Air pollution may double the risk that an elderly person will be hospitalized for pneumonia, according to a new study.
"We have shown that air pollution exerts a strong effect on hospital admissions for pneumonia," Michael Jerrett, of the University of California, Berkeley, who was involved in the study, noted in an interview with Reuters Health.
About 600,000 people are hospitalized for pneumonia in the United States each year. Pneumonia is the leading cause of death in the elderly.
The study—led by researchers at McMaster University in Canada and reported in the American Journal of Respiratory and Critical Care Medicine—looked at health data from 345 people who had been hospitalized for pneumonia within a two-year period. All of them were 65 or older and lived in Hamilton, Ontario.
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 hospitalization for pneumonia. They merged this information with the participants' health data.
The researchers found that people living in the parts of the city with the highest levels of fine particulates and nitrogen dioxide had more than twice the chance of being hospitalized with pneumonia as people living in cleaner parts of the city. The results held up after the researchers controlled for other risk factors for pneumonia, such as smoking.
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. This increases the risk of lung infections such as influenza and pneumonia.
"The best way to deal with this type of air pollution is to clean up the source and reduce it in areas where it is high," said Jerrett, who pointed out that one in three Americans lives in places that regularly exceed federal air pollution standards.
"This is a serious public health problem that needs to be dealt with at the societal level," he said.
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