Even small amounts of air pollution cause potentially fatal heart attacks and strokes

OAKLAND, Calif. — Even exposure to small amounts of air pollution can lead to potentially fatal heart attacks and strokes, new research warns. A team from Kaiser Permanente says people encountering pollution levels below current U.S. air quality standards are still more likely to die from cardiovascular disease. The findings suggest that the world’s regulatory standards are not sufficiently protective and need further tightening. These results come from an analysis of 3.7 million adults in California — one of the biggest studies of its kind.

“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 U.S. air quality standards,” says lead author Stacey Alexeeff, PhD, a research scientist and biostatistician at the Kaiser Permanente Division of Research, in a media release.

“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.”

How do EPA guidelines compare to pollution levels making people sick?

The U.S. team looked at levels of fine particulate matter (PM2.5), the leading environmental risk factor for disease. Less than a fiftieth the width of a human hair, they get into the blood through the lungs, making it more sticky and triggering inflammation. The particles commonly come from diesel fumes, wood smoke, brake pads, tires, and road dust. The U.S. Environmental Protection Agency’s current annual regulatory standard for fine particle air pollution PM2.5 is 12 micrograms per cubic meter.

However, study authors found exposure at a concentration between 12.0 and 13.9 micrograms per cubic meter displays an association with a 10 and 16-percent increased risk of a heart attack and dying from heart or cardiovascular disease, respectively. This is in comparison to pollution concentrations of less than eight micrograms. In January, the EPA announced a proposal to reduce the acceptable level to between nine and 10 micrograms on the grounds that the public’s health does not have adequate protection against air pollution.

Smog, air pollution in Los Angeles
Afternoon summer smog obsuring office towers of Century City and Beverly Hills in Los Angeles. (© trekandphoto – stock.adobe.com)

Participants in the new study lived in California for at least a year. Researchers tracked them for up to a decade. Heart attack and heart disease mortality rates also rose by six and seven percent, respectively, among those exposed to moderate concentrations of 10 to 11.9 micrograms per cubic meter.

The findings suggest there would be health benefits if the new standard were 10 micrograms per cubic meter or less. Increased risk of heart attacks persisted even at concentrations of eight to 9.9, indicating that the U.S. would see fewer cases if the new standard was under eight micrograms. The study also linked living in poorer neighborhoods to pollution exposure and the risk of cardiovascular disease.

“We found strong evidence that neighborhood matters when it comes to exposures to this type of air pollution,” notes co-author Stephen Van Den Eeden, PhD, a research scientist at the Division of Research.

“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.”

Will this lead to an environmental policy change?

Study authors hope their findings in JAMA Network Open will influence ongoing policy discussions.

“Our study clearly adds to the evidence that the current regulatory standards are not sufficient to protect the public,” Dr. Alexeeff says. “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.”

Senior author Dr. Stephen Sidney describes the study as one of the largest to look at the impact of air pollution on heart disease.

“Importantly, Kaiser Permanente’s electronic health records made it possible for us to account for other factors that might increase a person’s risk of having a heart attack or developing cardiovascular disease, such as smoking status, body mass index, or having other illnesses, such as diabetes. This allows us to be confident in our conclusion that fine particle air pollution has adverse associations with cardiovascular health,” Dr. Sidney concludes.

Heart disease can develop when cholesterol builds up inside arteries, preventing the organ getting the blood and oxygen it needs. Cardiovascular disease covers all conditions that can affect the heart and blood vessels such as heart failure, stroke, and peripheral artery disease.

South West News Service writer Mark Waghorn contributed to this report.

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  1. It’s amazing how many non-peer reviewed studies are coming out to explain why there are so many excess strokes and heart attacks. Anything but the shots they coincide with.

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