Air Pollution Slightly Set the Heart Offbeat

Air pollution effects on cardiovascular events very small or nonexistent

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) Air pollution has been linked to a wide range of health problems, but it's not always clear what's directly related to specific air pollution measures.

A recent study compared various air pollution measures to various cardiovascular events.

Cardiovascular events are heart- or blood vessel-related incidents, such as heart attacks, strokes, atrial fibrillation and pulmonary embolism (blood clot in the lungs).

The results of this study did not reveal any strong links between air pollution measures and heart attacks.

Some links appeared for other cardiovascular events, but the increase in risk was very small.

"Discuss your cardiovascular risks with your doctor."

This study, led by Ai Milojevic, of the Department of Environmental Health Research at the London School of Hygiene and Tropical Medicine in the United Kingdom, looked at possible effects of air pollution on cardiovascular health.

The researchers first obtained data on a wide range of cardiovascular events, including more than 400,000 heart attacks, more than 2 million emergency room admissions related to a cardiovascular event and more than 600,000 deaths from cardiovascular causes.

These incidents were all compared to air pollution measures at the person's place of residence on the day the events occurred and the four preceding days, taking into account temperature and the day of the week since those factors may also influence cardiovascular events.

The air pollution measures including daily average concentrations of carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2) and particulate matter that was less than 10 micrometers (μm) and less than 2.5 μm in diameter.

The researchers also included the average amount of O3 (ozone) over an eight-hour period of time in their air pollution measures.

These researchers found that the only air pollution measure that was linked to cardiovascular deaths was the amount of particulate matter less than 2.5 μm in diameter.

Greater increases in 2.5 μm particulate matter in the air were linked to a small increase in arrhythmias, atrial fibrillation and pulmonary embolism (lung clots) events that resulted in death.

Arrhythmias and atrial fibrillation are both conditions involving irregular heart rates.

The only pollution measure associated with hospital admissions was the amount of nitrogen dioxide in the air, but this link was very small.

When the amount of nitrogen dioxide increased from the 10th percentile to the 90th percentile, there was a 1.7 percent increase in cardiovascular disease, a 2.9 percent increase in arrhythmias, a 2.8 percent increase in atrial fibrillation and a 4.4 percent increase in heart failure.

There was also a 2 percent increase in other cardiovascular disease events that were not heart attacks, but all of these increases are very tiny.

Similarly, nitrogen dioxide was linked to a very slight increased risk of heart attacks — a 3.6 percent increase — but only to "non-STEMI" heart attacks.

STEMI stands for ST segment elevation myocardial infarction, which is one of two types of heart attacks. STEMI are the more severe type.

The researchers found that, overall, air pollution levels appeared linked to pulmonary embolism but not to stroke or STEMI heart attacks.

In fact, the strongest links between air pollution and cardiovascular events were those not related to heart attacks.

"This study found no clear evidence for pollution effects on STEMIs and stroke," the authors wrote.

This study was published June 4 in the journal Heart.

The research was funded by the Policy Research Programme of the UK Department of Health. Additional funding came from the National Institute for Health Research and a Wellcome Trust Senior Research Fellowship in Clinical Science. The authors reported no conflicts of interest.

Review Date: 
June 4, 2014
Last Updated:
June 5, 2014