It has long been known that air pollution causes serious health problems; but a new epidemiologic study published in the medical journal Heart shows a new link between particulate matter in the atmosphere and heart diseases, like irregular heartbeat and lung blood clots.
Last year a WHO study reported air pollution killed around 7 million people worldwide every year (See: Air pollution kills 7 mn worldwide annually: WHO).
High levels of certain air pollutants can cause such cardiovascular concerns, but exactly how this association works has not been clarified.
Researchers set out to explore this idea using data from three national collections in England and Wales from 2003 to 2009: 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.
According to MINAP data, there were 400,000 heart attacks during this time period, 2 million emergency admissions for cardiovascular problems, and 600,000 heart attack and stroke deaths were related to average levels of air pollutants over a 5-day period.
Women who are exposed to significant levels of air pollution, especially during their second trimester, are more likely to give birth to children who have asthma, the researchers have determined.
In 2013 a worldwide study showed that pregnant mothers exposed to air pollution emitted by vehicles and coal power plants, are significantly more likely to have smaller babies (Air pollution results in mothers having smaller babies).
Air pollutants investigated included carbon monoxide, nitrogen dioxide, particulate matter (PM10 and PM2.5), sulfur dioxide and ozone.
The study showed that PM2.5 is clearly linked to a heightened risk of irregular heart rhythms, irregular heartbeat (atrial fibrillation) and blood clots in the lungs (pulmonary embolism). And only nitrogen dioxide was linked to more hospitalizations for cardiovascular problems, including heart failure, and an increased risk of a particular type of heart attack referred to as non-ST elevation.
Aside from these two findings, researchers revealed that there is no clear evidence implicating short term exposure to air pollution in boosting therisk of heart attacks and stroke.
An accompanying editorial, written by cardiologists from the University of Edinburgh, points out that particulate matter is thought to be responsible for more than 3 million deaths worldwide, primarily as a result of heart attacks and stroke.
Nevertheless, the relationship between the two is still hazy.
"The current lack of consistent associations with contemporary UK data may suggest that as the fog begins to clear, the adverse health effects of air pollution are starting to have less of an impact and are more difficult to delineate," authors concluded in a statement.
India is near the top of the table when it comes to polluted air, according to several studies; with Delhi and Mumbai topping the list (Delhi overtakes Beijing as world's most air-polluted city and Air quality worsening in India's major cities, finds TERI survey)
In 2012 a Harvard School of Public Health study had shown that older adults may be at increased risk of being hospitalised for lung and heart disease,
stroke, and diabetes following long-term exposure to fine-particle air pollution (Long-term exposure to air pollution may increase risk of hospitalisation for lung, heart disease)
University of Michigan researchers have shown long-term exposure to air pollution may be linked to heart attacks and strokes by speeding up atherosclerosis, or "hardening of the arteries," (Air pollution linked to hardening of the arteries)