If all countries met World Health Organization standards for fine particulate air pollution, life expectancy gains could be similar in scale to eradicating breast and lung cancer.

That’s according to a new study published this month in Environmental Science & Technology Letters that investigated the impact of ambient fine particulate matter air pollution, also known as PM2.5, on life expectancy around the world. Researchers estimated that in 2016, exposure to PM2.5 reduced average global life expectancy by about one year, with even greater regional impacts in countries with high levels of pollution. In the U.S., according to the study, the impact of PM2.5 on life expectancy is “substantially larger” than that of breast cancer, with the pollution costing the average person about four months of life.

Right now, researchers wrote, 95 percent of the world’s population live with PM2.5 levels that exceed WHO’s recommendations.

“Reducing air pollution in countries at all levels of economic development could lead to substantial gains in life expectancy, gains on par with reducing other well-recognized threats to public health,” researchers concluded.

Fine particulate matter pollution — that’s air pollution containing particulate matter smaller than 2.5 micrometers — comes from vehicles, power plants and activities that involve the burning of fuels, including oil, wood and coal. The pollution particles are so small, according to the New York State Department Health, “that several thousand of them could fit on the period at the end of this sentence.” Extensive literature finds that the tiny pollutants are associated with a number of adverse health effects, including higher rates of hospital admissions for respiratory and heart problems and a greater risk of premature death.

PM2.5 is also the kind of air pollution that would be scaled back under the Obama-era Clean Power Plan that the Trump administration is currently trying to repeal. In fact, in its proposal, the U.S. Environmental Protection Agency acknowledges that Trump’s rollback would increase PM2.5 pollution and cause up to 1,400 premature deaths each year.

To conduct the new PM2.5 study, researchers analyzed life expectancy and disease data for 185 countries from the Global Burden of Disease 2016, which contains billions of data points. They found that as PM2.5 went up, life expectancy went down. In particular, PM2.5 exposure reduced global life expectancy by just about one year. The impact varied across regions, with greater impacts in countries with more pollution.

For example, PM2.5 exposure was associated with a 1.87-year reduction in life expectancy in Bangladesh, a 1.85-year reduction in Egypt, 1.56-year reduction in Pakistan, 1.53-year reduction in India, 1.28-year reduction in Nigeria, a 1.48-year reduction in Saudi Arabia and a 1.25-year reduction in life expectancy in China. In regions where household air pollutants and PM2.5 are both considerable health hazards, the negative impact on life expectancy was even greater. In the U.S., the negative life expectancy impact from PM2.5 was bigger than that of breast cancer, while in South Asia, the impact of PM2.5 exceeded the combined life expectancy impacts of all cancers.

Researchers said the findings expand the evidence base on how air pollution “substantially reduces human longevity.”

“In short, the burden of disease from air pollution results in life expectancy decrements of a magnitude similar to those of other high-priority risk factors and diseases,” researchers wrote.

According to WHO, about 7 million people die each year from exposure to fine particle pollution, which can lead to stroke, heart disease, lung cancer, respiratory disease and infections. In the U.S., according to the American Lung Association, 41 percent of the population lives in counties with unhealthy levels of air pollution. For a copy of the new PM2.5 study, visit Environmental Science & Technology Letters.