according to the Gridded Population of the Worldv3 population distribution datasets (CIESIN 2005).
National, baseline respiratory mortality rates for 2015
were taken from the GBD 2016 study (Abajobir et al.
2017), as the combined disease rate from the chronic
respiratory diseases, lower respiratory infections andupper respiratory infections GBD disease categories.
To estimate future national respiratory diseasemortality rates, the 2015 respiratory disease rates
for each country was projected to 2030, based on thechange in overall death rate in each country estimatedin the UN Population Division statistics (UNDESA
2017). Hence it was assumed that the proportionof deaths from respiratory diseases remains thesame in 2030 as in 2015.
The O3 exposure metric for the population ineach 2x2.5o grid was the 6-month maximum daily
maximum 1h O3 concentration, consistent withthe exposure metric used in Jerrett et al. (2009). A
low-concentration cut-off was applied – a cut-off
below which no excess risk from O3 exposure wasassumed. This level was the minimum exposurelevel in the Jerrett et al. (2009) cohort study, andset at 33.3 ppb. Hence when the O3 concentration
in a grid was greater than 33.3 ppb, ΔX was thedifference between the O3 concentration in the grid,and 33.3 ppb. When the O3 concentration was lessthan 33.3 ppb, ΔX was set at 0 ppb.
Equation 1 was applied to estimate premature
deaths associated with O3 exposure for each age
group individually in 2015, and for the 2030 current
legislation baseline and 25 clean air measuresscenarios. Uncertainty ranges for premature
deaths, accounting for uncertainty in the effectestimates, were generated by Monte Carlosimulations. For each run, 1,000 values of RR, andhence β, were generated based on the uncertainty
range reported for the RR in Jerrett et al. (2009).
This resulted in 1,000 estimates of premature
deaths, from which 95% confidence intervals were
derived. The mean and 95% confidence intervalsof premature death estimates derived using the
GISS and GEOS-Chem O3 exposure estimated werethen calculated.
2.2.4 Vegetation impacts from ground-level ozone
The O3-induced crop loss for four staple crops,
maize, rice, soy and wheat, was estimated basedon a methodology used previously to estimate
global crop-yield loss due to O3 damage (Shindell
et al. 2012; van Dingenen et al. 2009). The equations
used to derive relative yield loss (RYL), and crop
production loss (CPL), are shown in Equations 3 and4, respectively.
(3)
Where MX = O3 exposure metric (M7 for rice and			wheat, and M12 for maize and soy)
		 RC = reference concentrationa, b = crop-specific parameters(4)
Where CPL = crop production loss
		 CP = crop production
		 RYL= relative yield loss
Crop production (year 2000 estimates), andrepresentative growing season start months wereavailable for 1x1o grids globally, as derived in van
Dingenen et al. (2009) by distributing national crop
production estimates across a country using the
global agro-ecological zones (GAEZv3) suitability
index dataset for each crop (http://gaez.fao.org/
Main.html).
The O3 exposure metrics were calculated as
the average daytime O3 concentration across a
representative 3-month growing season for eachcrop. For rice and wheat, daytime was between 09:00
and 15:59 (termed the M7 metric), and for maize andsoy it was between 08:00 and 19:59 (M12 metric).
The difference reflects the different O3 exposure

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155

metrics relevant for the concentration-response
functions applied. The hourly O3 concentrations
output from the GISS model were used to calculate
the M7/M12 metric value for each grid and eachcrop as the average daytime O3 concentration
across the growing season start month, andsubsequent two months.
Relative yield loss for each grid was then calculated
for each crop applying Equation 3, and using
the crop-specific parameters and reference
concentrations described in Table A2.2, and basedon experimentally derived relationships between

increasing O3 concentrations and crop yield loss.
Crop production loss was then calculated for eachgrid and aggregated to national- and regional-levelvalues. Uncertainty ranges for RYL and CPL, basedon the uncertainty in parameters a and b were
derived by repeating the RYL and CPL calculations
1,000 times, each time replacing a and b with avalue drawn from their probability distribution.
The mean and 95% confidence intervals of crop
production loss derived using the GISS and
GEOS-Chem ozone exposure estimated werethen calculated.

TABLE A2.2: SUMMARY OF PARAMETERS USED TO CALCULATE CROP IMPACTS

156

Crop

a (standard
error)b (standard
error)

Reference
concentration(ppb)

Reference

Maize

124 (2)2.83 (0.23)

20

Lesser et al. 1990

Rice

202 (50)

2.47 (1.10)

25

Adams et al. 1989

Soy

107 (3)

1.58 (0.16)

20

Lesser et al. 1990

Wheat

137 (6)2.34 (0.41)

25

Lesser et al. 1990

TABLE A2.3: MEASURES AND KEY FEATURES
MeasureDescription

Maximum further potential
assumed for 2030

Support to non-combustion
renewables

Increased investments
in renewable energy technology
in the power sector to replace
inefficient (mostly sub-critical)
coal-fired power stations with
non-combustion renewables(wind, solar, hydropower);
Ban of new sub-critical plants

These measures could replace
450 units (150 gigawatts (GW))
of coal power plants

Phase-out/replacementof least efficient fossil
fuel plants

Replacing coal use at the least
efficient coal plants withefficient natural gas plants

These measures could
replace 780 units (420 GW)
of coal plants

Post-combustion controls

Post-combustion control of SO2,
NOx and PM emissions of large
boilers (flue gas
desulphurization, selective catalytic reduction, dust filters) or
equivalent emission limits

All new plants after 2020

Strong push on industrial
energy efficiency

New or enhanced minimum
energy efficiency standards

A 9% reduction in energy
intensity compared to baseline,
corresponding to 160 coal
power plants (76 GW)

Post-combustion controls
for large boilers

Post-combustion control of
SO2, NOx and PM emissions oflarge boilers (flue gas
desulphurization, selective
catalytic reduction, dust filters)

All new plants after 2020
Existing plants retrofitted by
2030

Post-combustion controls
for small industries

Emission limits for SO2, NOx,
PM2.5, depending on size,
fuel and combustion process

All new plants after 2020

Industrial processes (steel,cement, etc.)

Best available techniques
required for operating permits

All plants in 2030

Brick kilns

Modernization of brick kilns(Hoffmann kilns, Zig-zag kilns,
vertical shaft brick kilns)

All new plants after 2020

Power sector

Existing plants retrofitted
by 2030

Industry

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TABLE A2.3: MEASURES AND KEY FEATURES (contd.)
MeasureDescription

Maximum further potential
assumed for 2030

Low-solvent paints,
incineration and recovery

Current practices in countriesof the Organisation for
Economic Co-operation
and Development (OECD)

Improved public transport,
urban planning

Enhanced public transportsystems, complemented bybike sharing systems, bus rapidtransit, etc. Stronger action
to decrease car ownership

By 2030, improved public
transport could reduce
10% of cars comparedto the baseline

Gasoline cars

Introduction of Euro 6-equivalentemission standards, complemented
by a maximum sulphur content
of 10 ppm

All new cars as of 2020;
no retrofits of existingvehiclesDiesel heavy-duty vehicles(trucks and buses)

Introduction of Euro 6-equivalentemission standards including diesel
particle filters, complemented by amaximum sulphur content
in diesel of 10 ppm

All new vehicles as of 2020;
no retrofits of existingvehiclesDiesel light-duty vehicles(cars and delivery vans)

Introduction of Euro 6-equivalentemission standards including diesel
particle filters, complemented bya maximum sulphur content indiesel of 10 ppm

All new cars as of 2020;
no retrofits of existing vehicles

Non-road mobile machinery

Diesel particle filters forconstruction machinery,
agricultural tractors and inlandshipping, complemented bya maximum sulphur content
in diesel of 10 ppm

All new equipment as of 2020;
no retrofits of existingmachineryTwo-wheelers

Phase-out two-stroke engine
powered vehicles; replacement by
four-stroke engines with strict
emissions standards orelectric engines

No new two-stroke engines
after 2020

Strict inspection andmaintenance (I&M)
systems

Mandatory annual I&M to identify
high-emitting vehicles and takethem off the road; this will reduce
NOx, PM and VOC emissions

Effective I&M in place in 2030

Industry (contd.)
Solvents industry, refineries

Mobile sources

158

TABLE A2.3: MEASURES AND KEY FEATURES (contd.)
MeasureDescription

Maximum further potential
assumed for 2030

Electric vehicles

Electric cars

50% of cars in 2030

Maritime shipping

Beyond the IMO agreement onsulphur content (which is part ofthe current legislation baseline);liquid natural gas;
diesel particle filters

For suitable new ships after
2020

Road paving androad cleaning

Enhanced paving and cleaningof roads and side-walks

For India, Indonesia, Iran, Nepal,
Pakistan and Sri Lanka

Mobile sources (contd.)

Residential and commercial sector
Strong push on residential
energy efficiency

New or enhanced minimum
energy performance standards
for appliances, buildings,
lighting, heating and cooling;roof-top solar installations, etc.

A 6% improvement in energy
intensity, corresponding to 110
coal power plants (48 GW)

Clean cookstoves

For cities: full access to clean
cooking fuels (natural gas,
electricity); liquefied petroleumgas (LPG) will be shifted torural areas

For cities: full access to natural
gas and electricity by 2020

For rural areas: use of LPG
and solar power; remaining
households will use advanced
cookstoves, i.e., using processedbiomass (pellets, more efficient
stoves equipped with chimneys)
Coal briquettes for cooking

For rural areas: Full universal
access to clean cooking
facilities will be achieved by
2040 (10 years later thanestablished in Sustainable
Development Goal (SDG) 7);
by 2030, 75% of current
households will use LPG;
the others advanced stoves

Replacement of chunk coal forcookstoves with briquettes

Full replacement by 2030

Collection of agricultural waste
and use for energetic purposes;
ban on open burning ofagricultural waste

Full ban enforced in 2030

Agriculture
Agricultural waste burning

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159

TABLE A2.3 MEASURES AND KEY FEATURES (contd.)
MeasureDescription

Maximum further potential
assumed for 2030

Manure management

Measures to reduce CH4 and NH3emissions from livestock production,
including anaerobic digestion,
covered storage of manure,efficient manure incorporation into
soils, feeding strategies

Application potential isrestricted by structural
factors such as farmsizes, logistics, etc.

