TINY particles emitted by diesel exhaust fumes can raise the risk of heart attacks, according to new research.

Scientists from Edinburgh University discovered ultra-fine particles produced when diesel burns are harmful to blood vessels and can increase the chances of blood clots forming in arteries, leading to a heart attack or stroke.

The research sheds further light on the risks of traffic fumes after another study from Italy warned high levels of exposure to tiny particles in emissions can dramatically raise the risk of deep-vein thrombosis.

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Glasgow has a long-standing problem with air pollution and was recently named as one of three areas in the UK – alongside Greater London and north-east Scotland – which were expected to fail European limits for nitrogen dioxide emissions.

The British Heart Foundation said the research confirmed people with heart disease should not spend long periods of time outdoors in areas where there are high levels of traffic pollution.

The researchers compared the carbon monoxide and nitrogen dioxide found in diesel fumes to the ultra-fine particles from exhausts and found it was the chemicals – which are less than one-millionth of a metre wide – that interfered with the way the blood vessels control blood-flow.

Dr Mark Miller, of Edinburgh University’s Centre for Cardiovascular Science, said: “While many people tend to think of the effects of air pollution in terms of damage to the lungs, there is strong evidence it has an impact on the heart and blood vessels as well.

“Our research shows that while both gases and particles can affect our blood pressure, it is actually the miniscule chemical particles emitted by car exhausts that are really harmful. These particles produce highly reactive molecules called free radicals that can injure our blood vessels and lead to vascular disease. We are now investigating which of the chemicals carried by these particles cause these harmful actions, so we can try and remove these chemicals, and prevent the health effects of vehicle emissions.”

A report last month by the Department for the Environment, Food and Rural Affairs showed Glasgow and north-east Scotland were breaching European Union safe levels for nitrogen dioxide air pollution.

The EU annual average target for nitrogen dioxide levels is 40 micrograms per cubic metre but two years ago Glasgow’s Hope Street, a main bus corridor, recorded an annual average of 82 micrograms, while St John’s Road in Edinburgh averaged 75 micrograms a year.

The study, which is published in the European Heart Journal, was funded by the British Heart Foundation, which said there may be an argument for taking chemicals out of fuel to reduce the initial risk.

Its associate medical director, Professor Jeremy Pearson, said: “We’ve known for a long time air pollution is a major heart health issue and that’s why we’re funding this team in Edinburgh to continue their vital research.

“Their findings suggest lives could be saved by cutting these harmful nanoparticles out of exhausts – perhaps by taking them out of the fuel, or making manufacturers add gadgets to their vehicles that can trap particles before they escape. The best approach isn’t clear yet.

“For now our advice remains the same – people with heart disease should avoid spending long periods outside in areas where traffic pollution is likely to be high, such as on or near busy roads.”