Tuesday, April 5, 2011

Danger is in the air: Cycling biggest trigger of heart attack

LONDON: Doctors have for long said that cycling is good for health. But, now a new study has claimed it is literally one of the biggest triggers of 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 report

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% of heart attacks, followed by physical exertion with 6.2%. Over-all air pollution triggered between 5% and 7% of heart attacks, while drinking alcohol accounted 5%.

Other risk factors included negative emotions (3.9%), anger (3.1%), eating a heavy meal (2.7%), positive emotions (2.4%) and sexual activity (2.2%). Cocaine was to blame for 0.9% 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. In comparison, air pollution led to a 5% 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.

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."

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