The index estimates the number of years a country could add to its people’s lives by meeting national or WHO standards for PM2.5 – particulate matter less than 2.5 microns in size, or 30 times finer than a human hair, which, when inhaled, can enter deep into the lungs and sometimes the bloodstream to cause serious harm.
Among India’s most populous cities, the National Capital Territory (NCT) of Delhi would make the most impressive gains in average life expectancy (nine years), followed by Agra (8.1 years) and Bareilly (7.8 years).
By providing the actual impact on lifespans, AQLI goes a step beyond India’s National Air Quality Index (AQI), which measures the presence of eight pollutants in the air and ranks their levels into six categories of severity.
AQLI shows that by reducing PM 2.5 pollution to below the Indian standard – as set by the Central Pollution Control Board, and less stringent than the WHO standard – Indians could live 1.35 years longer on average.
The WHO standard for permissible levels of PM 2.5 in the air (annual) is 10 micrograms per cubic metre (μg/m3), but India’s National Ambient Air Quality standard for PM 2.5 is four times higher at 40 μg/m3.
Michael Greenstone, director of the Energy Policy Institute at the University of Chicago, responding to IndiaSpend in an email, said:
The WHO assigns such a low standard precisely because small particulate pollution have been shown to have negative impacts on health even at very low levels.
The NCT of Delhi, with an estimated population of 15.5 million, recorded an annual mean of 98 μg/m3, more than twice the limit considered safe under the National Ambient Air Quality standard and almost 10 times the WHO standard.
Delhi stands the most to gain from controlling PM 2.5 pollution, with citizens adding nearly six years (5.9) to their lives if national standards are met, and nine years if WHO norms are met.
The AQLI is based on data from studies published in the Proceedings of the National Academy of Sciences, a peer-reviewed scientific journal, which found that a 10 μg/m3 increase in airborne particulate matter of 10 microns in size (PM10) reduces life expectancy by 0.64 years.
This PM10 estimate was then applied to global PM2.5 concentrations.
Estimates of ambient PM 2.5 concentrations around the world during the year 2015 were taken from the Atmospheric Composition Analysis Group at the Dalhousie University, Canada, which had used a combination of satellite, physical monitoring and simulation-based sources to collect this data.
These measurements exclude dust and sea-salt, considered natural sources of PM2.5, so that the concentrations shown in the map depict pollution resulting principally from human activity.
The Way Forward
In 2015, 92 percent of the world’s population lived in areas that exceeded the annual PM 2.5 safe limit of 10 µg/m3 prescribed by the WHO, according to the first State of Global Air report prepared in 2017 by the US-based Global Burden of Disease Project and Health Effects Institute.
Nearly all (86 percent) of the most extreme concentrations (above 75 µg/m3) were recorded in China, India, Pakistan and Bangladesh.
The same year, exposure to PM 2.5 was the fifth-highest risk factor for death, responsible for 4.2 million deaths from heart disease and stroke, lung cancer, chronic lung disease, and respiratory infections, according to data from the Global Burden of Disease project.
More than 50% of these deaths occurred in China and India, and India is now close to China in terms of deaths attributable to PM 2.5. At 1.1 million, China recorded the most mortality attributable to PM 2.5.
Despite evidence to the contrary, the Indian government has denied links between air pollution and premature deaths.
“There are no conclusive data available in the country to establish direct co-relationship of death exclusively with air pollution,” the Ministry of Environment, Forests and Climate Change told the Rajya Sabha, on 6 February.
“Air pollution could be one of the triggering factors for respiratory associated ailments and diseases,” it said, enumerating among other factors people’s food habits, occupational habits, socio-economic status, medical history, immunity and heredity.
The scientists behind AQLI, however, believe there is new evidence that proves a direct link.
Speaking to IndiaSpend and explaining the results of research his team undertook in parts of China that led them to build the index, Michael Greenstone said:
It is telling that the reduction in life expectancy is entirely due to cardiorespiratory causes of death as this strengthens the case that air pollution is the cause. In contrast to most previous work, the study’s context (China) is particularly well suited for extrapolation to India because of the similarities in the countries’ pollution levels and economic conditions.
Greenstone said there are “tremendous opportunities available” for India to reduce concentrations of PM2.5 and other pollutants, including market-based approaches to regulation such as cap-and-trade programmes that could “greatly reduce the costs of regulation to industry and, at the same time, reduce air pollution.”
India’s Bureau of Energy Efficiency already runs one such market-based programme called Perform, Achieve and Trade (PAT) that enables businesses to trade energy efficiency certificates.
Those that exceed their targeted energy savings sell certificates to those who fail to achieve their targets.
(Mukta Patil is an analyst with IndiaSpend. This article was first published on IndiaSpend and has been republished with permission)
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