More than 30,000 deaths have been linked to poor air quality in the United States, according to new research funded by the Environmental Protection Agency (EPA). And even at levels considered to be safe, researchers argue that air pollution can increase mortality rates.

The study, released Tuesday, was also supported by the research charity Wellcome Trust, and reinforces long-running concerns over microscopic pollution particles in the air and their impact on human health. It also widens the gap between the Trump administration’s efforts to rollback clean air rules and the government’s own findings on the importance of air quality.

Researchers from Imperial College London and Carnegie Mellon University’s Center for Air, Climate, and Energy Solutions authored the new study, published in PLOS Medicine, which probes the impacts of air pollution across the contiguous United States from 1999 to 2015. At the center of the study is PM2.5, atmospheric particulate matter with a diameter of less than 2.5 micrometers — 30 times smaller than the width of a human hair.

These particles typically come from sources like power plants and cars, and are so tiny that they can travel deep into the lungs, risking various health problems like cancer and lung disease. The current national standard is 12 micrograms per cubic meter of air (ug/m3) but Tuesday’s study shows that might not be strict enough — while PM2.5 has declined nationally since 1999, the researchers found that PM2.5 levels as low as 2.8ug/m3 are associated with an uptick in deaths.


Majid Ezzati from Imperial’s School of Public Health and the study’s lead author, said in a statement that the research has jarring implications for the current EPA air quality standard.

“We’ve known for some time that these particles [PM2.5] can be deadly. This study suggests even at seemingly low concentrations — mostly below current limits — they still cause tens of thousands of deaths,” said Ezzati.

Using a combination of satellite imagery, data from over 750 U.S. air quality monitoring stations, and the National Center for Health Statistics, the researchers found that air pollution deaths examined in 2015 totaled more than 30,369. That data, which used binary gender, broke the total number down to 15,612 women and 14,757 men, and noted that they died from cardiorespiratory conditions like asthma or heart attacks.

Region and class status seemingly played a role in the deaths as well. Some areas were more prone to high PM2.5 concentrations and associated mortality, including Los Angeles, California, and a number of Southern states, like Arkansas and Alabama.


Imperial College London also notes that at any concentration of PM2.5, “life expectancy loss was, on average, larger in counties with lower income than in wealthier counties.” Prior EPA-funded studies have shown that black and Latinx Americans also disproportionately suffer from poor air quality.

The researchers said their analysis highlights the dangers of fine particulate matter even at low levels and argued that shifting the national standard could save lives.

“Lowering the PM2.5 standard below the current level is likely to improve the health of the U.S. nation, and reduce health inequality,” said Ezzati.

That advice comes as the Trump administration continues to push forward with an onslaught of regulatory rollbacks at the EPA — many of which are specifically aimed at undoing clean air rules.

The agency’s head, Andrew Wheeler, has targeted the 2011 Mercury and Air Toxics standards, or MATS, which seek to curb pollution from coal and oil-burning plants.


Moreover, the administration is embroiled in a war with California over its clean air waiver, which allows the state to impose its own vehicle emissions standards. Those requirements are stricter than their federal equivalent and have helped improve air quality, but under President Donald Trump the EPA has sought to revoke the waiver while standardizing policies nationwide.

Meanwhile, even as air quality has improved nationally over the course of several decades, it has declined since Trump took office, according to the EPA. The agency’s Air Quality Index (AQI) shows that air quality has slightly decreased from 2016 to 2018, even as totals remain far better than in the period between 2010 and 2012 — the last time the country topped 1,000 days with air deemed “unhealthy for sensitive groups.”

CREDIT: EPA

Another emerging issue for air quality, however, is climate change.

Tuesday’s study comes at the same time as new research from the University of Delaware finds that rising global temperatures will increase the number of days with high concentrations of ground-level ozone in the Mid-Atlantic region of the United States.

Like PM2.5, ozone — also known as smog — is linked to respiratory problems and reduced lung function. While ozone pollution has been declining in Delaware specifically, the research shows that rising temperatures are “threatening to reverse the decrease” of the trace gas in the area.

But while research has found that air pollution can actually assist with global cooling by helping to reflect sun away from the Earth, critics of the Trump administration’s policies argue that the combination of regulatory rollbacks around issues like air quality, coupled with active skepticism around climate science, is harming public health and the environment. And both studies out this week highlight the very contemporary dangers of poor air quality.

Meanwhile, the EPA’s air quality office itself is likely to remain at the center of controversy after its former head Bill Wehrum resigned abruptly last month.

Ethics watchdogs have long accused Wehrum, a former lobbyist who sought weaker air standards, of remaining close to his former clients while simultaneously unraveling air quality standards at the EPA. On Monday, the agency’s internal watchdog acknowledged that Wehrum is facing a new ethics inquiry.