During the first year of the Covid-19 pandemic, the world’s economy slowed. Yet, the global annual average particulate pollution (PM2.5) was largely unchanged from 2019 levels. At the same time, growing evidence shows air pollution—even when experienced at very low levels—hurts human health. This recently led the World Health Organization (WHO) to revise its guideline (from 10 µg/m³ to 5 µg/m³) for what it considers a safe level of exposure of particulate pollution, bringing most of the world—97.3 percent of the global population—into the unsafe zone.

The AQLI finds that particulate air pollution takes 2.2 years off global average life expectancy, or a combined 17 billion life-years, relative to a world that met the WHO guideline (5 µg/m³). This impact on life expectancy is comparable to that of smoking, more than three times that of alcohol use and unsafe water, six times that of HIV/AIDS, and 89 times that of conflict and terrorism.

“It would be a global emergency if Martians came to Earth and sprayed a substance that caused the average person on the planet to lose more than 2 years of life expectancy. This is similar to the situation that prevails in many parts of the world, except we are spraying the substance, not some invaders from outer space,” says Michael Greenstone, the Milton Friedman Distinguished Service Professor in Economics and creator of the AQLI along with colleagues at the Energy Policy Institute at the University of Chicago (EPIC). “Fortunately, history teaches us that it does not need to be this way. In many places around the planet, like the United States, strong policies, supported by an equally strong willingness for change, have succeeded in reducing air pollution.”

South Asia: In no region of the world is the deadly impact of pollution more visible than in South Asia, where more than half of the life burden of pollution occurs. Residents there are expected to lose about 5 years off their lives on average if the current high levels of pollution persist, and more in the most polluted regions. Since 2013, about 44 percent of the world’s increase in pollution has come from India.

Southeast Asia: Like South Asia, almost all of Southeast Asia (99.9 percent) is now considered to have unsafe levels of pollution, with pollution increasing in a single year by as much as 25 percent in some regions. Residents living in the most polluted parts of Southeast Asia—in the regions surrounding the cities of Mandalay, Hanoi and Jakarta—are expected to lose 3 to 4 years of life expectancy on average.

Central and West Africa: Similarly, almost all (more than 97 percent) of Central and West Africa is considered unsafe by the WHO’s new guidelines, with the AQLI finding that those living in the most polluted areas can expect to see their lives cut short by as much as 5 years on average. Air pollution is now as much of a health threat in Central and West Africa as well-known killers in the region like HIV/AIDS and malaria, as fossil fuel use is only expected to grow.

China: While China has a long way to go in its pollution battle—with residents potentially gaining 2.6 years of life expectancy on average if the country met the WHO guideline—the country has steeply cut its pollution year-on-year since it imposed a “war against pollution” in 2013. The year 2020 was no exception. Pollution fell by almost 40 percent between 2013 and 2020—adding about 2 years onto average life expectancy—and by about 9 percent from 2019 to 2020. While much of the world has seen a rise in pollution in recent years, global pollution has decreased due entirely to China’s impact since 2013. Without China’s significant decline in pollution, global average pollution would have increased in that time.

United States and Europe: Sustained enforcement of strong air pollution policies in the United States and Europe have significantly reduced particulate pollution. But new evidence of the effect of even low levels of pollution on health reveals that now almost all of the United States and Europe—92.8 (up from 7.6) and 95.5 (up from 47.2) percent, respectively—do not meet the WHO’s new guideline. If pollution were to meet the new WHO guideline, 68 million life-years in the United States and 527 million life-years in Europe could be saved. The largest benefits from improved pollution in the United States and Europe are concentrated in specific areas such as California’s Mariposa County—threatened by historic wildfires in recent years—and Eastern Europe.

“By updating the AQLI with the new WHO guideline based on the latest science, we have a better grasp on the true cost we are paying to breathe polluted air,” says AQLI Director Christa Hasenkopf. “Now that our understanding of pollution’s impact on human health has improved, there is a stronger case for governments to prioritize it as an urgent policy issue.”