New research examines the link between exposure to air pollution and the risk of coronary artery calcification among Chinese adults.

Studies have linked air pollution with the risk of developing a range of conditions, from neurological disorders such as Parkinson's disease and Alzheimer's to diabetes and atherosclerosis, which is the hardening of the arteries.

For instance, early last month, Medical News Today reported on a study by researchers at the University at Buffalo School of Public Health and Health Professions in New York, which linked long-term exposure to air pollution with the risk of atherosclerosis in six cities across the United States.

Now, the same lead author, Meng Wang, has carried out similar research in China, making this new study the first to examine pollution and coronary artery calcification among Chinese adults.

Wang and team set out to examine whether "air pollution and proximity to traffic" correlate with coronary artery calcium score, a key marker of atherosclerosis. Atherosclerosis refers to the buildup of plaque inside the artery walls, which, over time, may lead to serious cardiovascular conditions, such as high blood pressure, heart disease, and heart attacks. Wang and team published their findings in the journal JAMA Network Open.

Studying air pollution and artery health

Wang and colleagues examined data on 8,867 Chinese people aged between 25 and 92 years. The participants all had suspected coronary heart disease, and the team recruited them in 2015–2017.

The researchers assessed the coronary artery calcium and coronary heart disease score of each participant and excluded anyone who had had a myocardial infarction, stenting procedure, or coronary artery bypass surgery in the past. They also excluded those for whom the data on risk factors and exposure to pollution were insufficient.

Wang and team estimated the annual levels of pollution at the participants' residences by calculating their nitrogen dioxide, ozone, and fine particulate matter levels using a standard geostatistical prediction model.

In this case, fine particulate matter (PM2.5) describes particles with an aerodynamic diameter smaller than 2.5 micrometers that are very easy to inhale. Particulate matter, or particle pollution, refers to "a mixture of solid particles and liquid droplets," including "dust, dirt, soot, or smoke," that can be present in the air and that a person cannot see with the naked eye. In the new study, the researchers also estimated the participants' proximity to traffic, looking at the distance of their residences from nearby roads.

Pollution may raise heart disease death risk

The research revealed that for each nitrogen dioxide increase of 20 micrograms per cubic meter (μg/m³), the risk of a high coronary artery calcium score rose by 24.5%.

Additionally, for each increase of 30 μg/m³ of PM2.5 that the participants had exposure to in their apartments, there was an increase of 27.2% in the coronary artery calcium score.

"This finding should contribute to an understanding of air pollutant effects worldwide, providing both much-needed, locally generated data and supportive evidence to inform the air pollution standard-setting process on a global scale," comments Wang.

"This study may provide evidence that coronary atherosclerosis is a pathological pathway through which air pollution exposure increases risk of death from coronary heart disease."

—Meng Wang

The lead author goes on to explain: "Atherosclerosis is a lifelong process. As such, the effects of air pollution exposure on atherosclerosis are likely to be chronic."

"Since more than 40% of all deaths are attributable to cardiovascular disease, the potential contribution of air pollutants to cardiovascular disease in China is very large," says the researcher, suggesting that "the current air pollution standard may need to be re-evaluated."