Scots scientists say wearing a mask in traffic reduces heart attack risk

Published on Thursday 12 March 2009 20:55

WEARING a face mask can reduce the risk of heart disease from traffic fumes, Scots scientists have shown.

Researchers discovered that pollution from car exhausts caused arteries to stiffen, resulting in higher blood pressure and reduced blood flow to the heart.

Using China as a testing ground scientists from the University of Edinburgh found wearing a face mask reduced the impact of fumes by up to 98 per cent in Beijing.

A dozen non-smoking young men cycled on exercise bikes while breathing air that had been contaminated with smoke from a diesel engine.

After just an hour their arteries stiffened. The blood vessels in their wrists temporarily lost the ability to expand and contract, resulting in higher blood pressure and reduced flow to the heart.

Dr Nicholas Mills, from the Centre for Cardiovascular Science at the University of Edinburgh, said: "Stiff arteries can result in raised blood pressure and reduced blood flow in the heart. Arterial stiffness plays an important role in hypertension.

"Acute exposure to diesel exhaust is associated with an immediate and transient increase in arterial stiffness.

"This may, in part, explain the increased risk for cardiovascular disease associated with air pollution exposure."

Masks helped to alleviate the problem, but some were more effective than others.

Those used to protect workers from dust in industrial environments were considerably more successful at blocking the harmful fumes than those usually marketed towards cyclists and pedestrians, or handkerchiefs or surgical masks.

It was the first time face masks had ever been tested for their efficacy, even though they are commonly worn in particularly polluted cities such as Beijing, and by cyclists around the world.

"There was no evidence before we carried out this research that they did any good," said Dr Mills. "So this was a novel study.

"We went to Beijing to do the research because it is one of the most polluted cities in the world. The most effective face mask could reduce your blood pressure even over a short period of time."

Dr Mills added: "The most effective turned out to be a cheap and simple face mask designed to reduce occupational exposure to dust."

However, he said these masks were not designed for high performance exercise, so they might not be suitable for cyclists.

Dr Mills said the research suggested masks could be helpful in the most smog-covered cities in the world, but said it was still not clear how beneficial they would be in less polluted places, such as Scotland.

Meanwhile, a German study has shown that people who have had a heart attack are likely to have been in traffic shortly before their symptoms began.

Three times as many patients had been in traffic up to an hour before the onset of their heart attack, as those who had not.

Most commonly, patients had been driving a car, but others had been exposed to traffic by using public transport, or riding a bicycle.

Annette Peters, from the Institute of Epidemiology, Helmholtz Zentrum Muchen in Germany, said: "Driving or riding in heavy traffic poses an additional risk of a heart attack in persons already at elevated risk.

"In this study, underlying vulnerable coronary artery disease increased the risk of having a heart attack after driving in traffic."

She said one reason for the increased risk of heart attack could have been the exhaust from other cars, but added that stress could also play a part.