Urea application

Efficient application of urea and/or
use of urease inhibitors; switch toammonium nitrate fertilizers
where applicable

Applicable to 50–80% of urea
use in baseline

Rice paddies

Intermittent aeration of continuously
flooded rice fields, combined withuse of low CH4 formation hybrids andsulphate containing amendments

Application to all continuously
flooded rice fields in 2030

Forest fires

Prevention and forest
management programmes,
enforcement of anti-slashand burn programmes, etc.

About 30% reduction of air
pollutant emissions in 2030

Coal mining

Pre-mining recovery of coal mine
gas and ventilation air CH4oxidation technology installedon shafts from undergroundcoal mines

All mines in 2030

Oil and gas production

Extended recovery of associatedpetroleum gas and leakage
control of fugitive emissions
from unintended leakage sources

All production in 2030

Management of solid waste

Centralized waste collection withsource separation and treatment(recycling/biogas recovery/waste i
ncineration with energy recovery),and limits on landfill disposal oforganic waste

Full source separation andwaste treatment by 2030

Residential waste burning

Centralized waste collection,
disposal/incineration, banon open burning

Full and effective ban in 2030

Agriculture (contd.)

Energy production

Waste management

160

TABLE A2.3 MEASURES AND KEY FEATURES (contd.)
MeasureDescription

Maximum further potential
assumed for 2030

Well managed two-stage(anaerobic followed by aerobic)
wastewater treatment withbiogas recovery

By 2030, all current primary
treatment facilities will be
upgraded to two-stage systems

Phase-out of consumption of
HFCs by 2050 in compliancewith the Kigali Amendment

By 2030, about one third of thelong-term potential

Waste management (contd.)
Wastewater treatment

Refrigeration
Ratification of the Kigali
Amendment to theMontreal Protocol 2016

ANNEX 2.3 CLIMATE IMPACTS
Off-line temperature calculations using the absoluteglobal temperature change potential (AGTP)
method, using the same emission estimates fromGAINS as an input, have been used to estimate
the relative influence of different Asian emission
scenarios on global temperature. The results
are shown in Figure A2.9, where the impact on
temperature of the mitigation scenario for different
groups of substances, which aims to reduce air
pollution in Asia while maximizing the contribution
to achieving SDGs, is shown in relation to thetemperature change in the baseline scenario.
The results are also shown for subsets of substancesgrouped according to those substances that cool
the climate (SO4, NOX, and NH3) and short-lived
climate pollutants (SLCPs) that warm the climate(BC along with its co-emissions, and CH4). It canbe seen that the net average change in temperature
is a reduction in warming (brown line), which is
supported by the GCM runs, although the more
simple climate calculations using AGTP show achange in warming of ~0.15ºC 10 years earlier
than using the GCM (Figure A2.10). However,using these calculations it can be seen that the air
quality strategies reduce emissions of both coolingcomponents and warming components. Differences
between the sum of responses to cooling aerosols
plus SLCPs and the total mitigation are attributable

to CO2 and HFCs. These finding are in line with thoseof the UNEP/World Meteorological Organizationassessment in 2011. Additionally, Figure A2.9
shows the importance on concentrating on SLCP
strategies alongside air quality strategies, and CO2
strategies. This is because SO2 will be reduced toprotect air quality and as a result of a shift awayfrom coal and oil, and to compensate for the
potential increase in warming from the reduction ofthis cooling component in at the atmosphere, it isvery important to concentrate efforts at the sametime to promote reductions in short-lived warming
components – primarily BC and CH4.
The GISS Global Climate Model has also been run
with the International Institute for Applied Systems
Analysis (IIASA) emission baseline and mitigation
scenario, with an ensemble of three simulations
performed over a long period from 2006 to 2054,
and the average result of the mitigation scenario
relative to the baseline is shown in Figure A2.10.
This figure shows the resulting global temperaturechange of mitigating air pollution (specifically PM2.5),
CO2 (according to the policy scenario from IIASA),
and other greenhouse gases such as CH4 and HFCs,
relative to the baseline scenario. Initially there seems
to be a slight increase in global temperature, although
this is not a significant change, and then there is asignificant decrease in global temperature by 2050,
of about 0.2ºC, which is a substantial reduction in
global temperature over this time frame for emission

AIR POLLUTION IN ASIA AND THE PACIFIC: SCIENCE-BASED SOLUTIONS

161

changes in only one world region. The initial warming
is consistent with prior studies looking at the
impact of measures controlling large-scale energy
and transport sector emissions that affect both
short-lived cooling agents and long-lived warming
agents (Shindell et al. 2016; Raes and Seinfeld 2009).

Similarly, as the cooling aerosols that are reducedby the policies are predominantly local whereas the
reductions in the greenhouse gases CO2 and CH4
are spread worldwide, the climate benefits in termsof reduced warming tend to be weakest over Asia
itself (Figure A2.11). Similar results were found for

0.5

Temperature (°C)

0.4

0.3

0.2

0.1

0.0
2018

2022

2026
Baseline

2030

2034

2038

Mitigation

0.10

Temperature (°C)

0.05
0.00
-0.05
-0.10
-0.15
-0.20
-0.25
2015

2020

2025
SO2+NOx+NH3

2030

2035

2040

SLCP

Note: Impacts of all substances acting together are shown in the upper panel (except VOCs, which are not well-suited to
the AGTP analysis), whereas the impact of the cooling substances primarily associated with power generation, industry
and gasoline-powered vehicles, and of SLCPs (BC, OC and CO primarily from incomplete combustion of residential fuelsand diesel vehicles, and CH4 (but not HFCs)) are grouped together and compared in the lower panel.

FIGURE A2.8 IMPACT OF THE AIR POLLUTION AND SUSTAINABLE DEVELOPMENT GOALATTAINMENT MITIGATION SCENARIO ON WARMING, ESTIMATED
USING ABSOLUTE GLOBAL TEMPERATURE POTENTIALS

162

United States policies that simultaneously reduce
long-lived greenhouse gases and short-lived cooling
aerosols (Shindell et al. 2016). The exception in
the case of Asia is the Himalayan/Tibetan Plateau
region, where, owing to the strong snow/ice albedo
effects of reductions in BC deposited on the surface
as well as the greater importance of BC relative tocooling aerosols over bright surfaces, there is asignificant local cooling (Figure A2.11). This has thepotential to substantially reduce melting of glaciersin this region. It should also be noted that although
the climate benefits of action taken to reduce bothcooling aerosols and long-lived warming greenhousegases is in general weakest in a region taking action
on its own, such actions taken broadly across major

regions of the world would lead to everywhere
receiving benefits, as the global greenhouse gas
benefits from multiple regions would outweigh thelocal disbenefits of reductions in cooling aerosols –in addition, of course, to the large local public healthbenefits in regions that reduce cooling aerosols.
The temperature change in Figure A2.10 is the net
result of changes in all of the emissions affecting
atmospheric temperature. Given that we were
only able to run the GCM for two scenarios (thecurrent legislation baseline and the 25 clean air
measures scenario) it was not possible to show
the relative impact of abating different sources andsubstances in a number of different scenarios.

global mean surface temperature
anomaly (°C)

0.2

0.1

0

-0.1

-0.2

-0.3
2006

2012

2018

2024

2030

2036

2042

2048

2054

2006

2012

2018

2024

2030

2036

2042

2048

2054

global mean surface temperature
anomaly (°C)

0.2

0.1

0

-0.1

-0.2

-0.3

Note: Eight-year running mean values are shown for the ensemble mean (top) and for the three individual ensemble
members (bottom).

FIGURE A2.9: GLOBAL MEAN SURFACE TEMPERATURE CHANGE DUE TO THE MITIGATIONSCENARIO RELATIVE TO THE BASELINE SCENARIO (ºC) BETWEEN 2015 AND 2054

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-1.9 -0.36 -0.28 -0.2 -0.12 -0.04 0.04 0.12 0.2 0.28 0.36 0.51
Note: The stripes indicate significant changes (95 per cent confidence).
Note: Hatching indicates values that are statistically significant at the 95% confidence level.

