Long term exposure to air pollution linked to heart attacks and angina

January 22nd, 2014 by British Medical Journal

Research conducted at the Department of Epidemiology in Rome, Italy and published in the paper ‘Long term exposure to ambient air pollution and incidence of acute coronary events’ on bmj.com suggests that long term exposure to particulate matter in outdoor air is strongly linked to heart attacks and angina, and this association persists at levels of exposure below the current European limits.

Traffic causes local air pollution in the narrow streets of St Peter Port (click image to expand - ©RLLord)

Traffic causes local air pollution in the narrow streets of St Peter Port (click image to expand – ©RLLord)

The results support lowering of the EU limits for particulate matter air pollution.

Ambient particulate matter air pollution is estimated to cause 3.2 million deaths worldwide per year, but the association between long term exposure to air pollution and incidence of coronary events remains controversial.

In the European Union the current annual limit for particulate matter with a diameter of 2.5 micrometres (μm) or less (known as PM2.5) is 25 µg per cubic metre, which is far above that implemented in the United States (12 µg per cubic metre).

A 2013 BMJ study found average PM2.5 concentrations over a five year period in Beijing was more than ten times the World Health Organization air quality guideline value of 10 µg per cubic metre.

An international team of researchers, coordinated by Utrecht University, Netherlands, set out to study the effect of long term exposure to airborne pollutants on acute coronary events (heart attack and unstable angina) in 11 cohorts participating in the European Study of Cohorts for Air Pollution Effects (ESCAPE).

The study involved over 100,000 people with no history of heart disease enrolled from 1997 to 2007 and followed for an average of 11.5 years.

Mathematical models were used to estimate concentrations of air pollution from particulate matter at each participant’s residential address.

A total of 5,157 participants experienced coronary events during the follow-up period.

After taking account of several other risk factors, including other illness, smoking, and socioeconomic factors, the researchers found that a 5 μg per cubic metre increase in PM2.5 particulate matter was associated with a 13% increased risk of coronary events and a 10μg per cubic metre increase in PM10 particulate matter was associated with a 12% increased risk of coronary events.

Particulate matter from a chimney in St Martin in the early evening of 11 January 2014 (click image to expand - ©RLLord)

Particulate matter from a chimney in St Martin in the early evening of 11 January 2014 (click image to expand – ©RLLord)

Positive associations were detected below the current annual European limit of 25 μg/m3 for PM2.5 and below 40 μg/m3 for PM10 and positive but non-significant associations were found with other pollutants.

Further analyses did not alter the results significantly.

“Our study suggests an association between long term exposure to particulate matter and incidence of coronary events,” the authors said.

They point out that these associations remained for exposure concentrations below the current European limits, and suggest that the burden of disease attributable to outdoor particulate matter “might be underestimated if only estimates of mortality are considered.”

The results of this study, together with other ESCAPE findings, “support lowering of European limits for particulate air pollution to adequately protect public health.”

Professors Michael Brauer and John Mancini from the University of British Columbia, in an accompanying editorial, ‘Where there’s smoke‘, said that this study “has specific relevance to the management of air quality in Europe.”

They also referred to the 2013 BMJ Beijing study and said “the important impact of air pollution on cardiovascular disease highlighted by these two papers supports efforts to meet existing and even more stringent air quality standards to minimise cardiovascular morbidity and mortality.”

 

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