21.9.2011 Traffic fumes can trigger heart attacks
A new report published in the British Medical Journal concludes that some traffic emissions can significantly increase the risk of a heart attack for up to six hours.
The report identifies particulate matter (PM10) and nitrogen dioxide (NOx) as being the most harmful pollutants, both which are expelled by vehicles and contribute significantly to urban air pollution.
The study does say that the risk of exposure to these pollutants actually triggering a heart attack is small – a 1.3% risk increase up to 6 hours after exposure. The author's predict that breathing in enough of these substances can bring forward a heart attack by several hours, if it was destined to happen anyway. Scientists call this the 'harvesting' effect of pollution.
However, the number of heart attacks was seen to fall to an average or lower level after the 6 hour period.
At the London School of Hygiene and Tropical Medicine, 79,288 heart attacks from 15 different urban areas in the UK between 2003 and 2006 were inspected. This data was compared to pollution statistics at the time and location of each heart attack, supplied by the UK National Air Quality Archive.
Data was supplied about levels of carbon monoxide, sulphur dioxide and ozone, as well as the mentioned PM10 and NOx. The report predicts that higher levels of traffic-associated pollutants, in particular PM10 and NOx, will be followed by increased risk of a heart attack up to 6 hours later.
There are estimates that traffic pollution is responsible for 4,200 premature deaths a year in London alone, and 29,000 annually across the UK. The government has been criticised for not effectively tackling urban air pollution and its damaging effects.
There are strict European Union targets to tackle air pollution, and the UK will face significant penalties if these are not achieved. This study is said to have reiterated the urgency with which the government must tackle air pollution in order to comply with these EU limits.
Associate medical director of the British Heart Foundation, Professor Jeremy Pearson commented, "This large-scale study shows conclusively that your risk of having a heart attack goes up temporarily, for around six hours, after breathing in higher levels of vehicle exhaust."
"We know that pollution can have a major effect on your heart health, possibly because it can 'thicken' the blood to make it more likely to clot, putting you at higher risk of a heart attack. Our advice to patients remains the same – if you've been diagnosed with heart disease, try to avoid spending long periods outside in areas where there are likely to be high traffic pollution levels, such as on or near busy roads."
There is a significant opportunity for electric and some hybrid vehicles to play a vital role in reducing urban air pollution. It is therefore in the interest of our government to inventivise and encourage the uptake of alternatively fuelled vehicles, especially within urban areas.
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