FIGURE A2.10 GEOGRAPHIC PATTERN OF ANNUAL AVERAGE
SURFACE TEMPERATURE RESPONSE TO IMPLEMENTATION OF THE
25 CLEAN AIR MEASURES, AVERAGED OVER THE THREE ENSEMBLE
MEMBERS FOR THE 2046–2054 DECADE164

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166

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Abbreviations
AAP

Ambient air pollution

CEDS

Community Emission Data System

AATH

ASEAN Agreement on 			

CF

Charcoal-filtered air

Transboundary Haze Pollution

CFC

Chlorofluorocarbon

ADB

Asian Development Bank

CH4

MethaneAECEN

Asian Environmental Compliance 		

CLE

Current legislation scenario

and Enforcement Network

CNG

Compressed natural gas

Absolute Global Temperature

CO

Carbon monoxide

Change Potential

CO2

Carbon dioxide

Al

Aluminium

COPD

Chronic obstructive pulmonary 		

ALRI

Acute lower respiratory infection

AOT40

Accumulated ozone exposure over

CPL

Crop production lossa threshold of 40 parts per billion

CTMs

Chemistry transport models

Accumulated ozone exposure over

DALYs

Disability-adjusted life years

a threshold of 60 parts per billion

DEAD

Dust entrainment and deposition

APCAP

Asia Pacific Clean Air Partnership

DECAs

Domestic emission control areas 		

APERC

Asia Pacific Energy Research Centre

AQI

Air Quality Index

ASEAN

Association of Southeast Asian 		

AGTP

AOT60

disease(China)DO3SE

Deposition of Ozone for Stomatal
Exchange model

Nations

EDU

Ethylene diurea

ATS

Active tobacco smoking

EIU

Economist Intelligence Unit

BC

Black carbon

EMEP

European Monitoring and 		

BEE

Bureau of Energy Efficiency (India)

BenMAP

Environmental Benefits Mapping

F-gas

Fluorinated gas

and Analysis Program of the 		

FACE

Free air concentration enrichment

USEPA

FAO

Food and Agriculture OrganizationBP

BP plc (formerly British Petroleum)

BrC

Brown CarbonoDegree Celsius

C

Evaluation Programmeof the United Nations
GAINS

Greenhouse gas – Air pollution 		Interactions and Synergies model

GAEZ

Global agro-ecological zones

Initiative for Asian Cities)

GBD

Global burden of disease

Chinese Academy of Sciences 		

GCM

General circulation model(China)GCM

Global climate model

CaCO3

Calcium carbonate

GDP

Gross domestic product

CC

Closed chamber

GEOS-Chem

Goddard Earth Observing System-

CCAC

Climate and Clean Air Coalition		CAA (CAI-Asia) Clean Air Asia (formerly Clean Air 		
CAS

CDM

chemical transport model(UN Environment)

GFED

Global Fire Emissions Database

Clean Development Mechanism

GHG

Greenhouse gas

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GISS

Goddard Institute for Space Studies

GMAO

Global Modelling and Assimilation

Project for Promotion of Regional

OfficeInitiative on Solid Waste 			

GMI

Global Methane Initiative

Management, Phase II (Japan)

GW

Gigawatt (109 watts)

km2

Square kilometre

GWP

Global warming potential

kt

Kilotonnes (103 tonnes)

HAPHousehold air pollutionkWhkilowatt (103 watts)-hour

HCFC

Hydrochlorofluorocarbon

LC

Lung cancer

HFC

Hydrofluorocarbon

LDAR

Leak detection and repair system

HEI

Health Effects Institute

LPG

Liquefied petroleum gas

HKHT

Hindu Kush, Karakoram, Himalaya

m2

square metre

and Tibet

m3

cubic metre

HOx

Hydrogen oxides radicals

MEE

Ministry of Ecology and 			

I&M

Inspection and maintenance 		
programmes

ICCT

ICRAF

MFR
mg/m2
MICS-Asia

International Energy Agency

IER

Integrated exposure-response

IGES

Institute for Global Environmental

MMTs

Ischemic heart disease

IHME

Institute for Health Metrics and 		

IIASA

MODIS

Moderate Resolution Imaging 		Spectroradiometer

MoEF

Ministry of Environment and Forest(India)MoEF&CC

Ministry of Environment, Forest 		and Climate Change (India)

Evaluation

Mt

Million (106) tonnes

International Institute for Applied 		

M77-hour seasonal daytime mean 		

Systems Analysis

measured ozone concentration

IMO

International Maritime Organization

N

Nitrogen

IPCC

Intergovernmental Panel on 		

NAMP

National Air Quality Monitoring 		Climate Change
IPCC SRES A2 IPCC Special Report on Emission 		

Programme (India)
NASA

Scenarios A2
JICA

Japan International Cooperation 		
Agency208

Multi‐partite monitoring teams 		
(Philippines)

Strategies
IHD

Model Inter-Comparison Study
for Asia

for Research in AgroForestry)
IEA

Milligrams (0.001 grams) per 		square metre

World Agroforestry Centre 		(formerly International Centre

Maximum technically feasible 		reduction

International Council for Local 		
Environmental Initiatives

Japanese Technical Cooperation 		

Environment (China)

International Council on Clean 		
Transport

ICLEI

J-PRISM II

National Aeronautics and Space 		Administration (USA)NBCI

National Biomass Cookstoves 		
Initiative (India)

NDC

Nationally determined contribution

PPM

Primary particulate matter emissions

NEDO

New Energy and Industrial 		ppm

Parts per million (106)Technology Development

ppm.h

The product of parts per million

Organization (Japan)

and hours

NH3

Ammonia

NH4+

Ammonium

NISP

National Improved Stove Program 		PV

Photovoltaic(China)RC

Reference concentration

Non-methane volatile organic 		

RETRO

REanalysis of TROpospheric 		

NMVOC

PSI

Pollutants Standard Index 			(Singapore)compoundchemical composition

NO

Nitrogen monoxide

RR

Rate ratios of excess mortality

NOx

Nitrogen oxides (NO and NO2)

RR

Relative risk

NO2

Nitrogen dioxide

RYL

Relative yield loss

NO3-

NitrateS

Sulphur

N2O

Nitrous oxide

SDG

Sustainable Development Goal

NPIC

National Programme for Improved

SEI

Stockholm Environment Institute

Chulhas (India)

SF6

Sulphur hexafluoride

Natural Resources Defence

SGFE

Sustainable Green Fuel Enterprise 		

NRDC

Council (USA)programme (Cambodia)OC

Organic carbon

SHS

Second-hand tobacco smoke

OECD

Organisation for Economic 		

SIDS

Small Island Developing States

Co-operation and Development

SLCP

Short-lived Climate Pollutant, i.e.,

OH

Hydroxyl radical

Black carbon, methane,

OTC

Open-top chamber

tropospheric ozone and 			

O3

Ozone

hydrofluorocarbons

P

Phosphorus

PAH

Polycyclic aromatic hydrocarbon

PAN

Peroxyacyl nitrates

SOA

Secondary organic aerosols

PFC

Perfluorocarbon

SO2

Sulphur dioxide

PM

Particulate matter

SO42-

Sulphate

PM2.5

Particulate matter with an 			

SPREP

Secretariat of the Pacific Regional 		

SMG(Republic of Korea)

aerodynamic diameter of equal toand less than 2.5 micrometres (µm)
PM10Seoul Metropolitan Government 		

Environment Programme
SVPCF

Particulate matter with an 			Special Vehicle Pollution Control 		Fund (Philippines)

aerodynamic diameter of equal to

TAA

Total amino acids

and less than 10 micrometres (µm)

TEAA

Total essential amino acids

POPs

Persistent organic pollutants

TEG

Triethylene glycol

ppb

Parts per billion (109)

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TLB
TLFF
TLGF

Tropical Landscapes Bond 		µg

Microgram(Indonesia)µg/m3

Micrograms per cubic metre

Tropical Landscapes Finance 		µm

Micrometre

Facility (Indonesia)

1h

One hour

Tropical Landscapes Grant Fund 		%Per cent(Indonesia)
TLLF

Tropical Landscapes Loan Fund 		(Indonesia)

TNEAA

Total non-essential amino acids

TWh

Terawatt (1012 watts) hours

UITP

International Association of Public 		
Transport (India)

UN

United Nations

UNCCD

United Nations Convention to 		
Combat Desertification

UNCRD

United Nations Centre for Regional
Development

UNEA

United Nations Environment 		
Assembly

UNEP

United Nations Environment
Programme (UN Environment)

UNESCAP

United Nations Economic and Social
Commission for Asia and the Pacific

UNESCO

United Nations Educational, 		
Scientific and Cultural Organization

UNFCCC

United Nations Framework 		
Convention on Climate Change

US EPA

US Environmental Protection 		
Agency (USA)

VOC

Volatile organic compound

WEO

World Energy Outlook

WHO

World Health Organization

WHR

Waste heat recovery

WMO

World Meteorological Organization

WWAPWorld Water Assessment 			Programme (UNESCO)

UASB

210

Upflow anaerobic sludge blanket

Glossary
TermDefinition

Absorption

The process in which the energy of radiation, e.g. light, is taken up by
matter. In this process, the electromagnetic energy is transformed to otherforms of energy, e.g. to heat.

Accumulated ozone (O3)
exposure over a threshold(AOT) 40

Accumulated O3 exposure over a threshold of 40 parts per billion (ppb),
equivalent to 80 micrograms per cubic metre (µg/m3), for vegetation is theaccumulated excess of hourly ozone concentrations above 40 ppb during a
relevant growing season.

Acidification

Change in the environment’s natural chemical balance caused by an increasein the concentration of acidic elements. Acidic atmospheric deposition(sometimes termed acid rain) can acidify soils and aquatic ecosystems withlow capacity to buffer incoming acidity.

Acid rain

Rain having a pH less than 5.6. The acidity is often the result of pollution
caused mostly by SOx and NOx that are discharged into the atmosphereby industry. It is also created by burning coal and oil, from the operationof smelting industries and from transport. In the atmosphere, these gases
combine with water vapour to form acids, which then fall back to Earth in rain.

Aerosols

A collection of airborne solid or liquid particles (excluding pure water),with a typical size between 0.01 and 10 micrometers (µm) and residingin the atmosphere for at least several hours. Aerosols may be of either
natural or anthropogenic origin. Aerosols may influence climate in two
ways: directly through scattering and absorbing radiation, and indirectly
through acting as condensation nuclei for cloud formation or modifying
the optical properties and lifetime of clouds.

