Car fumes raise heart attack risk
24 Sep BBC
Breathing in heavy traffic fumes can trigger a heart attack, say UK
experts.
Heart attack risk is raised for about six hourws post-exposure and
goes down again after that, researchers found. They say in the British
Medical Journal that pollution probably hastens rather than directly
cause attacks. But repeated exposure is still bad for health, they say,
substantially shortening life expectancy, and so the advice to people
remains the same - avoid as far as is possible. Prof Jeremy Pearson,
associate medical director at the British Heart Foundation, which
co-funded the study, said: "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."
Early peak The research looked at the medical records of almost
80,000 heart attack patients in England and Wales, cross-referencing
these details with air pollution data.
This enabled the investigators to plot hourly levels of air pollution
(PM10, ozone, CO, NO2, and SO2) against onset of heart attack symptoms
and see if there was any link. Higher levels of air pollution did appear
to be linked with onset of a heart attack lasting for six hours after
exposure.
After this time frame, risk went back down again.
Krishnan Bhaskaran from the London School of Hygiene and Tropical
Medicine, who led the research, said the findings suggested that
pollution was not a major contributing factor to heart attacks.
For example, being exposed to a spell of medium-level rather than
low-level pollution would raise heart attack risk by 5%, by his
calculations. "If anything, it looks like it brings heart attack forward
by a few hours. These are cardiac events that probably would have
happened anyway." |