Chapter

Air Quality measures exposure to fine particulate matter, nitrogen dioxide, and percentage of the population burning solid fuel indoors.

Overview

 

What it measures:

This category includes four key indicators: Air Pollution- Average Exposure to PM2.5 (fine particulate matter in micrograms per cubic meter (µg/m3); Health Risk Exposure to PM2.5; PM2.5 Exceedance (an average of the percentage of the population exposed to PM2.5 levels at 10 µg/m3, 15 µg/m3, 25 µg/m3, and 35 µg/m3 - World Health Organization’s (WHO) air quality guidelines and interim I, II, and III targets;[footnote 1] Household Air Quality – Indoor Solid Fuel Usage; and Average Concentration of NO2 (in parts per billion). 

Why we include it:

Suspended particulates contribute to acute lower respiratory infections and other diseases such as cancer. They can penetrate human lung and blood tissue, leading to higher incidences of cardiovascular and lung disease. Fine particulates or PM2.5 (2.5 microns and smaller) lodge deep in lung tissue and are injurious to health.

Cooking with solid fuels over open fires or in simple stoves exposes households to daily pollutant concentrations that lie between those of second-hand smoke exposure and active smoking. A measure of solid fuel use is a proxy for household air pollution and serves as an estimation of health impacts from household air pollution in the 2013 GBD.[footnote 2]

Nitrogen dioxide (NO2) is produced as a result of road traffic and other fossil fuel combustion processes. Strong associations between NO2 and mortality have been identified in multi-city studies around the world.[footnote 3] Health risks of NO2 come from itself or its reaction products including Ozone (O3) and secondary particles.[footnote 4] According to the United States Environmental Protection Agency, direct exposure to NO2, ranging from 30 minutes to 24 hours, can cause airway inflammation and diminished respiratory function for people with asthma.[footnote 5] NO2, when combined with volatile organic compounds (VOCs), forms ground-level ozone or smog observable in many cities. Inhalation of ozone leads to increased incidence of acute respiratory illness in susceptible populations including children, the elderly, and people with lung diseases. Small particles are formed when NO2 reacts with ammonia, moisture, and other compounds. If inhaled, these particles can penetrate deeply into the lungs, causing respiratory disease and aggravating existing heart disease.[footnote 5]

Where the data come from:

The satellite-derived PM2.5 data were provided by Aaron van Donkelaar of Dalhousie University. Population data for average exposure PM2.5 concentrations and measurement of the proportion of the population above various PM2.5 concentration thresholds were obtained from the Global Rural Urban Mapping Project, v.1 at the NASA Socioeconomic Data and Applications Center hosted by the Center for International Earth Science Information Network (CIESIN) at Columbia University.

The Household Air Quality data came from the WHO Global Health Observatory Data Repository[footnote 6] and MDG indicators,[footnote 7] which provide estimates of the percentage of households using solid fuels (coal, wood, charcoal, dung, and crop residues), liquid fuels (kerosene), gaseous fuels (LPG, natural gas, biogas) and electricity. WHO and MDG data come from household surveys and national censuses. Data for population-weighted annual mean NO2 were provided by Jeffrey A. Geddes of Dalhousie University, who derived these data from the Tropospheric Emissions Monitoring Internet Service.[footnote 8] For more information, see 2016 EPI Metadata.

The Environmental Risk Exposure data for air quality came from the Institute for Health Metrics and Evaluation’s Global Burden of Disease (GBD) study,[footnote 9] the world’s most comprehensive comparative risk assessment of epidemiological trends (see Health Impacts Issue Profile).

What are the targets:

10 µg/m3 for Average Exposure to PM2.5 (fine particulate matter); 0 for Health Risk Exposure to PM2.5; 0% for PM2.5 Average Exceedance; 0% for Household Air Quality – Indoor Solid Fuel Usage; 0 parts per billion for Average Concentration of NO2.

