London: Cycling has always been touted as being good for health, but now a study has found that it is actually one of the biggest triggers of heart attacks.
The study, which analysed 36 pieces of research on everyday risks, proves that the "final straw" in bringing on a heart attack is spending time in traffic as a driver, cyclist or commuter.
But of the three, 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 percent of heart attacks, followed by physical exertion with 6.2 percent, while air pollution triggered between 5 percent and 7 percent of heart attacks, and drinking alcohol or coffee accounted for 5 percent.
Other risk factors included negative emotions (3.9 percent), anger (3.1 percent), eating a heavy meal (2.7 percent), positive emotions (2.4 percent) and sexual activity (2.2 percent).
Cocaine was to blame for 0.9 percent of heart attacks, but this was because of limited exposure to the drug among the population.
According to the study, led by Dr Tim Nawrot, from Hasselt University in Belgium, on an individual basis, taking cocaine was shown to raise a person``s risk of having a heart attack 23-fold.
In comparison, air pollution led to a 5 percent extra risk, but since far more people are exposed to traffic fumes and factory emissions than cocaine, air quality is a far more important population-wide threat.
Professor David Spiegelhalter, a risk expert from Cambridge University, said it was difficult to "disentangle" the risk factors in the study for certain situations, such as driving or cycling to work in heavy traffic.
"A lot of other factors are contributing to the overall risk; air pollution, stress, physical exertion, even anger which is another well-known trigger for a heart attack. It``s a complex mix," the Daily Mail quoted him as saying.
Judy O``Sullivan, senior cardiac nurse at the British Heart Foundation, said the benefits of exercising outdoors outweighed the risks from air pollution for most individuals, and urged people not to be put off running, walking or cycling in towns and cities.