Albedo or surface albedo

The fraction of solar radiation reflected by a surface or object, often expressed
as a percentage. Snow-covered surfaces have a high albedo, the albedo ofsoils ranges from high to low and vegetation-covered surfaces and oceans
have a low albedo. The Earth’s planetary albedo varies mainly due to varying
cloudiness, snow, ice, leaf area and land cover changes.

Ambient air quality
monitoring

The systematic, long-term assessment of pollutant levels by measuring thequantity and types of certain pollutants in the surrounding outdoor air. The usual
substances monitored include dust deposition, O3, PM10, PM2.5, NOx and SOx.

Anaerobic
digestion

A series of processes in which microorganisms break down biodegradable
material in the absence of oxygen. It is commonly used for industrial ordomestic purposes to manage waste and/or to release energy.

Anthropogenic

Made by people or resulting from human activities.

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Term

Definition

Atmospheric chemistry

The study of the chemical composition and transformations of thenatural planetary atmosphere. It focuses upon understanding natural andanthropogenic emissions to the atmosphere, the transport, chemical andphysical transformations of atmospheric constituents, and the effects of air
pollution and atmospheric chemistry on the environment and, particularly,
on human health.

Atmospheric deposition

The transfer of substances in air to surfaces, including soil, vegetation, surface
water and indoor surfaces, by dry or wet processes.

Atmosphere

The gaseous envelope surrounding the Earth.

Atmosphericforcing

The difference in the radiative forcing at the top-of-the-atmosphere or
tropopause and at the surface, representing heat absorbed in the lower
atmosphere. Gradients in heating from one place to another drive winds,and so regional differences in atmospheric forcing are closely connected tochanges in regional circulation and precipitation.

Baseline

The state against which change is measured. A baseline period is the period
relative to which different scenarios can be compared.

Baseline scenario

The baseline (or reference) is the state against which change is measured.
It might be a current baseline, in which case it represents observable,
present-day conditions. It might be a future baseline, which is a projected
future set of conditions excluding the driving factor of interest. Alternativeinterpretations of the reference conditions can give rise to multiple baselines.

Biodiversity

Shorthand for biological diversity. Variability among living organisms fromall sources including terrestrial, marine and other aquatic ecosystems, andthe ecological complexes of which they are part; this includes diversity
within species, between species and of ecosystems.

BiofuelBiofuels are non-fossil fuels. They are energy carriers that store the energy
derived from organic materials (biomass), including plant materials andanimal waste.

BiogasBiogas typically refers to a gas produced by the biological breakdown oforganic matter in the absence of oxygen. Biogas originates from biogenic
material and is a type of biofuel. Biogas is produced by anaerobic digestion or
fermentation of biodegradable materials such as biomass, manure, sewage,
municipal waste, green waste, plant material and energy crops.

Biogenic

A biogenic substance is a product made by or of life forms. The term
encompasses constituents, secretions, and metabolites of plants
or animals.

Biomass

In the context of energy, the term biomass is also often used to refer toorganic materials, such as wood by-products and agricultural wastes, which
can be burned to produce energy or converted into a gas and used for fuel.

TermDefinition

Biosphere

The worldwide sum of all ecosystems. The zone of life on Earth, a closed
system, apart from solar and cosmic radiation and heat from the interior of
the Earth, and largely self-regulating.

Black carbon (BC)The substance formed through the incomplete combustion of fossil fuels,
biofuels, and biomass, which is emitted in both anthropogenic and naturally
occurring soot. It consists of pure carbon in several linked forms. Black
carbon warms the Earth by absorbing heat in the atmosphere and by reducing
albedo – the ability to reflect sunlight – when deposited on snow and ice.
Operationally defined as an aerosol species based on measurement of lightabsorption and chemical reactivity and/or thermal stability.

Brown clouds

High concentrations of particulate matter suspended in the atmosphere leadto light scattering, resulting in a reduction in visibility and a reddish-brownsky colouration.

Business-as-usual
scenario

The scenario that examines the consequences of continuing current trends
in population, economy, technology and human behaviour.

Bus rapid transit

A term applied to a variety of public transport systems using buses toprovide faster, more efficient service than an ordinary bus line. Often thisis achieved by making improvements to existing infrastructure, vehicles
and scheduling.

Carbon cycle

All parts (reservoirs) and fluxes of C. The cycle is usually thought of as
four main reservoirs of carbon connected by pathways of exchange. The
reservoirs are the atmosphere, terrestrial biosphere (usually including
freshwater systems), oceans, and sediments (including fossil fuels).
The annual movements of C, the C exchanges between reservoirs, occur
because of various chemical, physical, geological, and biological processes.
The ocean contains the largest pool of C near the surface of the Earth, but
most of that pool is not involved with rapid exchange with the atmosphere.

Carbon dioxide (CO2)equivalent

Carbon dioxide equivalent describes how much global warming a given
type and amount of greenhouse gas may cause, using the functionallyequivalent amount or concentration of CO2 as the reference.

Carbon dioxide (CO2)
fertilization

The enhancement of the growth of plants as a result of increased atmospheric
CO2 concentration. Depending on their mechanism of photosynthesis,
certain types of plants are more sensitive to changes in atmospheric
CO2 concentration.

Carbonsequestration

The uptake and storage of C. Trees and plants, for example, absorb CO2,
release the O and store C.

Carbon sink

A C sink is a natural or artificial reservoir that accumulates and stores some
C-containing chemical compounds for an indefinite period.

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Term

Definition

Carbonaceous
aerosol

Aerosol consisting predominantly of organic substances and various formsof BC.

Carbonaceous species

Species consisting predominantly of organic substances and various formsof BC. Carbonaceous species are an important contributor to the massconcentration of fine particulates (PM2.5).

Cardiopulmonary

Having to do with the heart and lungs.

Cardiovascular disease

The class of diseases that involve the heart or blood vessels.

Chronic (medicine)

In medicine, a chronic disease is a disease that is long lasting or recurrent.

Climate change

The long-term fluctuations in temperature, precipitation, wind and all otheraspects of the Earth’s climate. It is also defined by the United Nations
Framework Convention on Climate Change as “change of climate which is
attributed directly or indirectly to human activity that alters the compositionof the global atmosphere and which is in addition to natural climate
variability observed over comparable time periods”.

Chlorofluorocarbons(CFCs)

Any of several organic compounds composed of C, fluorine (F), chlorineCl) and hydrogen (H). They were formerly used widely as refrigerants,
propellants, and cleaning solvents.

Clean development
mechanism (CDM)

One of the three market-based mechanisms under the Kyoto Protocol to theUnited Nations Framework Convention on Climate Change (UNFCCC) whereby
developed countries may finance greenhouse gas emissions-avoiding
projects in developing countries, and receive certified emission reduction
credits for doing so. These may be applied towards meeting mandatory
limits on their own emissions.

Co-benefits

The positive effects that a policy or measure aimed at one objective might
have on other objectives, without yet evaluating the net effect on overallsocial welfare. Co-benefits are often subject to uncertainty and depend
on, among others, local circumstances and implementation practices.
Co-benefits are often referred to as ancillary benefits.

Cohort study (long term)

A type of medical research to investigate the causes of disease and toestablish links between risk factors and health outcomes by observing large
groups of individuals and recording their exposure to certain risk factors tofind clues as to the possible causes of disease. The word cohort means agroup of people. These types of studies can be forward-looking (prospective)
or backward-looking (retrospective). Prospective studies are plannedin advance and carried out over a future period of time. Retrospective studies
look at data that already exist and try to identify risk factors for particularconditions. Interpretations are limited because the researchers cannot goback and gather missing data. These long-term studies are sometimes calledlongitudinal studies.

TermDefinition

Compliance

A term that helps describe whether and to what extent there is adherence toan order, rule or agreement. Compliance depends on implementing policies
agreed, and on whether measures are introduced to follow up on policies.
Compliance is the degree to which the actors whose behaviour is targetedby the agreement, local government units, corporations, organizations or
individuals, conform to the implementing obligations.

Compliance incentives

The financial means, directly or indirectly, to motivate polluters to adhere to
the provisions in regulation, policy or law.

Concentration response
function

See Dose-response function.

Conventional measures

Emission control actions that have been in use for a long time on frequently
targeted sources of emissions such as power plants or vehicles.

Cost-benefit study/analysis

Cost-benefit study/analysis is an economic evaluation technique in which
both the costs and values of all benefits and consequences from different
interventions are expressed in monetary units. The purpose is to inform adecision on whether to make a change and the costs associated with it.

Cross-cutting issue

An issue that cannot be adequately understood or explained without
reference to the interactions of several dimensions that are usually treatedseparately for policy purposes. For example, in some environmental problems
economic, social, cultural and political dimensions interact with one another.

Cost effectivenessan economic analysis that compares the relative costs and outcomes (effects)of different courses of action.

Crop residues

There are two types of agricultural crop residues. Field residues arematerials left in an agricultural field or orchard after the crop has been
harvested. These residues include stalks and stubble (stems), leaves,roots and seed pods. Process residues are those materials left after theprocessing of the crop into a usable resource. These residues include
husks, seeds, bagasse, and roots.

CryosphereThat portion of the Earth where natural materials (water, soil, etc.) occur infrozen form.

Cultivar

A cultivar is a cultivated variety of a plant that has been deliberately selected
for specific desirable characteristics such as the colour and form of theflower, yield of the crop, disease resistance, etc.

Decoupling

Decoupling means removing the link between two variables. For example,
resource decoupling is the delinking of economic growth and resource use
and impact decoupling is the delinking of economic growth and negativeenvironmental impacts. Decoupling can be relative, e.g. the rate of resource
use increase is lower than the rate of economic growth, or absolute, e.g.
resource use declines while the economy grows.

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Term

Definition

Deforestation

Conversion of forested land to non-forest areas as a direct result of
human activities.

