That green air-quality dot may not really mean safe, study finds

Air quality readings that look favorable in a weather app may still come with hidden risks. 

New research suggests that pollution levels allowed under current U.S. regulations can still be associated with serious heart problems, challenging what qualifies as "safe," according to ScienceDirect.

A team of scientists at the University of Mississippi examined 95 air pollution studies from around the world, and compared exposures to low levels of particulate matter with adverse cardiovascular health outcomes. The team published its findings in the peer-reviewed journal of Environmental Pollution. 

The papers they reviewed all looked at pollution levels below the Environmental Protection Agency's limits. What the review found was startling: most of the studies still detected harm at those lower levels of particulate matter exposure. 

"Significant associations were observed between particulate matter exposure and adverse cardiovascular effects, even at levels deemed compliant with current regulations," the authors said. 

About 67% reported significant links to cardiovascular problems. Among the studies focused on the most severe outcomes, including stroke and cardiovascular death, 76% found significant links.

Taken together, the findings rightly led the researchers to question whether current standards are sufficiently protective.

The paper's lead author, Courtney Roper, said in a press release."If we were looking to make a regulation that was just focused on human health, our reviews suggest that the regulation should be lowered because we are seeing cardiovascular impacts." 

Even air that falls within federal limits may not be harmless, especially for people who are more vulnerable. The study found elevated risks from low pollution exposure for older adults, very young children, people who have previously had cardiovascular events, people with low socioeconomic status, and non-white populations.

Because current standards help guide everyday choices for millions of people deciding whether to spend time outside, they should be based on real-world data, and updated if new information is uncovered.

However, as reported by The New Lede, the EPA has given no sign that it plans to respond to the review.

The agency stated that "EPA does not comment on external studies independent of the agency's National Ambient Air Quality Standards (NAAQS) review process."

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