A new investigation into air pollution and heart attack has found a raised risk from all major pollutants except ozone.
For over 50 years, scientists have suspected that high air pollution can impact on health, and many previous studies have shown links between air pollution levels and hospital admissions or death rates.
But the link between air pollution and short-term heart attack risk remains controversial, say Dr Hazrije Mustafic of the University Paris Descartes, France, and colleagues in the Journal of the American Medical Association today.
They set out to assess the heart attack risk from short-term (up to a week) exposure to ozone, carbon monoxide, nitrogen dioxide, sulphur dioxide, and small-particle matter. Figures were taken from 34 studies.
"All the main air pollutants, with the exception of ozone, were significantly associated with an increase in heart attack risk," report the authors.
They highlight several possible reasons for the links. "The first potential mechanism is inflammation," they write. "Studies have shown that levels of inflammatory markers such as C-reactive protein are higher as a result of exposure to air pollution."
Alternatively, high levels of air pollution may trigger an increased heart rate, or thirdly, heart risk may be raised by an increase in blood viscosity due to air pollution.
The authors state that an improvement in air quality could have a significant effect on public health. But they conclude: "Further research is needed to determine whether effective interventions that improve air quality are associated with a decreased incidence of heart attack."
Main Air Pollutants and Myocardial Infarction A Systematic Review and Meta-analysis. Mustafic, H. et al. The Journal of the American Medical Association February 15 2012 Volume 307 Number 7 pp. 713-21.
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