Diesel particle
filter (DPF)

A device designed to remove diesel particulate matter or soot from theexhaust gas of a diesel engine.

Disability-adjusted life
years (DALYs)

The sum of years of potential life lost due to premature mortality andthe years of productive life lost due to disability. It was developed so that
non-fatal outcomes could be considered alongside mortality in theprioritization of health resources. DALYs have been used to assess themagnitude of disease, health risks and premature death both globally andat national and local levels. It can be referred to as a measurement of
the gap between the current health status and an ideal health situation
where the entire population lives to an advanced age, free of disease
and disability – 1 DALY is equivalent to the loss of one healthy life year.

Discounting

Discounting is a financial mechanism in which a debtor obtains the right todelay payments to a creditor for a defined period of time in exchange for acharge or fee. Essentially, the party that owes money purchases the right todelay payment until some future date. The discount, or charge, is simply thedifference between the original amount owed and the amount that has tobe paid in the future to settle the debt.

Dose-response
function

Describes the change in effect on an organism caused by differing levelsof exposure (or doses) to a stressor (usually a chemical) after a certain
exposure time.

Drylands

Areas characterized by lack of water, which constrain two major, linked
ecosystem services: primary production and nutrient cycling. Four dryland
sub-types are widely recognized: dry sub-humid, semi-arid, arid and hyper-arid,
showing an increasing level of aridity or moisture deficit. Formally, thisdefinition includes all land where the aridity index value is less than 0.65.

Ecosystem

A dynamic complex of plant, animal and micro-organism communities andtheir non-living environment, interacting as a functional unit.

Ecosystem services

The benefits people obtain from ecosystems. These include provisioning
services, such as food and water, regulating services, such as flood anddisease control, cultural services, such as spiritual, recreational and cultural
benefits, and supporting services, such as nutrient cycling, that maintainthe conditions for life on Earth.
In issues of water quality, refers to liquid waste (treated or untreated)discharged to the environment from sources such as industrial process andsewage treatment plants.

Effluent

216

Emission inventory

Details the amounts and types of pollutants released into the environment.

Emission factor

A unique value for scaling emissions to activity data in terms of a standard
rate of emissions per unit of activity.

Term

Definition

Emission standard

The maximum amount of discharge legally allowed from a single mobile or
stationary source.

End-of-pipe measures

Methods or technologies used to remove already formed contaminantsfrom a stream of air, water, waste, or other product. These techniques arecalled ‘end-of-pipe’ as they are normally implemented as a last stage of aprocess before the stream is disposed of or delivered such as scrubbers on
smokestacks and catalytic convertors on automobile tailpipes that reduce
emissions of pollutants after they have formed.

Energy efficiency

Refers to actions to save fuels by, for example, better building design, themodification of production processes, better selection of road vehicles andtransport policies, the adoption of district heating schemes in conjunction withelectrical power generation, and the use of domestic insulation and double
glazing in homes.

Energy intensity

Ratio of energy consumption and economic or physical output. At thenational level, energy intensity is the ratio of total domestic primary energy
consumption or final energy consumption to gross domestic product orphysical output. Lower energy intensity shows greater efficiency in energy use.

Enteric
fermentation

A digestive process by which carbohydrates are broken down by
microorganisms into simple molecules for absorption into the bloodstreamof an animal. It is one of the factors in increased CH4 emissions.

Episode (air pollution)

A period of abnormally high concentrations of air pollutants, often due to low
winds and temperature inversion, that can cause illness and/or death.

Eutrophication

The enrichment of an ecosystem with chemical nutrients, typically compounds
containing N, P or both. Eutrophication can be a natural process in lakes,
occurring as they age through geological time. Human activities can accelerate
the rate at which nutrients enter ecosystems. The runoff from agriculture anddevelopment, pollution from septic systems, sewers and other human-related
activities increase the flux of both inorganic nutrients and organic substances
into terrestrial, aquatic, and coastal marine ecosystems (including coral reefs).
Eutrophication is a leading cause of impairment of many freshwater andcoastal marine ecosystems in the world.

Fertilization effect (CO2)

See Carbon dioxide (CO2) fertilization.

Flue gas desulphurization(FGD)

A technology that employs a sorbent, usually lime or limestone, to remove
sulfur dioxide SO2 from the gases produced by burning fossil fuels. Flue gas
desulfurization is a current state-of-the art technology for major SO2 emitters,
like such as power plants.

Food security

The 1996 World Food Summit of 1996 defined food security as existing“when all people at all times have access to sufficient, safe, nutritious food tomaintain a healthy and active life”.

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Term

Definition

Free air concentrationenrichment (FACE)

A method used by ecologists and plant biologists that raises the concentrationof a gas of interest, such as CO2 or O3, in a specified area and allows the
response of plant growth to be measured. Experiments using FACE are required
because most studies looking at the effect of elevated CO2 concentrations
have been conducted in laboratories and where there are many missing
factors including plant competition. Measuring the effect of elevated CO2
and O3 using FACE is a more natural way of estimating how plant growth
will change in the future as the CO2 the concentration of these gases may
rises in the atmosphere. FACE also allows the effect of elevated CO2 pollutant
concentrations on plants that cannot be grown in small spaces, such as trees,
to be measured. FACE experiments, however, carry significantly higher costs
relative to greenhouse experiments.

Fossil fuels

Coal, oil, petroleum, natural gas and other hydrocarbons are called fossil fuels
because they are made of fossilized, carbon-rich plant and animal remains.
These remains were buried in sediments and compressed over geologic time,slowly being converted to fuel.

Fugitive emissions

Emissions of gases or vapours from pressurized equipment due to leaks andother unintended or irregular releases, mostly from industrial activities – e.g.
emissions of CH4 escaping from oil and gas extraction not caught by a capturesystem. As well as the economic cost of lost commodities, fugitive emissions
contribute to air pollution and climate change.

Fuel switching

The substitution of one energy source for another in a particular end use orprocess, as a result of changing relative prices or technologies.

Global burden of disease(GBD)

A comprehensive demographic and epidemiological framework to estimate
health gaps for an extensive set of causes of disease and injury, and for
major risk factors, using all available mortality and health data and methods
to ensure internal consistency and comparability of estimates.

General circulation
model (GCM)

A global, three-dimensional computer model of the climate system which
can be used to simulate human-induced climate change. GCMs arehighly complex and they represent the effects of such factors as reflective
and absorptive properties of atmospheric water vapour, greenhousegas concentrations, clouds, annual and daily solar heating, ocean
temperatures and ice boundaries. The most recent GCMs include global
representations of the atmosphere, oceans, and land surface.

Global dimming

The gradual reduction in the amount of global direct irradiance at the Earth’s
surface that was observed for several decades after the start of systematic
measurements in the 1950s. It is thought to have been caused by an increase inparticulates such as sulphate aerosols in the atmosphere due to human action.

Global mean (surface)temperature

An estimate of the global mean surface air temperature. For changes overtime, however, only anomalies, such as departures from a climatology, areused, most commonly based on the area-weighted global average of the sea
surface temperature anomaly and the land surface air temperature anomaly.

TermDefinition

Global warming

Global warming is an average increase in the temperature of the atmospherenear the Earth’s surface and in the troposphere, which can contribute tochanges in global climate patterns. Global warming can occur from a varietyof causes, both natural and human induced. In common usage, global warming
often refers to the warming that can occur as a result of increased emissionsof greenhouse gases from human activities.

Global temperaturechange potential (GTP)

The ratio of the temperature change caused by emitting 1 kilogram (kg) of
the species at the end of the period considered, to that caused by emitting
1 kg of CO2.

Global warming potential(GWP)

The global warming potential of a gas or particle refers to an estimate of thetotal contribution to global warming over a particular time that results fromthe emission of 1 unit of that gas or particle relative to 1 unit of the referencegas, CO2, which is assigned a value of 1. An index representing the combined
effect of the differing times greenhouse gases remain in the atmosphere andtheir relative effectiveness in absorbing outgoing infrared radiation.

Governance

The manner in which society exercises control over resources. It denotes
the mechanisms through which control over resources is defined andaccess is regulated. For example, there is governance through the state, themarket or through civil society groups and local organizations. Governanceis exercised through institutions, laws, property rights systems andforms of social organization.

Greenhouse gases (GHGs)

Gaseous constituents of the atmosphere, both natural and anthropogenic,
that absorb and emit radiation at specific wavelengths within the spectrumof infrared radiation emitted by the Earth’s surface, the atmosphereand clouds. This property causes the greenhouse effect. Water vapour(H2O), CO2, N2O, CH4 and O3 are the primary greenhouse gases in the
Earth’s atmosphere. There are also human-made greenhouse gases in
the atmosphere, such as the halocarbons and other Cl and bromine (Br)containing substances. Beside CO2, N2O and CH4, the Kyoto Protocol deals
with sulphur hexafluoride (SF6), HFC and PFC gases in the Earth’s atmosphere.

Gross domestic product(GDP)

The sum of gross value added, at purchasers’ prices, by all resident andnon-resident producers in the economy, plus any taxes and minus any
subsidies not included in the value of products in a country or geographic region
for a given period, normally one year. Gross domestic product is calculated
without deductions for depreciation of fabricated assets or depletion anddegradation of natural resources.

Groundwater

Water that flows or seeps downward and saturates soil or rock, supplying springs
and wells. The upper surface of the saturated zone is called the water table.

Haze

A state of atmospheric obscurity due to the presence of fine dust particles insuspension.

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Term

Definition

High-emitting
vehiclesPoorly tuned or defective vehicles with emissions of particulate matter manytimes greater than the average.