 

Description

Particles smaller than 2.5 microns in diameter, known in shorthand as PM2.5, are fine enough to lodge deep into human lung and blood tissue. They place exposed populations at risk of heart and lung diseases, ranging from stroke to lung cancer. In severe cases, this pollution contributes directly to fatalities.[footnote 10] Airborne particulates originate from a variety of sources. PM2.5 is generally the product of combustion, whether anthropogenic, like car emissions and coal burning, or through forest fires and volcanoes. For vulnerable populations, including youth and elderly, high concentrations of PM2.5 can be a particularly virulent killer. The leading cause of child mortality ages one to five worldwide is pneumonia, and fine particulates are a major global contributor to its incidence.[footnote 11]

Despite its known health impacts, many countries do not monitor PM2.5, usually because of lack of capacity, resources, technology, or public demand. Monitoring gaps primarily occur in developing countries outside of North America and Western Europe, where air pollution is more severe.[footnote 12] EPI collaborated with Dalhousie University researchers who use satellite data to assess global, national exposure to PM2.5. Unlike ground-based monitors, which are primarily concentrated in urban areas and can be sporadically stationed, satellite data provide consistent and complete values using the same methods and technology for every country (see Figure 11).

With this satellite data, the 2016 EPI will include the only national indicator of population exposure to PM2.5 on a global scale. More than half of the population in 58 countries lives in regions with annual mean PM2.5 concentrations in excess of the WHO guideline of a 10 μg/m3. Large, urbanizing centers with heavy industrial activity and high concentrations of vehicles suffer from heavy contamination.[footnote 13] In Beijing, for instance, air quality hit red alert levels for the second time ever in December 2015 causing schools to shut down and limits imposed on vehicle use and outdoor activities.[footnote 14]

Air Quality: A Global Challenge

Developed countries are not immune from pollution. In Paris, headlines proclaimed that the City of Light had become the City of Haze, with air pollution ratings worse than Beijing and Delhi.[footnote 15] Experts blamed government incentives to use diesel vehicles by subsidizing the cost of diesel fuel by 15 percent. Diesel, which is more popular in Europe, is more fuel efficient, but comes with a cost of nitrogen dioxide oxide emissions that generate ozone pollution and other public health concerns. The severity of pollution in Paris was underscored later in the year when the world’s largest carmaker Volkswagen was exposed using specialized software to cover up the true NO2 emissions from their vehicles.[footnote 16] In London, new research linking NO2 pollution to 9,500 deaths annually from long term exposure put air pollution concerns back on the map.[footnote 17] Similar studies of death and illness related to air pollution have been translated into monetary values to spur policy action.              

While air pollution in developed countries is primarily the product of industrialization and urbanization, air pollution in many developing countries commonly has a different source: biomass burning. The combustion of organic refuse, charcoal, wood, animal dung, and agricultural waste, such as straw, nut shells, and rice husks, is prevalent in rural and urban areas of the developing world, and the consequences mat be felt far from the burn sites. For example, massive forest and peat fires in Indonesia have lead to severe cross-boundary air pollution impacting Singapore (see Box 6: Indonesia on Fire, Cross-Boundary Public Health Hazards). 

Box 6: Indonesia on Fire, Cross-Boundary Public Health Hazards

Prescribed fires in Indonesia’s Kalimantan and Sumatra regions burned 21,000 km2 of forest and peatland in 2015. It released more CO2 emissions in a few weeks than Germany does in a year and sent noxious air pollution into cities and nations throughout the region. What policies can help control this trans-boundary pollution?

Fires in Indonesia, which burned more than 2.1 million hectares of forest and peatlands in 2015,[footnote 18] have raged in dry seasons year on year, killing people and wildlife, destroying livelihoods, and producing a thick haze that drifts north from Sumatra and west from Borneo, blanketing Singapore and Malaysia in smoke.[footnote 19] The choking haze, which covered a vast expanse of Southeast Asia, killed more than 20 people and sickened at least half a million, offering a stark reminder that pollution and its pernicious effects do not respect national boundaries.[footnote 18] It will require local policy and enforcement in Indonesia along with regional cooperation to remedy this environmental and human health disaster.

