Air pollution detected at some of the lowest levels in the US can prompt fatal heart attacks and strokes, according to alarming new findings published in the JAMA Open Network on Friday.
Authors of the study — one of the largest of its kind with data collected from 3.7 million Californians — blasted current federal regulations on air pollutants, arguing that they’re “not sufficiently protective.”
“We found that people exposed to fine particulate air pollution have an increased risk of experiencing a heart attack or dying from coronary heart disease — even when those exposure levels are at or below our current US air quality standards,” said lead author Stacey Alexeeff, a biostatistician at the Kaiser Permanente Division of Research, in a statement.
Alexeeff’s team evaluated the effects of fine particle air pollution, denoted as PM2.5 because the particles are 2.5 micrometers or less in diameter — small enough to pass through our lungs and translocate in the bloodstream. This type includes smoke, vehicle exhaust, power plant emissions and other byproducts of combustion.
The US Environmental Protection Agency regulatory standards for PM2.5 are 12 micrograms per cubic meter on average over the course of a year. As of 2021, the amount of PM2.5 in the air on a national level was between roughly seven and 11 micrograms per cubic meter on average, according to the EPA.
But even those exposed to fine particles at concentrations of 10 to 11.9 micrograms per cubic meter — below the federal standard — experienced a 6% increased risk of heart attack and a 7% increased risk of death due to cardiovascular disease. Further analysis concluded the risks remained at even lower concentrations of PM2.5 of 8 to 9.9 micrograms per cubic meter.
And despite current regulations, some localized cohorts within the participant pool endured well above the EPA’s safety guidelines. Researchers found that prolonged exposure to PM2.5 at 12 to 13.9 micrograms per cubic meter increased the risk of heart attack by 10%, and death from heart or cardiovascular disease by 16%.
“Our work has the potential to play an important role in ongoing national conversations led by the Environmental Protection Agency on whether — and how much — to tighten air quality standards to protect the public from pollution’s effects,” Alexeeff said.
Researchers analyzed data courtesy of California’s Kaiser Permanente health system, recorded between 2007 and 2016. Based on the patients’ addresses, who must have lived in the state for at least one year, the researchers estimated their average exposure to air pollution. Then, they discovered which patients were diagnosed with heart attacks or who had succumbed to heart and cardiovascular disease during the study period.
Kaiser’s thorough health records also allowed researchers to account for other cardiovascular risk factors among participants, such as smoking, body mass index and other associated illnesses, such as diabetes. “This allows us to be confident in our conclusion that fine particle air pollution has adverse associations with cardiovascular health,” said Dr. Stephen Sidney, a senior author of the study.
Their findings suggest that lowering the EPA standard to 10 micrograms per cubic meter or less would widely benefit the population.
“Our study clearly adds to the evidence that the current regulatory standards are not sufficient to protect the public,” Dr. Alexeeff said. “Our findings support the EPA’s analysis that lowering the standard to at least 10.0 micrograms per cubic meter is needed to protect the public. Our findings also suggest that lowering the standard to 8.0 micrograms per cubic meter may be needed to reduce the risk of heart attacks.”
The report follows a change in guidance from World Health Organization, which ruled in 2021 that exposure to PM2.5 should not exceed more than 5 micrograms per cubic meter on average annually. But last year, the WHO released data stating that a staggering 99% of the world is sucking in air pollutants at rates that exceed these goals.
Researchers also detected a link between socioeconomic status and air pollutant exposure, suggesting that certain neighborhoods were more at risk.
“The strongest association between exposure to air pollution and risk of cardiovascular events in our study was seen in people who live in low socioeconomic areas, where there is often more industry, busier streets, and more highways,” said Dr. Stephen Van Den Eeden, a research scientist and co-author of the study.
Previous studies have found that brief exposure to lesser-quality air could impair cognitive function, while others have observed spikes in obesity in areas where there is more air pollution.