Hoffmann kiln

The most common kiln used in brick production. A Hoffmann kiln consists ofa main fire passage surrounded on each side by several small rooms whichcontain pallets of bricks. Each room is connected to the next by a passageway
carrying hot gases from the fire. This design makes for a very efficient useof heat and fuel.

Human well-being

The extent to which individuals have the ability to live the kinds of lives
they have reason to value; the opportunities people have to achieve their
aspirations. Basic components of human well-being include: security, material
needs, health, education and social relations.

Hybrids or hybrid vehicles

A hybrid vehicle use two different forms of power, such as an electric motor
and an internal combustion engine, or an electric motor with a battery andfuel cells for energy storage. The basic principle is that the different motors
work better at different speeds; the electric motor is more efficient at
producing torque or turning power while the combustion engine is better for
maintaining high speeds. Switching from one to the other yields greater fueland energy efficiency with less consumption of fuel and fewer CO2 emissions
than a comparable conventional petrol or diesel-engined vehicle. All hybrids
have the ability to generate electric current, store it and use that current tohelp drive the car.

Hydrocarbons

Substances containing only H and C.

Hydrochlorofluorocarbons(HFCs)

Organic compounds that contain F and H atoms and are the mostcommon type of organofluorine compounds. They are frequently usedin air conditioning and as refrigerants in place of the older CFCs suchas R-12 and HCFCs such as R-21. They do not harm the O3 layer as much as
the compounds they replace, but they do contribute to global warming.

Hydrological cycle

Succession of stages undergone by water in its passage from the atmosphereto the Earth and its return to the atmosphere. The stages include evaporationfrom land, sea or inland water; condensation to form clouds; precipitation;
accumulation in the soil or in water bodies; and re-evaporation.

Incomplete
combustion

A reaction or process which entails only partial burning of a fuel. Combustionis almost always incomplete and this may be due to a lack of oxygen or low
temperature, preventing the complete chemical reaction.

Indoor air pollution(or household air pollution)

Air pollutants that occur within buildings or other enclosed spaces, as opposedto those occurring in outdoor, or ambient, air. Some examples of indoor air
pollutants are NOx, smoke, formaldehyde (CH2O), and CO. The air quality
within and around buildings and structures, especially as it relates to the healthand comfort of building occupants. Understanding and controlling common
pollutants indoors can help reduce your risk of indoor health concerns. HealthTermDefinition
effects from indoor air pollutants may be experienced soon after exposureor, possibly, years later.

Informal (waste) sector

Informal sector in waste management context describes an individual orgroups of waste pickers who collect recyclable wastes. The informal sector isalso involved in other waste management activities including collecting wastefrom households (door-to-door collection) and bringing it to major collection
points for a small fee; collecting organic waste for small-scale composting toearn money from the resulting compost’s sale as a soil conditioner or fertilizer.
The term informal infers unregistered, unrecognized, unprofessionalized andunmonitored by government. Therefore, it is often found that the informal
sector in waste management involves child labour, practices that endanger
personal health and safety. The informal sector in Asia plays an importantrole in waste management.

Institutions

Regularized patterns of interaction by which society organizes itself: therules, practices and conventions that structure human interaction. The
term is wide and encompassing, and could be taken to include law, social
relationships, property rights and tenurial systems, norms, beliefs, customs
and codes of conduct as well as multilateral environmental agreements,
international conventions and financing mechanisms. Institutions could
be formal (explicit, written, often having the sanction of the state) or
informal (unwritten, implied, tacit, mutually agreed and accepted). Formal
institutions include law, international environmental agreements, by laws andmemoranda of understanding. Informal institutions include unwritten
rules, codes of conduct and value systems. The term institutions should be
distinguished from organizations.

Integrated
exposure-response
function (IER)

Models that combine exposure and risk data for four sources ofcombustion-related pollution, namely outdoor air, second-hand smoke,household air pollution and active smoking.

Interlinkage

The cause-effect chain(s) that cross the boundaries of current environmental
and environment-development challenges.

Kigali Amendment

The 2016 Kigali Amendment to the Montreal Protocol on Substancesthat deplete the O3 layer aims for the phase-down of HFCs by cutting theirproduction and consumption.

Life-cycle cost

The total cost of an item throughout its lifetime, including the sum of all
recurring and non-recurring (one-time) costs over the full life span or a
specified period of goods, services, structures, or systems. It includes
the costs of planning, design, acquisition, operations, maintenance anddisposal, less any residual value and/or purchase price, installation,
operating, maintenance and upgrade costs, and remaining (residual orsalvage) value at the end of ownership or its useful life.

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Definition

Long-lived greenhouse gases(LLGHGs)

Long-lived greenhouse gases (LLGHGs), for example, CO2, CH4 and N2O,
are chemically stable and persist in the atmosphere over time scales ofa decade to centuries or longer, so that their emission has a long-term
influence on climate. Because these gases are long lived, they become
well mixed throughout the atmosphere much faster than they are removed
and their global concentrations can be accurately estimated from data
at a few locations. CO2 does not have a specific lifetime because it iscontinuously cycled between the atmosphere, oceans and land biosphereand its net removal from the atmosphere involves a range of processes
with different time scales.

Long range transport (LRT)

Atmospheric transport of air pollutants within a moving air mass for a
distance greater than 100 kilometres.

Measures contributing todevelopment priority goals

The measures that were assessed and yield the greatest benefits not only
to human health, agricultural crop yields and temperature increase but
also contribute to the achievement of the SDGs.

Meta-analysis

A statistical analysis that combines the results of multiple scientificstudies. The basic rationale behind meta-analyses is that there is acommon truth behind all conceptually similar scientific studies, but which
has been measured with a certain error within individual studies. Theiraim is to use statistical approaches to derive a pooled estimate closest
to the unknown common truth based on how this error is perceived. In
essence, all existing methods yield a weighted average from the resultsof the individual studies and what differs is the manner in which theseweights are allocated and also the manner in which the uncertainty
is computed around the point estimate thus generated. In addition toproviding an estimate of the unknown common truth, meta-analysis has
the capacity to contrast results from different studies and identify patterns
among study results, sources of disagreement among those results, orother interesting relationships that may come to light in the context ofmultiple studies.

Mitigation

Structural and non-structural measures undertaken to limit the adverse impactof natural hazards, environmental degradation and technological hazards.

Mitigation of climate change

In the context of climate change, a human intervention to reduce the sources,
or enhance the sinks of greenhouse gases. Examples include using fossil
fuels more efficiently for industrial processes or electricity generation;
switching to sources of renewable energy (solar energy and wind power);
improving the insulation of buildings and expanding forests and other sinks
to remove greater amounts of CO2 from the atmosphere.

Modelled sub-regions

The sub-regions used in this report were re-grouped for scientific convenience
when conducting the air modelling calculations based on sufficientavailable data of the sub-regions. These sub-regions have no official oradministrative significance.

TermDefinition

Montreal Protocol

The 1987 Montreal Protocol on Substances that Deplete the Ozone Layer isan international treaty designed to protect the O3 layer by phasing out the
production of numerous substances that are responsible for its depletion.
All the O3 depleting substances controlled by the Montreal Protocol containeither Cl or Br. Some O3-depleting substances (ODSs) are not yet controlled
by the Montreal Protocol, including N2O. For each group of ODSs, the treaty
provides a timetable on which the production of those substances must be
reduced and eventually eliminated.

MonsoonTraditionally defined as a seasonal reversing wind accompanied bycorresponding changes in precipitation, but it is now used to describe
seasonal changes in atmospheric circulation and precipitation associatedwith the asymmetric heating of land and sea. Usually, the term monsoon isused to refer to the rainy phase of a seasonally-changing pattern, althoughtechnically there is also a dry phase.

Morbidity

A diseased state, disability, or poor health.

Mulch Happy seeder

An alternate technology, the Happy Seeder, developed in South Asia, is a
tractor-mounted machine that cuts and lifts rice straw, sews wheat into baresoil, and deposits the straw over the sown area as mulch. It can plant thewheat seed without getting jammed by the rice straw, stop farmers fromburning residues without increasing field preparation costs or alter crop yields.
Straw mulch reduces the amount of radiation reaching and leaving the soil
surface, and therefore reduces the maximum soil temperature and increases
the minimum temperature. Straw mulch also lowers soil evaporation leading
to higher soil water content and/or crop water use.

Municipality

An administrative division composed of a defined territory and population.

Municipal waste

Residential solid waste and some non-hazardous commercial, institutional,
and industrial wastes.

Nationally determined
contributions (NDCs)

Collection of actions that countries that signed the Paris Agreement pledge toundertake to reduce national emissions and adapt to the impacts of climatechange in the post-2020 period. Actions that, by ratifying the Paris Agreement,each party to the UNFCCC binds itself to pursuing.

Negative forcing

Negative forcing (more outgoing energy) tends to cool a system.

Next-stage air quality
measures

Measures that were assessed and yield the greatest benefits to address theremaining priority emission sources reduction in Asia after implementing
Asia-wide conventional measures that proved effective in the past experienceof Asian countries.

Open biomass burning

Forest, peat land fires, agriculture residue burning and outdoor cooking.

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Term

Definition

Open dumping

The practice of placing waste in a disposal site at which solid wastes aredisposed of in a manner that does not protect the environment. The wastes
are susceptible to open burning and exposed to the elements, vectors,
and scavengers.

Open top chamber (OTC)Open top chambers are widely used to study the effects of elevated CO2
and other atmospheric gases such as O3 on vegetation. They are plastic
enclosures, with an open top, constructed of an aluminum frame coveredby panels of polyvinyl chloride plastic film. Air is pulled into the bottom of
the chamber, enriched with CO2 or O3, and then blown through the open topof the chamber. They are relatively inexpensive to construct and maintain,
however, they are not appropriate for the study of large vegetation (e.g. forest
ecosystems).