The more than 94,000 individual Indonesian fires are primarily the result of “slash and burn” land clearing,[footnote 20] a practice in which landowners, both large and small, raze forested areas and burn the debris or drain peat bogs and incinerate carbon-rich peat deposits. The fires clear and prepare land for planting crops or sometimes to interfere with their competitors’ operations. Indonesia is the world’s largest producer of palm oil, and farmers light fires to make way for more palm plantations, pulpwood, and other agricultural operations.[footnote 20] Most of the fires raged outside of official agricultural and pulpwood concessions, meaning they were set illegally, and many of these fires reduced protected forest and peatlands to charred fields.[footnote 21] Shifting weather patterns have contributed to the disaster, as an extended dry season has allowed the fires to burn longer and over a larger area than ever before.[footnote 20]

The impacts from these fires are widespread, both geographically and in the types of damages they cause. Trans-boundary air pollution has in some places exceeded 2,000 on the Pollutant Standard Index. Anything above 300 is hazardous to human health.[footnote 20] This air pollution causes widespread respiratory infections and premature deaths.[footnote 22] The fires have released more than 1.5 billion metric tons of carbon dioxide this year alone, tripling Indonesia’s greenhouse gas emissions and making it the fourth largest emitter of climate pollutants.[footnote 22] The fires have also devastated wildlife, threatening one of the most biodiverse ecosystems on Earth. Endangered species, including Orangutans, have lost critical habitat. Many animals have been sickened by the smoke, and the flames have killed untold numbers.[Footnote 23] In addition to environmental costs, estimates of the economic impacts exceed $14 billion USD.[footnote 24]

A transboundary disaster of this magnitude requires responses at all level of government. In 2014, Singapore passed the Transboundary Haze Pollution Act, giving its government the authority to prosecute companies operating in Indonesia that cause air pollution in Singapore.[footnote 21] Also in 2014, Indonesia ratified the Association of Southeast Asian Nations (ASEAN) Agreement on Transboundary Haze Pollution, which, among other policies, improves fire monitoring.[footnote 21]

Laws are only a starting point for improving environmental performance. In 2015, faceless corporations and anonymous people have burned more land and created more transboundary pollution than in years past, despite new laws forbidding these practices. In order to manage land for the benefit of people and the environment, nations have to take responsibility for enforcing existing laws and welcome international monitoring assistance. National sovereignty must be respected, and yet Indonesia’s fires and haze violate the sovereignty of neighboring states. Pollution does not respect political boundaries. The parties responsible for pollution, however, are subject to governmental authority. Only through cooperation and respect for the rule of law can governments make lasting environmental progress.

Household Air Pollution

Cooking with solid fuels over open fires or in simple stoves exposes households to dangerous pollutant concentrations. Solid fuel combustion is associated with increased mortality from pneumonia and other acute lower respiratory diseases among children. Among adults it is connected to increased mortality from chronic obstructive pulmonary disease and, where coal is used, lung cancer.[footnote 1] In fact, chronic exposure to air pollution produced by the combustion of cooking fuels is among the world’s most significant and most silent killers. The most recent Global Burden of Disease (GBD) project found household air pollution from solid fuel responsible for approximately 2.8 million premature deaths worldwide.[footnote 25]

The burning of solid fuels is far more prevalent in developing countries and in rural areas where the population lacks access to modern cooking technology. Biomass and coal are often burned in simple stoves or open fires in poorly ventilated cooking spaces. Nearly 730 million people in Sub-Saharan Africa rely on the traditional use of solid biomass for cooking.[footnote 26] And its effects are not isolated to kitchens. Data show that smoke may pervade the rest of the house and the outdoors. Families that cook outdoors also experience adverse health effects, though at a lower rate. Households using clean fuel sources amidst a community of solid fuel users may still be exposed to harmful smoke by their neighbors.

