February 24, 2011

Many Heart Attacks Triggered By Traffic Fumes

Air pollution is responsible for more heart attacks worldwide than cocaine, according to a new study published by Belgian researchers this week in the medical journal The Lancet.

Scientists at Hasselt University and the Catholic University of Leuven claim that traffic fumes and dirty air trigger more than eight times as many heart attacks than the illicit drug, Telegraph Medical Correspondent Stephen Adams wrote on Thursday.

Additionally, by looking at what they call "final straw" risk factors, the researchers declared that traffic exposure was the highest risk factor at 7.4%, according to a report in the Guardian on Wednesday.

The researchers used data from 36 different studies and calculated what is known as the population-attributable fraction or PAF of each trigger, according to Reuters Health and Science Correspondent Kate Kelland. "In other words," she added, the percentages given in the study represent "the proportion of total heart attacks estimated to have been caused by each trigger."

Physical exertion (6.2%) was second on the list, followed by alcohol (5%), coffee (5%), air pollutant particles known as PM10s (4.8%), negative emotions (3.9%), anger (3.1%) eating a heavy meal (2.7%), positive emotions (2.4%) and sexual activity (2.2%), the UK paper's website reported.

The authors discovered that "air pollution triggers 5-7% of heart attacks in the population" while "cocaine accounts for just 0.9% of all heart attacks," according to the Guardian article.

However, as Adams points out, those figures do not mean that using cocaine is safer than breathing polluted air.

"If an individual with heart disease takes cocaine, their chance of having a heart attack increases 26-fold," he wrote. "If a person with heart disease is exposed to heavy traffic fumes, their chance of having one increases by five percent."

However, "because most people are exposed to traffic fumes, and only a small number take cocaine, on a population-wide basis traffic pollution triggers more heart attacks, concluded the Belgian researchers," Adams added.

What it does mean, though, is that the quality of the air we breathe can nonetheless be putting us in danger.

"Our work shows that ever-present small risks might have considerable public health relevance," the authors wrote in their study, as quoted by Adams in his report. "Improvement of the air we breathe is a very relevant target to reduce the incidence of this disease in the general population."

"Of the triggers for heart attack studied, cocaine is the most likely to trigger an event in an individual, but traffic has the greatest population effect as more people are exposed to (it)," they added, according to Kelland's article. "PAFs give a measure of how much disease would be avoided if the risk was no longer present."


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