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Air pollution linked to irregular heartbeat and blood clots in lung

Posted Jun 05 2014 10:06am

A new study has found that air pollution is linked to an increased risk of developing an irregular heartbeat, which is a risk factor for strokeAny sudden neurological problem caused by a bleed or a clot in a blood vessel., and bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. clots in the lung. However, the research suggests that the direct impact of air pollution on the risk of heart attackThe death of a section of heart muscle caused by an interruption in its blood supply. Also called a myocardial infarction. and stroke is rather less clear.

Current evidence suggests that high levels of certain air pollutants are associated with a higher risk of cardiovascular problems, but it is not clear why this is. The new research therefore set out to explore the short term biological impact of air pollution on cardiovascular diseaseDisease of the heart and blood vessels, usually due to atherosclerosis., using data from three national collections in England and Wales for the period 2003-9.

These were the Myocardial Ischaemia National Audit Project (MINAP), which tracks hospital admissions for heart attack/stroke; hospital episode statistics (HES) on emergency admissions; and figures from the Office of National Statistics (ONS) on recorded deaths.

Some 400,000 heart attacks recorded in MINAP; more than 2 million emergency admissions for cardiovascular problems; and 600,000 deaths from a heart attack/stroke were linked to average levels of air pollutants over a period of 5 days using data from the monitoring station nearest to the place of residence.

Air pollutants included carbon monoxideA highly poisonous gas produced by incomplete combustion (burning), for example by faulty boilers or wood stoves, car exhaust fumes or tobacco smoke., nitrogen dioxide, particulate matter (PM10 and PM2.5), sulphur dioxide, and ozone. Information on ambient daily temperatures, recorded by the UK Meteorological Office, was also factored in.

No clear link with any air pollutant was found for cardiovascular deaths, with the exception of PM2.5 which was linked to an increased risk of irregular heart rhythms, irregular heartbeat (atrial fibrillationA common abnormal heart rhythm causing a rapid, irregular pulse and failure of the upper chambers of the heart (atria) to pump properly. Abbreviated to AF.) and blood clots in the lungs (pulmonary embolismObstruction of the pulmonary artery by a blood clot.). Only nitrogen dioxide was linked to an increased risk of a hospital admission for cardiovascular problems, including heart failureFailure of the heart to pump adequately., in the MINAP data.

The findings prompt the researchers to conclude that there is no clear evidence to link short term exposure to air pollution with an increased risk of heart attacks and stroke. However,  there does seem to be a clear link between particulate matter levels and heightened risk of atrial fibrillationAbnormally fast and uneven contractions of the muscle of the atria in the heart, so that blood cannot be pumped efficiently and pulmonary embolism.

The results of the study are published online in the journal Heart.

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