Study finds “green” air quality rating can still affect your heart health
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With summer approaching, many will be looking to their weather apps for reassurance on air quality. A green dot usually tells us the air is good, or in other words, a level deemed safe by the Environmental Protection Agency (EPA). However, a new study from the University of Mississippi found that pollution levels well below the agency’s regulatory guidelines can still be dangerous to human health.
Researchers at the University of Mississippi analyzed decades of scientific papers looking at how low levels of PM2.5, particulate matter produced by traffic, industry and smoke, affect cardiovascular health. Specifically, they examined papers evaluating pollution levels that fall under those set by the EPA, which is currently capped at an annual average of 9 micrograms per cubic meter.
The review, published in Environmental Pollution, found that of the 95 studies analyzed from around the world, 67% showed significant links to cardiovascular issues. When looking specifically at the most harmful outcomes, 76% of the studies focusing on major events such as strokes and cardiovascular mortality found significant links to low-level pollution.
Researchers at the University of Mississippi believe that based on their findings, the EPA should re-evaluate current standards. “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,” said lead author and assistant professor of environmental toxicology Courtney Roper in a press release.
Vulnerable populations, including older adults, very young children, and those with a history of cardiovascular events, are at an increased risk of PM2.5-related health effects even at low levels, according to the study. Additionally, people of low socioeconomic status and non-white populations were also found to be particularly at-risk.
“The risk is also dependent upon the source of PM2.5,” said James Stewart, co-author of the study and associate professor of pharmacology at the University of Mississippi. “Whether it’s traffic pollution or manufacturing industrial pollution, or even rural pollution, where you have harvesting or plowing generating dust, that can impact human health on so many levels,” Stewart said in a press release.
The findings don’t surprise Dr. Philip Landrigan, a pediatrician and epidemiologist at Boston College who was not involved with the study. He points to the fact that the EPA’s annual standard for PM2.5 is nearly double the level recommended by the World Health Organization (WHO), which is a yearly average of 5 micrograms per cubic meter.
When it comes to daily exposure of PM 2.5, the WHO recommends a limit of 15 micrograms per cubic meter, less than half of the EPA’s limit of 35. Daily limits are higher to allow for temporary spikes.
“It’s known from well-conducted medical studies, epidemiological studies, that even below the WHO guideline of five, there’s still some risk,” Landrigan said, adding, “obviously, the risk gets less as the air pollution level gets lower, but almost any level of air pollution, almost all the way down to zero, convey some degree of risk,” he said.
Still, Landrigan believes implementing the WHO annual standard would avoid some of the worst health outcomes. “That would prevent many of the deaths from heart disease and stroke that are occurring even at the current legally permissible level of nine micrograms.”
The study’s findings come at a pivotal moment for air pollution policy in the US. Back in April, several states sued the EPA for failing to enforce clean air limits. An alliance of environmental and health groups, including the American Lung Association, also filed their own lawsuit to force the agency into compliance.
“EPA does not comment on external studies independent of the agency’s National Ambient Air Quality Standards (NAAQS) review process,” the EPA wrote in response to the study’s findings.
Landrigan believes the US is at a breaking point when it comes to regulating safe air.
“We’re at a point where we know much more about the dangers of air pollution at low levels, levels that we used to think were safe, we now know are not safe,” he said. “It is indeed time for a paradigm shift, and it’s time to reduce air pollution standards again, and I think we may not see it this year, but I think in the next few years we’re going to see that kind of a reduction.
Featured image: A. C. for Unsplash+
