Air pollution linked to heart diseases

December 1, 2017

It is time to start paying more attention to the role of air pollution levels and heart diseases.

There is a wider agreement within medical researchers that people exposed to higher levels of air pollution have a greater risk of stroke, heart attacks and cognitive deterioration.

Recently researchers from the University of Edinburgh and universities in the Netherlands studied extremely small particles of inert gold - at a similar size to those found in diesel exhaust fumes. Scientists asked 14 healthy volunteers to breathe in air containing pieces of gold, which scientists consider inert, while exercising for two hours. A day later, researchers found that gold nanoparticles had made their way into the bloodstream of most participants. Scientists suggest this shows that nanoparticles of pollution have the potential to make a similar journey into the body, reports BBC.

Researchers speculate that by accumulating in vulnerable areas of the body air pollution particles could worsen heart disease and stroke. Earlier the Global Burden of Disease study in the Lancet has described the worldwide impact of air pollution with as many as 3.1 million of 52.8 million all-cause and all-age deaths being attributable to ambient air pollution in the year 2010. A longitudinal cohort study published in The Lancet in 2016 showed association between air pollution and coronary artery calcification.

The study found that increased concentrations of PM2.5 and traffic-related air pollution within metropolitan areas, in ranges commonly encountered worldwide, are associated with progression in coronary calcification, consistent with acceleration of atherosclerosis.

This study supports the case for global efforts of pollution reduction in prevention of cardiovascular diseases. Moreover, ambient air pollution ranked ninth among the modifiable disease risk factors, being listed above other commonly recognized factors, such as low physical activity, a high-sodium diet, high cholesterol, and drug use.

One of the first studies that supported the association between ambient air pollution and cardiovascular disease was the Netherlands Cohort Study on Diet and Cancer which was initiated in 1986 with the purpose of investigating the association between diet and cancer. The study established an enduring positive association between long-term exposure to air pollution and total and cardiovascular mortality, mainly due to coronary artery disease.

Studying the links between air pollution and health is difficult, since so many factors are involved and it is difficult to establish a direct cause-and-effect relationship. But a link between pollutants in the air and declines in cardiovascular health has been suspected since at least 1952 London Smog. 

British official estimates at the time put the number of fatalities at 4,000 – more civilian casualties than were caused by any single incident during the war – while recent research suggests that it may have caused as many as 12,000 death in the following weeks from exposure to the noxious air pollution, according to BBC report.  In 1956, British government passed the Clean Air Act came, banning the burning of polluting fuels in smoke control areas in UK.

In the 1990s, epidemiological research suggested that breathing in tainted air drives up rates of heart disease.  A team of scientists studied short-term impact of air pollution by studying 1,705 stroke victims admitted to Beth Israel Deaconess Medical Center in Boston from 1999 to 2008, examining medical records to obtain the precise time a stroke actually occurred.

They then cross-checked with the Environmental Protection Agency’s air quality index, which rates pollution levels in six general categories, beginning with “good,” then “moderate” and, at the very worst, “hazardous.”

The researchers found a 34 per cent higher risk at times when pollution levels climbed from “good” to “moderate.” The effect was particularly strong when the researchers looked at levels of so-called black carbon and nitrogen dioxide, two markers of pollution from traffic.

But despite many studies, exactly how air pollution affects the heart is not fully understood.