The 2016 EPI indicator for Household Air Pollution reveals a clear correlation between national income and household air pollution. The numbers of people significantly affected by solid fuel contamination, low-income households from developing countries, is likely even greater than the data indicate, as families in developing countries tend to be larger. According to the Global Alliance for Clean Cookstoves, a public-private partnership hosted by the United Nations Foundation, three billion people cook over open flames or use basic stoves with traditional biomass fuels.[footnote 27]

Solutions to address household air pollution focus on reducing emissions through the use of cleaner fuels, such as liquid petroleum gas and electricity. Installing chimneys or smoke hoods on simple stoves might seem a quick fix, but the scarcity of wood and potential risks to the environment posed by collecting biomass are another compelling argument against in-home biomass use. The Global Alliance for Cookstoves is working to replace traditional stoves with clean cookstoves that are more efficient and reduce household air pollution. Largely prompted by environmental concerns, China in the early 1980s undertook a large-scale attempt at improving rural household stoves. Since then the country has installed nearly 200 million improved stoves, reducing household air pollution and easing the environmental burden of biomass demand.[footnote 28] The Global Alliance for Clean Cookstoves tries to foster public and private cooperation to make clean cookstoves and non-biomass fuels widely available in the greater developing world.

While the Household Air Pollution indicator is acutely relevant for many developing countries where majorities rely on indoor fuel combustion for cooking and heating, data to assess indoor air quality in residential and commercial buildings is lacking. This gap is particularly critical, considering more than 50 percent of the global population lives in cities, with another 2.5 billion projected to live in cities by 2050.[footnote 29] Combined with the fact that people living in cities spend the majority of time indoors, data to assess air quality in homes and offices is needed to understand health impacts from indoor sources where solid fuels aren’t burned but where VOCs and PM are still problems. In countries with high outdoor air concentrations of PM, indoor air quality is frequently no improvement over outdoor air quality. A recent report by real estate developer Jones Lang LaSalle and environmental consultancy PureLiving China evaluated 160 offices in Beijing and found 90 percent had indoor air quality conditions comparable to outdoor air pollution levels.[footnote 30]

Air in the Sustainable Development Goals (SDGs)

Ultimately, policy has an important role to play in reducing both outdoor and household air pollution.[footnote 31] Efforts to address outdoor air pollution emerged during the latter half of the 20th century. National and international laws aimed at phasing out dirty industrial fuels such as coal, regulating auto emissions, and incentivizing better energy efficiency have all proven effective at improving air quality.[footnote 32] Despite MDG efforts to encourage policy interventions to reduce household air pollution, the 2016 EPI shows that in one-third of countries had greater than 50 percent of the population continue using solid fuels indoors.

Unlike environmental health issues included in the EPI that improve with economic growth, air pollution for many countries worsens with industrialization and urbanization, making the tasks for policymakers more difficult and urgent. Air is included in the opening text of the Sustainable Development Goals (SDGs), which perceives the issue as central to both sustainable development and human health. The SDGs include targets to reduce death and illness from poor air quality under Goal 3 to ensure healthy lives and well-being. Air quality is also highlighted in Goal 11 on cities (see Box 7: Helping Indian Cities Breathe Easier) and Goal 12 on sustainable consumption and production. Improvements in technology, including low-cost air sensors, are critical in helping to fill air quality data gaps and allow for real time monitoring of health risks. This new data, along with creative visualizations, put air quality squarely into the public eye and help to spur policy discussion

Box 7: Helping Indian Cities Breathe Easier

Responding to pressure from civil society and media, India has created an Air Quality Index to measure and track air pollution in the country’s largest cities. How is this new data shaping the national debate on air quality?

