Dirty air raises pneumonia risk

Air pollution may double the risk of an elderly person being hospitalised for pneumonia.

Pneumonia is the leading cause of death in the elderly. Air pollution exerts a strong effect on hospital admissions for pneumonia. About 600,000 people are hospitalised for pneumonia in the United States each year. Little is known about how air pollution contributes to an increased risk of pneumonia. Animal studies have shown that pollutants such as nitrogen dioxide impair the oxygen exchange areas of the lung, which increases the risk of lung infections such as influenza and pneumonia.

Researchers looked at health data from 345 people who had been hospitalised for pneumonia within a two-year period. All of them were 65 years or older and lived in Hamilton, Canada. Hamilton is home to a large industrial steel-making complex. Residents living near the complex are exposed to high levels of tiny, floating particles known as particulate matter. The researchers calculated annual average pollution levels of fine particulate matter and nitrogen dioxide, a pollutant primarily associated with traffic, near the participants' homes for the two years prior to hospitalisation for pneumonia. They correlated this information with the participants' health data.

It was found that people living in the parts of the city with the highest levels of fine particulate matter and nitrogen dioxide had more than twice the chance of being hospitalised with pneumonia as people living in cleaner parts of the city. The results held up after the researchers factored in the effect of other risk factors for pneumonia, such as smoking.

The researchers suggest that this is a serious public health problem that needs to be dealt with at the societal level to reduce air pollution.

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