Introducing the Air Quality Life Index

Executive Summary

Particulate matter (PM) air pollution is the most deadly form of air pollution globally. Its microscopic particles penetrate deep into the lungs, bypassing the body’s natural defenses. From there it can enter the bloodstream, causing lung disease, cancer, strokes, and heart attacks. There is also evidence of detrimental effects on cognition. Yet, in spite of these risks, the relationship between particulate matter air pollution levels and human health is not widely comprehended by society at large. For most people, their only insight into particulate air pollution exposure and risk is the popular Air Quality Index, which uses a color-coded system to provide a normative assessment of daily air quality. But these colors do little to convey actual health risk, and are often accompanied by measurements of units that are unfamiliar to almost everyone (e.g., micrograms of pollution per cubic meter).

The Air Quality Life Index, or AQLI, represents a completely novel advancement in measuring and communicating the health risks posed by particulate matter air pollution. This is because the AQLI converts particulate air pollution into perhaps the most important metric that exists: its impact on life expectancy. The AQLI reveals that, averaged across all women, men, and children globally, particulate matter air pollution cuts global life expectancy short by nearly 2 years relative to what they would be if particulate concentrations everywhere were at the level deemed safe by the World Health Organization (WHO). This life expectancy loss makes particulate pollution more devastating than communicable diseases like tuberculosis and HIV/AIDS, behavioral killers like cigarette smoking, and even war.

Some areas of the world are impacted more than others. For example, in the United States, where there is less pollution, life expectancy is cut short by just 0.1 years relative to the WHO guideline. In China and India, where there are much greater levels of pollution, bringing particulate concentrations down to the WHO guideline would increase average life expectancy by 2.9 and 4.3 years, respectively.

The AQLI is rooted in peer-reviewed research that for the first time quantified the causal relationship between long-term human exposure to air pollution and life expectancy. The Index then combines this research with hyper-localized, global PM measurements, yielding unprecedented insight into the true cost of air pollution in communities around the world. For example, the average resident of Delhi will live about 10 fewer years because of high pollution, while those in Beijing and Los Angeles will live almost six and almost one fewer years, respectively.

Beyond these factors, the AQLI stands apart in a few important respects:

• The research underlying the AQLI is based on a setting with pollution at the very high concentrations that prevail in many parts of Asia today. Previous work has relied on extrapolations of associational evidence from the low levels in the United States from cigarette studies.
• The causal nature of the AQLI’s underlying research allows it to isolate the effect of air pollution from other factors that impact health. In contrast, previous efforts to summarize the health effects of air pollution have relied on associational studies that are prone to confounding the effects of air pollution with other determinants of human health.
• The AQLI delivers estimates of the loss of life expectancy for the average person. Other approaches report the number of people who die prematurely due to air pollution, leaving unanswered by how much these lives were cut short.
• The AQLI uses highly localized satellite data, making it possible to report life expectancy impacts at the county or similar level around the world, rather than at much more aggregated levels reported in previous studies.

In addition to its importance for typical individuals around the world, the AQLI can be an invaluable tool for policymakers. It can be used to measure, track, and illustrate the impact of pollution reductions, both in terms of air quality and life expectancy. For example, reductions in air pollution resulting in large part from the Clean Air Act have added more than 1.5 years to the life expectancy of the average American since 1970. The AQLI’s data also show that, more recently, three years into a “War on Pollution,” China has achieved large reductions in air pollution. If these improvements are sustained, the average resident there would see their life expectancy increase by 0.5 years.

The rest of this document lays out twelve facts about particulate air pollution and the AQLI. Section 1 provides basic background on particulate air pollution, its impacts on the human body, and its main sources. Section 2 lays out what researchers know and don’t know about particulate air pollution’s impact on health. Section 3 describes the AQLI and how it can be used. Finally, Section 4 uses the lens of the AQLI to unveil the gravity of the pollution threat to life expectancy, and where it is most severe.