In December 2015, Indian officials in Delhi launched an odd-even day driving restriction program as an emergency measure to reduce pollutant loads, marking an important step forward in combating the air pollution that has plagued the rapidly industrializing country for several decades.[footnote 33] These challenges peaked in the late 1990s, during which time millions of new cars were introduced to India’s roads. While gains have been made, the country still has a long way to go.

Indian officials initially dismissed the fact that air pollution levels in major Indian cities far exceeded thresholds deemed safe[footnote 34] by both India's National Ambient Air Quality Standards[footnote 35] and the World Health Organization's Air Quality Guidelines.[footnote 13] Last year, however, Indian pollution-control regulators changed their posture and launched the country’s own air pollution index, called the Air Quality Index (AQI), in April 2015.[footnote 36] Their Central Pollution Control Board monitors and regulates the standard spectrum of air pollutants, including tiny, dangerous particles known as PM2.5, ozone, carbon monoxide, and others. Indian regulators utilize data on these pollutants to assign AQI values to individual cities, using a relative scale where a city with the worst pollutant reading is given the lowest AQI for that pollutant.

India’s air pollution index has received extensive media attention and mixed reviews since its debut. Despite its expansion to more than 60 cities, the AQI’s exact data collection method remains unclear.[footnote 37] Additionally, while environmental organizations welcomed the move, many expressed concerns over the absence of a public health advisory system for cities receiving poor AQI scores.[footnote 38]

Monitoring and ranking air pollution levels is an important advance in a country where rigorous government measures on air pollution reduction are long overdue. High rates of acute respiratory infection are widespread and increasing, with reported cases rising 30 percent over 2010 levels. One study estimates that half of Delhi’s schoolchildren will never recover full lung capacity.[footnote 39] Indian leadership did not announce any major changes to the country’s air pollution control efforts with the AQI, but since the launch, the government has begun to address the air pollution dilemma.[footnote 37] A collaborative state and federal air pollution control plan was released in December 2015, filling a critical regulatory gap made obvious by air quality reports from the AQI. In addition to the odd-even vehicle driving restrictions implemented that month, a large coal-fired power plant in Delhi was shut down.[footnote 33] Beginning in 2017, vehicles will be required to comply with new emission standards to curb nitrogen dioxide and particulate matter emissions from diesel engines.[footnote 40]

The transition to a more breathable India is facing predictable policy barriers. A recent ban on diesel cars older than ten years in Delhi is on the verge of collapse due to congested traffic checkpoints and enforcement snags faced by city officials.[footnote 33] These and other new policies are also hampered by an insufficient capacity of Delhi’s police to regulate on-road vehicles and a public transportation system that strains to meet increasing traffic demands. But with its new air quality index continuously informing the policy process, India is showing the will to strengthen and support new controls on the deadly air pollution that once was taken for granted as the cost of modernizing.

Infographic: Outdoor

Infographic

Show footnotes

  1. World Health Organization. (2014). Ambient (outdoor) air quality and health. Available:   http://www.who.int/mediacentre/factsheets/fs313/en/. ↩

  2. United Nations. (n.d.). Millennium Development Goals Indicators. Available: http://mdgs.un.org/unsd/mdg/Metadata.aspx?IndicatorId=29. ↩

  3. Geddes J. A., Martin R. V., Boys B. L., & van Donkelaar A. (2015). Long-Term Trends Worldwide in Ambient NO2 Concentrations Inferred from Satellite Observations. Environmental Health Perspectives. http://dx.doi.org/10.1289/ehp.1409567. ↩

  4. World Health Organization. (2003). Health aspects of air pollution with particulate matter, ozone and nitrogen dioxide: report on a WHO working group, Bonn, Germany 13-15 January 2003. Available: http://www.euro.who.int/__data/assets/pdf_file/0005/112199/E79097.pdf. ↩

  5. United States Environmental Protection Agency. (2015). Health. Available: http://www3.epa.gov/airquality/nitrogenoxides/health.html. ↩

