Long-term Air Pollution Ups Risk of CVD: European Study

Marlene Busko

January 27, 2014

ROME, ITALY — A large meta-analysis of 11 cohorts in five European countries suggests that long-term exposure to air pollution is a cardiovascular risk factor and current standards for air quality in Europe are not strict enough[1].

Individuals who lived in an area where they breathed in large concentrations of particles of polluted air over a long period had a greater risk of having a first acute coronary event (MI or unstable angina).

This association was seen even when the number of fine particles in the air was below the current European threshold for acceptable air quality.

The findings, from the European Study of Cohorts for Air Pollution Effects (ESCAPE), were published online January 21, 2014 in BMJ.

"Our study suggests an association between long-term exposure to particulate matter and incidence of coronary events," the researchers, with lead author Giulia Cesaroni (Lazio Regional Health Service, Rome, Italy), write. "The results of this study, together with other ESCAPE findings, support lowering of European limits for particulate air pollution to adequately protect public health," they conclude.

According to the recent report on the Global Burden of Disease, particulate air pollution is estimated to cause 3.1 million deaths each year worldwide, but the effect of air pollution on the incidence of acute MI and unstable angina was unclear, the authors write.

In the European Union, the current annual limit for fine particulate matter with a diameter of <2.5 µm (PM2.5) is 25 µg/m3, which is more than twice as high as the acceptable level in the US, at 12 µg/m3.

The researchers sought to estimate the association between long-term exposure to air pollution—fine particles, coarse particles, soot, and nitrogen oxide—and the subsequent incidence of acute coronary events.

ESCAPE included 100 166 participants who were enrolled in cohorts in Finland, Sweden, Denmark, Germany, and Italy from 1997 to 2007 and had no previous coronary events at baseline.

During a mean follow-up of 11.5 years, 5157 participants had an incident acute coronary event.

In statistical models that adjusted for age, sex, year of enrollment, smoking, and socioeconomic factors, the researchers found that a 5-µg/m3 increase in annual exposure to fine (PM2.5) particulate matter was associated with a 13% increased risk of coronary events, and a 10-µg/m3 increase in annual exposure to coarse (PM10) particulate matter was associated with a 12% increased risk of coronary events.

In an accompanying editorial[2], Drs Michael Brauer and John Mancini (University of British Columbia, Vancouver) note that the study showed that, "significant effects [on cardiac events] were also discernible for exposure levels only slightly above the 10-µg/m3World Health Organization [WHO] air-quality guideline" for fine particles, and nearly 90% of the world's population is exposed to levels of air pollution that exceed this recommended maximum threshold. For example, a recent study showed that in Beijing, levels of fine particles in the air were more than 10 times as high as this over a five-year period[3].

Brauer and Mancini call for more efforts to reduce other known cardiovascular risk factors, such as smoking, in highly polluted areas. In addition, "people with or at risk of cardiovascular disease who live in highly polluted areas might warrant more aggressive use of primary and secondary preventive therapies, including antiplatelet agents, lipid-lowering agents, and treatments for hypertension or diabetes, all known to prevent cardiovascular events," they write.

The original studies in the meta-analysis received funding from the European Community's Seventh Framework Program. The authors have reported they have no conflicts of interest. The editorialists have reported they have no relevant financial relationships.

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