Cycling can lead to heart attacks
The study, which analysed 36 pieces of research, has revealed that the "final straw" in bringing on a heart attack is spending time in traffic as a driver, cyclist or commuter, `The Lancet` journal reported.
But of these, cyclists are in greatest danger because they are more heavily exposed to pollution and are subjecting themselves to another major heart attack trigger, exercise.
Traffic exposure was blamed for 7.4 per cent of heart attacks, followed by physical exertion with 6.2 per cent Over -all air pollution triggered between 5 per cent and 7 per cent of heart attacks, while drinking alcohol accounted 5 per cent.
Other risk factors included negative emotions (3.9 per cent), anger (3.1 per cent), eating a heavy meal (2.7 per cent), positive emotions (2.4 per cent) and sexual activity (2.2 per cent)
Cocaine was to blame for 0.9 per cent of heart attacks, but this was because of limited exposure to the drug among the population.
On an individual basis, taking cocaine was shown to raise a person`s risk of having a heart attack 23-fold, according to the study, led by Dr Tim Nawrot, from Hasselt University in Belgium.