  6. World Health Organization. (n.d.). Population using solid fuels (%) (Public health and environment). Available: http://apps.who.int/gho/data/node.imr.WHS5_512?lang=en. ↩

  7. United Nations. (n.d.). Millennium Development Goals Indicators, Available: http://mdgs.un.org/unsd/mdg/SeriesDetail.aspx?srid=712&crid. ↩

  8. Tropospheric Emissions Monitoring Internet Service. (n.d.). Available: http://www.temis.nl/index.php. ↩

  9. Institute for Health Metrics and Evaluation. (n.d.). Global Burden of Disease. Available: http://www.healthdata.org/gbd. ↩

  10. Goldberg, M. (2008). A systematic review of the relation between long-term exposure to ambient air pollution and chronic diseases. Reviews on Environmental Health, 23, 4, 243-298. ↩

  11. World Health Organization. (2014). Children: reducing mortality. Available:  http://www.who.int/mediacentre/factsheets/fs178/en/. ↩

  12. Engel-Cox, J., Kim Oanh, N. T., van Donkelaar, A., Martin, R. V., & Zell, E. (2013). Toward the next generation of air quality monitoring: Particulate Matter. Atmospheric Environment, 80, 584-590. ↩

  13. World Health Organization. (2005). WHO Air quality guidelines for particulate matter, ozone, nitrogen dioxide and sulfur dioxide, Global update 2005, Summary of risk assessment. Available:  http://apps.who.int/iris/bitstream/10665/69477/1/WHO_SDE_PHE_OEH_06.02_e.... ↩

  14. Reuters. (2015, December 18). Beijing grinds to a halt as second ever ‘red alert’ issued over severe smog. The Guardian. Available: http://www.theguardian.com/world/2015/dec/18/beijing-pollution-second-ev.... ↩

  15. Willsher, K. (2015, March 23). Paris chokes on pollution: City of Light becomes City of Haze. Los Angeles Times. Available: http://www.latimes.com/world/europe/la-fg-france-paris-smog-20150323-sto.... ↩

  16. The Economist. (2015, September 26). The Volkswagen Scandal. A mucky business. Available: http://www.economist.com/news/briefing/21667918-systematic-fraud-worlds-.... ↩

  17. Vaughan, A. (2015, July 15). Nearly 9,500 people die each year in London because of air pollution - study. The Guardian. Available: http://www.theguardian.com/environment/2015/jul/15/nearly-9500-people-di.... ↩

  18. Jatmiko, A. & N. Karmini. (2015, November 16). Indonesia's vast forest fires create ecological disaster, health problems, economic losses. Star Tribune. Available: http://www.startribune.com/vast-forest-fires-in-indonesia-spawn-ecologic.... ↩

  19. Minnemeyer, S. (2015, September 24). Indonesian Fires Create “Hazardous” Levels of Air Pollution in Singapore. World Resources Institute. Available: http://www.wri.org/blog/2015/09/indonesian-fires-create-%E2%80%9Chazardo.... ↩

  20. Lamb, K. (2015, October 26). Indonesia's fires labelled a 'crime against humanity' as 500,000 suffer. The Guardian. Available: http://www.theguardian.com/world/2015/oct/26/indonesias-fires-crime-agai.... ↩

  21. Freedman, A. (2015, October 16). Indonesia’s peat fires have released more greenhouse gases than Germany does in an entire year. Mashable. Available: http://mashable.com/2015/10/16/indonesia-peat-fires-carbon-bomb/#c7RF0cd.... ↩

  22. Bolch, O. (2015, November 11). Indonesian forest fires: all you need to know. The Guardian. Available: http://www.theguardian.com/sustainable-business/2015/nov/11/indonesia-fo.... ↩

  23. Cochrane, J. (2015, October 31). Indonesia’s Forest Fires Take Toll on Wildlife, Big and Small. The New York Times. Available: http://www.nytimes.com/2015/10/31/world/asia/indonesia-forest-fires-wild.... ↩

