Despite Major Improvements, Levels of Air Pollution in the U.S. Are Still Unsafe

By Roberta Attanasio, IEAM Blog Editor

Air pollution not only threatens the future of our climate by significantly contributing to global warming, it also causes some of our most common illnesses, accounting for 1 in 8 deaths worldwide.  It’s an invisible killer that is globally responsible for 36% of deaths from lung cancer, 35% of deaths from pulmonary disease, 34% of deaths from stroke, and 27% of deaths from heart disease, according to the World Health Organization (WHO).

Although the problem is noticeably heightened in low- to middle-income countries, it’s still alarmingly present in high-income countries.  In the U.S., air quality started to improve with the Clean Air Act of 1963 and the establishment of the Environmental Protection Agency (EPA) in 1970.  The Clean Air Act amendments signed in 1990 required the EPA to set the National Ambient Air Quality Standards (NAAQS), or exposure limits, for six principal pollutants considered harmful.  The standards, which are periodically reviewed and can be revised, are necessary to protect the U.S. population—especially children, elderly people, and people affected by cardiovascular disease.  Hundreds of thousands of cases of serious health effects have been prevented each year by the implementation of the Clean Air Act and the NAAQS.

However, the “State of the Air 2017”, an in-depth report published by the American Lung Association that is based on air quality monitoring data collected in 2013 – 2015, found that despite continued improvements there is an unrelenting increase in dangerous pikes of fine particulate matter pollution. It also found that nearly four in 10 people in the U.S. live in counties with unhealthy levels of either ozone or fine particulate matter.

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Smog layer over Los Angeles (cropped from original). Credit: MinukCC BY-ND 2.0.

Results from a recent, comprehensive study published in the prestigious New England Journal of Medicine show that—even at levels below the current national standards—there is a strong correlation between increased risk of premature death and exposure to ozone and fine particulate matter.  In other words, the current standards may not be sufficient to protect the U.S. population from adverse effects.  Ozone, a gas that irritates lung tissues when inhaled, and fine particulate matter (or PM2.5, tiny particles of dust and soot measuring less than 2.5 µm that can lodge deeply in lung tissue), are two of the NAAQS six principal pollutants.  Both pollutants are produced as a result of emissions from vehicles, power plants, and other major sources of combustion.

In the NEJM study, scientists used data from federal air monitoring stations and satellites to compile a detailed picture of air pollution at the level of individual zip codes.  Then they analyzed the effects of very low levels of air pollution on mortality, using data from more than 60 million Medicare beneficiaries obtained between 2000 and 2012.  The results show that if the level of PM2.5 could be lowered by just 1 microgram per cubic meter nationwide, about 12,000 lives could be saved every year.  Similarly, if the level of ozone could be lowered by just 1 part per billion nationwide, about 1,900 lives would be saved each year.


Volume of air saturated each day by PM2.5 particles from heating boilers, from the NYC Clean Heat Project to map local air pollution. Credit: Carbon VisualsCC BY 2.0.

“This is a study of unprecedented statistical power because of the massive size of the study population.  These findings suggest that lowering the NAAQS for fine particulate matter will produce important public health benefits, especially among self-identified racial minorities and people with low incomes,” Francesca Dominici, principal investigator of the study, said in a press release.


Credit: Matt BrownCC BY 2.0.

Not surprisingly, an editorial that accompanies the published study calls for even tighter regulation of air pollution levels, pointing out that the current administration “is moving headlong in the opposite direction.”

Dominici told The  Washington Times: “Indeed, in the last 20 years we have been seeing the level of pollution going down quite dramatically. So what the paper is showing is we need to continue to take this issue very seriously.”  She added: “I can tell you for sure what we should not do, which is to take steps backwards toward this issue.”

The undergoing efforts to cut the EPA and roll back policies that limit environmental pollution and climate change may likely have the unfortunate effect of increasing the exposure levels of the U.S. population to air and other environmental pollutants that cause premature death.

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