London, Feb 19 : Breathing car exhaust fumes can trigger heart disease and increase the risk of strokes, say researchers.
The study found that the chemicals released during the burning of petrol and other fuels weakened the heart's ability to pump effectively and can lead to irregular heartbeats.
Dr John Incardona, a biologist and toxicologist at the West Coast Centre for Oceans and Human Health, in Seattle, said that the research suggests that millions of people living in large cities are effectively "breathing an aerosolised oil spill".
In the study, the researchers exposed zebrafish embryos to the most abundant PAHs found in oil and petrol, and found that smaller PAHs caused the developing heart to beat more weakly and with an abnormal rhythm. A failure to pump properly caused fluid build-up.
Polycyclic Aromatic Hydrocarbons (PAHs) are compounds released during the combustion of fossil fuels.
"The available data suggests that these PAHs are present in burning oil in levels high enough to result in pharmacologically active levels in the human blood stream," the Telegraph quoted Incardona, as saying.
"Once in the bloodstream, they are likely to be toxic to the human heart, and should be considered prime suspects for the health effects of urban air. In essence, people in big cities are breathing an aerosolized oil spill.
"A physician who knowingly gave an aerosolised particle toxin to a patient with coronary artery disease or congestive heart failure would probably be sued for malpractice. But the air in our cities is doing just that to millions every day unknowingly," he added.
Dr Incardona added: "It turns out that fish hearts even in the embryo function more like human hearts than even mice or rats, the usual test animals in human health studies.
"Every time your burn something you generate PAHs. The smaller PAHs have been largely ignored because they are not carcinogenic.
"Here is this relative mystery of how air pollution could possibly start a heart arrhythmia in humans. This is a very simple hypothesis and I think these compounds need to be looked at as a source of cardiovascular impacts of air pollution."
The study was presented at the Annual Association for the Advancement of Science (AAAS) conference in Boston.