  24. Otto, B. (2015, October 9). Smoky Haze Costing Southeast Asia Billions of Dollars. The Wall Street Journal. Available: http://www.wsj.com/articles/smoky-haze-envelops-southeast-asia-1444389741?alg=y. ↩

  25. Lim S., et al. (2015). Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks in 188 countries, 1990–2013: a systematic analysis for the Global Burden of Disease Study 2013. The Lancet. Available:  http://www.sciencedirect.com/science/article/pii/S0140673615001282. ↩

  26. International Energy Agency. (2014). World Energy Outlook 2014 Factsheet: Energy in sub-Saharan Africa today. Available: https://www.iea.org/media/news/2014/press/141013_WEO_Africa_Energy_OutlookFactsheet1.pdf. ↩

  27. Global Alliance for Clean Cookstoves. (n.d.). Available: http://cleancookstoves.org/home/index.html. ↩

  28. Sinton, J. E., Smith, K. R., Peabody, J. W., … (2004). An assessment of programs to promote improved household stoves in China. Energy for Sustainable Development, 8, 33-52. ↩

  29. United Nations Department of Economic and Social Affairs. (2014). World Urbanization Prospects, the 2014 Revision. Available: http://esa.un.org/unpd/wup/. ↩

  30. Jones Lang LaSalle & Pure Living China. (2015). Every breath we take – transforming the health of China’s office space. Available: http://www.joneslanglasalle.com.cn/china/en-gb/Research/indoor-air-quality-whitepaper.pdf?73310343-0858-4c2e-879a-6ffd99c22b1d. ↩

  31. Hsu, A., Reuben, A., Shindell, D… (2013). Toward the next generation of air quality monitoring indicators. Atmospheric Environment, 80, 561-570. ↩

  32. Wald, M. L. (2013, November 23). Power Plants Try Burning Wood With Coal to Cut Carbon Emissions. The New York Times. Available: http://www.nytimes.com/2013/11/04/business/power-plants-try-burning-wood.... ↩

  33. Gowen, A. (2015, December 4). India’s capital launches emergency plan to curb dire pollution. The Washington Post. Available: https://www.washingtonpost.com/world/asia_pacific/delhi-limits-drivers-t.... ↩

  34. AFP. (2014, May 8). India rejects WHO data showing Delhi air as world's dirtiest. The Economic Times. Available: http://economictimes.indiatimes.com/news/politics-and-nation/india-rejec.... ↩

  35. Central Pollution Control Board, Ministry of Environment & Forests. (2012). National Ambient Air Quality Monitoring Status and Trends in India - 2010. Available: http://www.cpcb.nic.in/upload/NewItems/NewItem_192_NAAQSTI.pdf. ↩

  36. Vashishtha, A. (2014, July 25). Govt to introduce pollution control index for measuring air quality in cities. India Today. Available: http://indiatoday.intoday.in/story/narendra-modi-government-pollution-co.... ↩

  37. British Broadcasting Corporation. (2015, April 6). India launches air quality index to give pollution information. Available: http://www.bbc.com/news/world-asia-india-32193742. ↩

  38. Hsu, A. & Yin, D. (2014, August 14). New Air Quality Index May Help India's Cities Breathe Easier. The Huffington Post. Available: http://www.huffingtonpost.com/angel-hsu/new-air-quality-index-may_b_5674.... ↩

  39. Burke, J. (2015, September 23). India's doctors blame air pollution for sharp rise in respiratory diseases. The Guardian. Available: http://www.theguardian.com/world/2015/sep/23/india-doctors-air-pollution.... ↩

  40. Bansal, G. & A. Bandivadekar. (2013). Overview of India’s Vehicle Emissions Control Program: Past Successes and Future Prospects. International Council on Clean Transportation. Available: http://www.theicct.org/sites/default/files/publications/ICCT_IndiaRetros.... ↩

Download the raw data for this chapter here.