Organizations

Bodies of individuals with a specified common objective. Organizations can bepolitical (political parties, governments and ministries); economic (federationsof industry); social (non-governmental organizations and self-help groups)
or religious (church and religious trusts). The term organizations should be
distinguished from institutions.

Ozone (O3)–troposphericor ground level O3 andstratospheric O3O3 is a triatomic molecule consisting of three oxygen (O) atoms. Troposphericor ground-level O3 is an air pollutant with harmful effects on vegetation andon the respiratory systems of animals. On the other hand, O3 in the upper
atmosphere (stratospheric O3) protects living organisms by preventing
damaging ultraviolet light from reaching the Earth’s surface. This is also called
the O3 layer, where O3 concentrations are as high as 10 parts per million (ppm)
and is a vitally important region of the atmosphere. This layer of O3 is locatedapproximately 20–50 kilometers above the Earth’s surface. Stratospheric O3
is important because it prevents most of the high-energy ultraviolet solar
radiation from reaching the Earth’s surface.

Ozone depleting
substances (ODS)

Chemicals that destroy the Earth’s protective O3 layer when released into
the atmosphere. They include chlorofluorocarbons (CFCs), halon, carbon
tetrachloride (CCl4), methyl chloroform (CH3CCl3), hydrobromofluorocarbons(HBFCs), hydrochlorofluorocarbons (HCFCs), methyl bromide (CH3Br)
and bromochloromethane (CH2BrCl)

Ozone layer

The stratosphere contains a layer in which the concentration of O3 is greatest,
the so-called ozone layer. The layer extends from about 12 to 40 kilometers
above the Earth’s surface. The O3 concentration reaches a maximum between
about 20 and 25 kilometers. This layer is being depleted by human emissionsof chlorine and bromine compounds. Every year, during the southernhemisphere spring, a very strong depletion of the O3 layer takes place over the
Antarctic region, caused by anthropogenic chlorine and bromine compounds
in combination with the specific meteorological conditions in of that region.

Ozone-induced crop loss

Crop yields are decreased by ground-level O3 pollution, to differing extents
depending on genotype and environmental conditions, and this loss isTermDefinition
predicted to escalate given climate change and increasing ozone precursor
emissions in many areas. Ozone causes visible injury symptoms to foliage;
induces early senescence and abscission of leaves; reduces stomatal apertureand thereby C uptake, and/or directly reduces photosynthetic C fixation;
moderates biomass growth through C availability or more directly; decreases
translocation of fixed C to edible plant parts (grains, fruits, pods, roots) due
either to reduced availability at source, redirection to synthesis of chemical
protectants, or reduced transport capabilities through phloem; decreased C
transport to roots reduces nutrient and water uptake and affects anchorage.
Ozone can moderate or bring forward flowering and induce pollen sterility. It
induces ovule and/or grain abortion and finally reduces the ability of somegenotypes to withstand other stresses such as drought, high vapour pressure
deficit, and high photon flux density through effects on stomatal control.

Ozone precursor

Chemical compounds, such as CO, CH4, NMVOCs and NOx, which in thepresence of solar radiation react with other chemical compounds to form
O3, mainly in the troposphere.

Paris Agreement

An agreement within the United Nations Framework Convention on
Climate Change (UNFCCC), dealing with greenhouse-gas-emissions
mitigation, adaptation, and finance, starting in the year 2020. The
agreement’s language was negotiated by representatives of 196 stateparties at the 21st Conference of the Parties of the UNFCCC and adopted
by consensus on 12 December 2015. The agreement sets out a global
action plan to put the world on track to avoid dangerous climate change
by limiting global warming to well below 2°C.

Particulate matter (PM)Very small pieces of solid or liquid matter such as particles of soot, dust,
fumes, mists or aerosols. The physical characteristics of particles, and how
they combine with other particles, are part of the feedback mechanisms of
the atmosphere.The sum of all solid and liquid particles suspended in air, manyof which are hazardous.

Pathway

A pollutant pathway is the route along which a particular pollutant is distributed,
for example within a building or through an environmental system.
An exposure pathway is a channel followed by pollutants from their source
through air, soil, water, and food, to humans, animals, or their environment.

PolicyAny form of intervention or societal response. This includes not only statements
of intent, such as a water policy or forest policy, but also other forms ofintervention, such as the use of economic instruments, market creation,
subsidies, institutional reform, legal reform decentralization and institutional
development. Policy can be seen as a tool for the exercise of governance. Whensuch an intervention is enforced by the government, it is called public policy.

Policy intervention

A general inserted political and governmental process of carrying out
programmes in order to fulfill specified policy objectives; a responsibility chiefly
of administrative agencies.

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Term

Definition

Pellet stove

A stove that burns compressed wood or biomass pellets to create a sourceof heat for residential and sometimes industrial spaces.

Photochemical reaction

Refers to any chemical reaction which occurs as a result of light energy fromthe sun.

Phytotoxicity

A term used to describe the degree of toxic effect by a compound on plant
growth.

Pollutant

Any substance that causes harm to the environment when it mixes with soil,
water or air

Pollutant standard index(PSI) (air quality index)

A number used to indicate the level of pollutants in air derived by averaging
data collected for the past 24 hours. The PSI has been used in a number ofcountries. Its calculation may differ from country to country and thus different
names names are used by countries for their indices such as Air Quality HealthIndex, Air Pollution Index and Pollutant Standards Index. The PSI is usuallyreported as a number on a scale of 0 to 500. The index figures enable thepublic to determine whether the air pollution levels in a particular location are
good, moderate, unhealthy or hazardous.

Pollution

The presence of minerals, chemicals or physical properties (e.g. sound) at
levels that exceed the values deemed to define a boundary between “goodor acceptable” and “poor or unacceptable” quality, which is a function of thespecific pollutant.

Post-combustion controls

The systems that clean up exhaust gas left by burning fuel.

Poverty

The pronounced deprivation of well-being.

Precipitation

Any and all forms of water, whether liquid or solid, that fall from the atmosphereand reach the Earth’s surface.

Precursor (pollutants oremission)

A compound that participates in a chemical reaction that produces anothercompound. Atmospheric compounds that are not greenhouse gases oraerosols, but that have an effect on greenhouse gas or aerosol concentrations
by taking part in physical or chemical processes regulating their production
or destruction rates.

Pre-industrial

Prior to widespread industrialization and the resultant changes in theenvironment. Typically taken as the period before 1750.

Premature mortality or
premature death

Death that occurs before the average age of death in a certain population.
The World Health Organization (WHO) defines a premature death as a deaththat occurs before the age of 50. (World Health Report 1998). The WHO
indicates that the age of 50 reflected the global average life expectancy in1948. (World Health Report 1998) This definition exemplifies the arbitrarinessof some of the definitions of premature death. To measure the burden of
disease in a society, epidemiologists calculate how many years of life wereTermDefinition
lost to premature death. This is calculated by subtracting the various ages atwhich individuals in a population died from the average life expectancy or an
arbitrarily chosen number such as the age of 65. This measure is called years ofpotential life lost (YPLL).

Primary energy

Energy embodied in natural resources (such as coal, crude oil, sunlight or uranium)that has not undergone any anthropogenic conversion or transformation.

Primary productivity

The transformation of chemical or solar energy to biomass. Most primary
production occurs through photosynthesis, through which green plants
convert solar energy, CO2, and water to glucose and eventually to plant tissue.
In addition, some bacteria in the deep sea can convert chemical energy tobiomass through chemosynthesis.

Primary wastewater
treatment

In the primary stage of wastewater treatment, sewage flows through largetanks which are used to settle sludge while grease and oils rise to the surface
and are skimmed off. Tanks are usually equipped with mechanically driven
scrapers that continually drive the collected sludge towards a hopper in thebase of the tank where it is pumped to sludge treatment facilities.

Projection

The act of attempting to produce a description of the future subject toassumptions about certain preconditions, or the description itself, such as“assuming it is 30ºC tomorrow, we will go to the beach”.

Purchasing power parity(PPP)

The number of currency units required to purchase the amount of goods andservices equivalent to what can be bought with one unit of the currency of thebase country, for example, the US dollar.

Radiative (or climate)forcing (RF)Radiative forcing is the change in the net vertical irradiance, expressed in watts
per square metre (W/m2), at the tropopause due to an internal change or achange in the external forcing of the climate system, such as, for example, achange in the concentration of CO2 or the output of the sun. The measurementof the capacity of a gas or other forcing agents to affect that energy balance,
thereby contributing to climate change. Radiative forcing expresses thechange in energy in the atmosphere due to greenhouse gas emissions. The
RF of a gas is defined as the difference between incoming solar radiation andoutgoing infrared radiation caused by the increased concentration of that gas.
A positive radiative forcing tends to warm the surface and a negative radiative
forcing tends to cool the surface. The radiative forcing is normally quoted asa global and annual mean value.

Reference scenario

See Baseline scenario.

Renewable energy

Energy that is collected from renewable resources which does not rely on
finite stocks of fuels and are naturally replenished on a human timescale,such as sunlight, wind, rain, tides, waves and geothermal heat. Renewableenergy often provides energy in four important areas: electricity
generation, air and water heating/cooling, transportation and rural(off-grid) energy services.

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Term

Definition

Residence time

Residence time (also known as removal time) is the average amount of timethat a particle spends in a particular system.

