A study confirming a link between atmospheric pollution and heart-attack risk strengthens the EU case for tougher clean-air targets, experts say. Research in the BMJ looking at long-term data for 100,000 people in five European countries found evidence of harm, even at permitted concentrations. Experts stressed that the risk to an individual was still relatively small. And some argued the results were not conclusive as they did not take account of previous exposure to higher levels. Other factors, such as smoking or having high blood pressure, contribute more to a person’s risk of heart attack than pollution from traffic fumes and industry, they say. But repeated, long-term exposure to air pollution – living next to a busy road in a city, for example – does take its toll, the research, involving a collaboration of European universities and institutes, reveals.