Long-term exposure to air pollution has been linked to a sharp increase in heart attacks and angina cases, according to research in five European Union countries that was conducted over more than a decade.
Excluding illness, poverty and smoking, researchers found that an increase of just a fifth in the levels of the smallest pollution particles, caused by engine fumes and coal smoke, cause heart attack numbers to jump by 13 per cent.
However, the research, published today by the British Medical Journal, warned that European Union permitted levels are not strict enough. The number of cases rises by 18 per cent when pollution jumps by a fifth, but still stays below limits permitted by Brussels.
In the EU, the current annual pollution limit, known as PM2.5, is set at 25 micrograms (one-millionth of a gram) per cubic metre of air. This limit is more than double the figure permitted in the United States.
The research by an international team of experts was led by the University of Utrecht in the Netherlands, which studied over 100,000 people with no prior history of heart disease from 1997 to 2007. The subjects came from Finland, Sweden, Denmark, Germany, and Italy. Over 5,000 people suffered heart attacks or problems during the years when they were surveyed by the medical team.
Swedish residents faced the lowest average pollution figures, 7.3 micrograms per microlitre, but people living Northern Italy had to cope with rates averaging 31mg.
The latest World Health Organisation Global Burden of Disease report estimated that air pollution causes 3.1m deaths a year and a fifth of all of the healthy years lost by people throughout the world to ischaemic heart disease.
Several past studies have linked pollution to mortality, particularly deaths from heart attacks – though the evidence that it causes or increases acute myocardial infarction and unstable angina cases “is less consistent and requires further investigations”, they note.
Dublin-based Prof Luke Clancy said the latest figures show there are “no safe” levels for air pollution, though he added that a zero limit could not be achieved because compromises will always be necessary due to economic priorities.
“It is now accepted that there is no zero limit. All pollution has a contribution to make towards mortality figures,” he told The Irish Times, adding, however, that the ban on smoky coal in Dublin brought about an 80 per cent drop in pollution “that never came back”.
Prof Jon Ayres of the University of Birmingham said the results “have been awaited eagerly for some time” because the same methodology was used across all five countries and the results were “remarkably consistent”.
The five micrograms rise in PM2.5 required to increase heart attacks by 13 per cent is equal to the difference between “living in a less polluted city such as Edinburgh compared to a bigger one like Glasgow”, Dr Jeremy Langrish from the University of Edinburgh said.
However, he cautioned that “the absolute risk is quite small”, since 450 people a year out of the 100,000 would be expected to report heart problems of some nature, “so a 13 per cent increase would be an extra 59 cases a year”.
Calling for further falls in permitted pollution levels, the British Heart Foundation said research carried out Edinburgh over the last five years has clearly shown how exhaust fumes affect the operation of the heart and blood vessels.
To read the full study: Long term exposure to ambient air pollution and incidence of acute coronary events: prospective cohort study and meta-analysis in 11 European cohorts from the ESCAPE Project www.bmj.com