Sanitary or engineered
landfill

A sanitary landfill is a land disposal site for waste, which is designed to protectfrom environmental pollution and health risks. It is the opposite of an open
dump. Landfills are built to concentrate the waste in compacted layers to
reduce the volume and monitored for the control of liquid and gaseous effluent
in order to protect the environment and human health. It is an engineered
pit, in which layers of solid waste are filled, compacted and covered for final
disposal. It is lined at the bottom to prevent groundwater pollution. Engineered
landfills consist of a lined bottom; a leachate collection and treatment system;
groundwater monitoring; gas extraction (the gas is flared or used for energy
production); and a cap system. The capacity is planned and the site is chosen
based on an environmental risk assessment study (UNEP 2002). Landfills
need expert design as well as skilled operators and proper management
to guarantee their functionality.

Scenario

A description of how the future may unfold based on “if-then” propositions,typically consisting of a representation of an initial baseline situation, adescription of the key drivers and changes that lead to a particular futurestate. For example, “given that we are on holiday at the coast, if it is 30ºC
tomorrow, we will go to the beach”.

Secondary pollutants/
particles

Pollutants that are not directly emitted as such, but form when otherpollutants (primary pollutants) react in the atmosphere. Particles thatare formed in the atmosphere. Secondary particles are products ofthe chemical reactions between gases, such as NOx, sulphur oxides, ammonia,
and organic products.

Secondary wastewater
treatment
Security

Secondary wastewater treatment is a biological treatment process to remove
biodegradable dissolved and colloidal organic matter using aerobic biologicaltreatment processes. Secondary treatment follows primary treatment.
Relates to personal and environmental security. It includes access to naturaland other resources and freedom from violence, crime and war, as well as
security from natural and human-caused disasters.

Shale gas

Shale gas refers to natural gas that is trapped within shale formations. Shales
are fine-grained sedimentary rocks that can be rich sources of petroleum andnatural gas.

Short lived climate
pollutants (SLCPs)

Short-lived climate pollutants are defined as gases and particles that contributeto warming and that have a lifetime from a few days to approximately 10 years.
These include black carbon (BC), tropospheric ozone (O3) and its precursors
CO, NMVOC and NOx, CH4, and some HFCs. Short-lived climate pollutants
are powerful climate forcers that remain in the atmosphere for a much
shorter period of time than CO2, yet their potential to warm the atmospherecan be many times greater. Certain short-lived climate pollutants are also
dangerous air pollutants that have harmful effects for people, ecosystems andagricultural productivity.

Term

Definition

Sociodemographic index

A summary measure of a geography’s socio-demographic development.
The index i is based on average income per person, educational attainment
and total fertility rate (TFR). A sociodemographic index (SDI) contains aninterpretable scale: zero represents the lowest income per person, lowest
educational attainment and highest TFR observed across all GBD geographies.
The estimates were developed by GBD researchers.

Solid fuel

Refers to various types of solid material that are used as fuel to produce energy
and provide heating. Solid fuels include wood, charcoal, peat, coal, hexamine
fuel tablets, and pellets made from wood, corn, wheat, rye and other grains.

Source apportionment

A practice of deriving information about pollution sources and the amountthey contribute to ambient air pollution levels. This task can be accomplishedusing three main approaches: emission inventories, source-oriented models
and receptor oriented models.

Species (chemical)

A set of chemically identical atomic or molecular structural units in a solid array.
Species can be the molecular fragments, ions, atoms and molecules thatcan explore the same set of molecular energy levels on a defined time scaleor being subjected to a chemical process or to a measurement.

Stomata

Pores found in the leaf and stem of the plant epidermis that are used for gas
exchange.

Stomatal conductance

A numerical measure of the rate of passage of either water vapour or carbon
dioxide through the stomata of a plant.

Stratospheric ozone

Region of the atmosphere between the troposphere and mesosphere, having alower boundary of approximately 9 kilometres at the poles to 16 kilometres atthe equator and an upper boundary of approximately 50 kilometres. Depending
upon latitude and season, the temperature in the lower stratosphere canincrease, be isothermal, or even decrease with altitude, but the temperaturein the upper stratosphere generally increases with height due to absorptionof solar radiation by O3.

Sulphate aerosols

Particulate matter that consists of compounds of sulphur (S) formed by theinteraction of SO2 and sulphur trioxide (SO3) with other compounds in theatmosphere. Sulphate aerosols are injected into the atmosphere from the
combustion of fossil fuel and the eruption of volcanoes like Mt. Pinatubo.
Recent theory suggests that sulphate aerosols may lower the Earth’s
temperature by reflecting away solar radiation (negative radiative forcing).

Sustainability

A characteristic or state whereby the needs of the present and local
population can be met without compromising the ability of future
generations or populations in other locations to meet their needs.

Sustainable development

Development that meets the needs of the present generation withoutcompromising the ability of future generations to meet their own needs.

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Term

Definition

Sustainable Development
Goals

The Sustainable Development Goals (SDGs) are an intergovernmental set ofdevelopment goals. All United Nations members have committed to work
towards the achievement of all the goals by their target date 2030. The SDGs
are made up of 17 goals and 169 indicators. The SDGs have replaced theMillennium Development Goals.

Synergies

These arise when two or more processes interact in such a way that theoutcome is greater than the sum of their separate effects (e.g. multiplicative
rather than additive).

Technology

Physical artefacts or the bodies of knowledge of which they are an expression.
Examples are renewable-energy technologies and waste-to-energy
technology. Technology and institutions are related. Any technology has a
set of practices, rules and regulations surrounding its use, access, distribution
and management.

Terrestrial ecosystems

A terrestrial ecosystem is a type of ecosystem found only on land masses.
Six primary terrestrial ecosystems exist: tundra, taiga, temperate deciduous
forest, tropical rain forest, grassland and desert. The biotic or living things
found in an ecosystem, include various life forms, such as plants and animals.
The abiotic or non-living things found in an ecosystem, include the various
land forms and the climate.

Tertiary wastewater
treatment

The purpose of tertiary wastewater treatment is to provide a final treatment
stage to raise the effluent quality before it is discharged to the receiving
environment (sea, river, lake, ground, etc.).

Time-series study/analysis(short term)

Time-series studies are routinely used to estimate associations between
adverse health outcomes and short-term exposures to ambient air pollutants.
The Poisson log-linear model with the assumption of constant over-dispersion
is the most common approach, particularly when estimating associations
between daily air pollution concentrations and aggregated counts of adverse
health events throughout a geographical region.

Third pole area

The Third Pole contains the world’s highest mountains, including all 14 peaks
above 8,000 metres, is the source of 10 major rivers, and forms a formidable
global ecological buffer. It covers the Hindu Kush-Himalayan region with anarea of more than 4.3 million square kilometres in Afghanistan, Bangladesh,
Bhutan, China, India, Myanmar, Nepal, and Pakistan. This region stores moresnow and ice than anywhere else in the world outside the polar regions, giving
its name: the Third Pole.

Transboundary pollution

The pollution that originates in one country but, by crossing the border throughpathways of water or air, is able to cause damage to the environment inanother country.

Troposphere

The lowest part of the atmosphere from the Earth’s surface to about
10 kilometres in altitude in midlatitudes (ranging from 9 kilometres to
16 kilometres in high latitudes in the tropics on average) where clouds

TermDefinition
and weather phenomena occur. In the troposphere temperatures generally
decrease with height.

Urbanization

An increase in the proportion of the population living in urban areas.

Volatile organic
compounds (VOCs)

Organic chemical compounds that under normal conditions are gaseousor can vaporize and enter the atmosphere. VOCs include such compounds
as CH4, benzene, xylene, propane and butane. CH4 is primarily emitted
from agriculture (from ruminants and cultivation), whereas non-CH4 VOCs(or NMVOCs) are mainly emitted from transportation, industrial processes
and use of organic solvents. Organic chemical compounds that have highenough vapour pressures under normal conditions to significantly vaporize
and enter the atmosphere include hydrocarbons (CxHy ) but also otherorganic chemicals that can be emitted from a very wide range of sources,
including fossil fuel combustion, industrial activities, and natural emissions
from vegetation and fires. Some anthropogenic VOCs such as benzene
are known carcinogens. VOCs are also of interest as chemical precursorsof ground-level O3 and aerosols. The importance of VOCs as precursors
depends on their chemical structure and atmospheric lifetime, which canvary considerably from compound to compound. Large VOCs oxidize in theatmosphere to produce nonvolatile chemicals that condense to form aerosols.
Short-lived VOCs interact with NOx to produce high ground-level O3 in polluted
environments. CH4, the simplest and most long-lived VOC, is of importanceboth as a greenhouse gas and as a source of background tropospheric ozone.

Vulnerable people

The groups and communities at a higher risk for poor health as a result of
the barriers they experience to social, economic, political and environmental
resources, as well as limitations due to illness or disability.

Waste heat recovery

The process of harnessing the heat generated by power plants or industrial
machinery, which would otherwise remain unused, in order to alleviate
demands on energy generation. This reduces the total amount of fuel needed.

Wastewater treatment

Any of the mechanical, biological or chemical processes used to modify thequality of wastewater in order to reduce pollution levels.

World Health Organization(WHO) air quality guideline

A document developed by the WHO containing recommendations forclinical practice or public health policy. WHO air quality guidelines, which aredesigned to offer guidance in reducing the health impacts of air pollution,
are based on expert evaluation of current scientific evidence.

World Health Organization(WHO) Interim Target

A level of pollution higher than that set by the WHO air quality guideline,
established as an interim target to assist implementing agencies to makeprogress towards meeting the guideline levels. The interim targets are given
for each air pollutant. These targets aim to promote a shift from high air
pollutant concentrations, which have acute and serious health consequences,
to lower ones. If these targets were to be achieved, one could expect significant
reductions in risks for acute and chronic health effects from air pollution.

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The series of Air Pollution in Asia and the Pacific: Science-based Solutions includes:

Summary

Main Report

25 Clean air
measures booklet