Improvements In Air Pollution Offer Concrete Benefits In Terms Of Longer Lives: Michael Greenstone

Last week, a study on the impact of air pollution on life expectancy was undertaken by Michael Greenstone, the Milton Friedman Professor in Economics, the College, and the Harris School, as well as the Director of the Energy Policy Institute at the University of Chicago. A tool was also released by the organization called the Air Quality-Life Index (AQLI) which translates particulate air pollution into its impact on a person’s lifespan for every country. The tool finds that if India reduced its air pollution to comply with its national standards, its people could live more than 1 year longer, or a combined more than 1.6 billion life years. If the country complied with the more stringent World Health Organization’s air quality standard, its people could live 4 years longer, or a combined more than 4.7 billion life years. 

In an exclusive interview with BW Businessworld, Michael Greenstone discusses the study and the AQLI, elaborating on suggestions to improve air quality and increase life expectancy. Edited excerpts: 

1) What are the key findings of the study on the impact of air pollution on life expectancy?

The study has identified a credible way to measure the causal effect of long-run exposure to particulate air pollution on life expectancy, at the pollution levels that several billion people around the world (including in India and China) face. It estimates that a 10 μg/m3 increase in sustained exposure to airborne particulate matter reduces life expectancy by 0.6 years. These results indicate that particulates are the greatest current environmental risk to human health.

2) How does the Air Quality Life Index (AQLI) tool work in translating the impact of particulate air pollution on a human's lifespan for every country?

The AQLI combines grid-level estimates of population and pollution with the study's estimated effect of particulate matter exposure on life expectancy. This grid-level approach allows us to estimate life years saved by meeting WHO or national standards at different administrative levels for each country (e.g. districts in India) as well as for the entire country itself. More information about the data generating process for the AQLI can be found in the Data & Methodology section at the bottom of the AQLI’s web page.

3) What are the some of the suggestions in improving air quality to increase life expectancy?

Naturally, India is searching for the best way to balance the dual and, at times, conflicting goal of economic growth and a clean environment. The study highlights that improvements in air pollution offer concrete benefits in terms of longer lives. However, in too many instances, current policy imposes significant costs on industries without receiving sufficient pollution and health benefits. The least costly way to gain these health improvements is to pursue market-based regulatory approaches, like cap-and-trade for particulates that is built upon a foundation of reliable monitoring of industries. There are great opportunities for India to pursue regulatory policies that reduce air pollution, extend lives, and decrease the regulatory burden on industries.

4) How will compliance with national standards of air quality improve the quality of life for people?

Concentrations of particulate matter would be roughly 20% lower if India met its own national air quality standard, and would likely result in substantial short- and long-term health benefits. The findings of our study indicate that Indians would live about 1.3 years longer, on average, if its air quality standards were met. Other studies focusing on short-term benefits of lower particulate matter concentrations have found reductions in respiratory hospital admissions, mortality, and incidence of respiratory symptoms.

5) What is the difference between the national standard for air quality and WHO's standards for air quality?

India’s national PM2.5 standard is 40 μg/m3, whereas the WHO air quality guideline is 10 μg/m3. 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.

6) How was the AQLI built by employing a unique social setting in China?

The China study found that people living to the North of the Huai River, relative to people South of the river, face PM10 concentrations that are about 42 micrograms per cubic meter higher and live 3.1 years less. Together these findings indicate that an additional 10 micrograms per cubic meter of PM10 reduce life expectancy by 0.6 years. We then apply this relationship to global particulate air pollution data, including data from India.

7) What are the challenges and threats faced due to deteriorating air quality?

Without proper control mechanisms in place, India’s rapid economic growth and urbanization will be accompanied by a continued deterioration in air quality, and in turn, a further reduction in life expectancies. At the same time, current policies have imposed significant costs on industries with too few pollution and health benefits. Market-based regulatory approaches, such as cap-and-trade policies, can both lower the cost of reducing air pollution and help India balance its growing demand for energy with its public health goals.

8) What is the applicability of the AQLI tool in the Indian context?

As India balances, the urgent need for robust economic growth with the urgent need for public health, the AQLI provides a concrete measure of the benefits of reducing particulate air pollution in terms of longer lives. 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.