Long-term exposure to fine particle air pollution is a major risk factor for heart disease and death, but even small reductions in pollution levels can reduce the threat, a new study shows.
Researchers analyzed data from more than 157,000 adults, aged 35 to 70, in 21 countries.
Between 2003 and 2018, more than 9,100 people had heart disease events, including more than 4,000 heart attacks and more than 4,100 strokes. More than 3,200 deaths were attributed to heart disease.
For every 10 microgram-per-cubic-meter increase in PM2.5 pollution, heart events rose 5 percent, the study found. PM2.5 pollution is caused by airborne particles under 2.5 microns in size.
After factoring in in the wide range of PM2.5 levels worldwide, researchers concluded that 14 percent of the documented heart events were linked to PM2.5 exposure.
"That's a big number," said study lead author Perry Hystad, an environmental epidemiologist at Oregon State University in Corvallis. "That's a substantial portion of the cardiovascular disease burden."
The strongest link between air pollution and heart disease risk was for strokes, Hystad said.
PM2.5 particles are produced by combustion sources such as car engines, fireplaces and coal-fired power plants. They're small enough to be breathed deep into the lungs where they can cause chronic inflammation, Hystad said.
The good news is that heart health stands to benefit from any improvement in pollution levels, according to the authors of the study published in the June issue of The Lancet Planetary Health journal.
"If you reduce the concentration of outdoor air pollution, you're going to see benefits for cardiovascular disease," Hystad said. "Before this study, we were not sure if this was the case. Some studies suggested that at high concentration, as seen in many developing countries, levels would have to be reduced by very large amounts before health benefits would occur."
The American Heart Association has more on air pollution and the heart.
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