California particle pollution linked to heightened risk of heart attack: study

Californians living with long-term exposure to air pollution may experience an increased risk of having a heart attack or dying from heart disease, a new study has found.

Individuals facing the biggest threat from such fine particle pollution — emitted by vehicles, smokestacks and fires — typically live in under-resourced communities, according to the study, published on Friday in JAMA Network Open.

The risk of enduring a heart attack or dying from heart disease rose “even when those exposure levels are at or below our current U.S. air quality standards,” lead author Stacey Alexeeff, a research scientist at Kaiser Permanente, said in a statement. 

To draw their conclusions, Alexeeff and her colleagues combed through data from 3.7 million adults who were members of Kaiser Permanent in Northern California from 2007 through 2016 and had lived in the state for at least a year.

The researchers then tied each person’s address to a specific geographical location, to establish annual average exposure to fine particulate pollution.

They then identified which patients had been diagnosed with a heart attack and which had died from heart or cardiovascular disease.

The Environmental Protection Agency’s (EPA) current regulatory standard for fine particle air pollution — also known as PM 2.5 — is 12 micrograms per cubic meter on average, over a year, the authors noted.

They found that exposure to PM 2.5 at concentrations between 12 and 13.9 micrograms per cubic meter was associated with a 10-percent increased risk of experiencing a heart attack and a 16-percent increased risk of dying from cardiovascular disease — in comparison to exposures under 8 micrograms per cubic meter.

But the authors also identified heightened risks of heart attack and death from heart disease at concentrations well below the EPA’s regulatory standard.

The researchers observed a 6-percent increased risk of heart attack and 7-percent increased risk of death from heart disease in adults exposed to PM 2.5 at levels of 10 to 11.9 micrograms per cubic meter — again compared to exposures under 8 micrograms per cubic meter.

Last month, the EPA released a proposal to reduce the annual PM 2.5 standard to between 9 and 10 micrograms per cubic meter, stressing that current regulations did not meet Clean Air Act public health guidelines, the authors noted.

Because Alexeef and her colleagues found that heightened risk of heart attacks persisted even at concentrations of 8 to 9.9 micrograms per cubic meter, they suggested that the new standard be decreased to 8 micrograms per cubic meter.

“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,” Alexeef said.

In addition to exploring the levels of PM 2.5 that contribute to heart attack risk, the researchers also determined that socioeconomic status was linked to pollution exposure and cardiovascular disease development.

They observed the strongest such link “in people who live in low socioeconomic areas, where there is often more industry, busier streets, and more highways,” co-author Stephen Van Den Eeden, also a research scientist at Kaiser Permanente, said in a statement.

“Neighborhood matters when it comes to exposures to this type of air pollution,” Van Den Eeden added.