A research has found that cycling is one of the biggest triggers of heart attacks.

In a new sliding scale of everyday risks that prove the ‘final straw’ in bringing on a heart attack, spending time in traffic – as a driver, cyclist or commuter – tops the list because of factors including stress and exposure to pollution.

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.

The study, which analyzed 36 pieces of research, is the first time the ‘final straw’ risk factors for triggering heart attacks – rather than underlying causes of heart disease – have been quantified. While some factors overlap, they were ranked by scientists in The Lancet medical journal online, after the proportion of total heart attacks caused by different triggers was calculated.

Traffic exposure was blamed for 7.4 per cent of heart attacks, followed by physical exertion with 6.2 per cent.

Overall air pollution triggered between 5 per cent and 7 per cent of heart attacks, while drinking alcohol or coffee accounted for 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, The Daily Mail reported.