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How does air pollution lead to heart diseases?

Researchers at the University of Edinburgh and Universities in the Netherlands have finally unearthed the reason behind air pollution leading to heart diseases. Tiny particles, also known as nanoparticles, could potentially be so small that the body's filter system in the nose and lungs might prove incompetent to remove it. The particles could then build up in blood vessels and raise the risk of a heart disease.

Air pollution has been linked to heart diseases and premature deaths of millions. Most of these deaths are due to a heightened risk of cardiovascular disease, which means that being exposed to high pollution even for short periods can trigger heart attacks and strokes. On the other hand, long-term exposure causes vascular damage.

According to figures estimated by the government, air pollution, which has remained illegally high in 16 cities since 2010, is responsible for the premature deaths of about 40,000 Britons every year. And heart disease is considered Britain’s biggest killer, resulting in over 160,000 deaths each year.

The research team got 14 healthy volunteers and 12 surgical patients to inhale harmless nanoparticles of gold. Test results of on their blood and urine showed the nanoparticles in just 15 minutes of being inhaled, and they were still present up to three months later.

Even though it was suspected, the possibility of the nanoparticles to pass through the lungs into the bloodstream had never been proved. The nanoparticles of pollution are mostly carbon compounds, and finding them inside carbon-based life forms like ourselves is extremely tough.

In another experiment, researchers asked three patients, who had clogged-up blood vessels, to inhale air that contained tiny gold nanoparticles. A day later, a part of their damaged blood vessels surgically removed from the patients, there was evidence that gold had built up in the plagued parts of the blood vessels. Researchers speculate that by accumulating in vulnerable areas of the body, air pollution particles could worsen heart disease and stroke.

Gold nanoparticles are inert, but the reactive compounds found in air pollution can have various kinds of harmful effects. It includes impairing the contraction of blood vessels to promote clotting.

Diesel cars have been touted since the 1970s as an environment-friendly choice because they emit comparatively less carbon dioxide. Carbon dioxide is a greenhouse gas which is responsible for global warming. Successive governments have put tax incentives on diesel cars, allowing drivers to pay less vehicle excise duty.

But scientists have realized in recent years that diesel does produce more of the nanoparticles and nitrogen oxides that are harmful to the human health.

Breathing in fumes from traffic exhaust has long been known to raise the risk of cardiovascular disease, but the reason has remained unclear. Another study in the US involving more than 6,500 adults, found it was because pollution reduces our beneficial cholesterol HDL (high-density lipoprotein) which is then unable to do its job of removing bad LDL (low-density lipoprotein) from the body.

Professor Jeremy Pearson, British Heart Foundation’s associate medical director, said the study added to the case for the Government to start taking steps to reduce air pollution. “There is no doubt that air pollution is a killer, and this study brings us a step closer to solving the mystery of how air pollution damages our cardiovascular health. More research is needed to pin down the mechanism and consolidate the evidence, but these results emphasize that we must do more to stop people dying needlessly from heart disease caused by air pollution. Crucially, individual avoidance of polluted areas is not a solution to the problem. The government must put forward bold measures to make all areas safe and protect the population from harm,” he added.

Some researchers still argue that the study has many pitfalls. It includes the fact that gold is much different from the chemistry of the tiny particles present in pollution. Chief of the Society of Motor Manufacturers and Traders, Mike Hawes, said that the industry had invested billions in reducing emissions and had drastically reduced or banished pollutants such as particulates.