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(Ivanhoe Newswire) -- Older adults with long-term exposure to higher levels of pollution are at greater risk for hospitalization for pneumonia.
"Our study found that among older individuals, long-term exposure to traffic pollution independently increased their risk of hospitalization for pneumonia," principal investigator, Mark Loeb, M.D., of McMaster University, Ontario, Canada, was quoted as saying.
Pneumonia is a leading cause of sickness and death among older adults, and rates of hospitalizations for pneumonia among patients 65 and older have increased in recent years. In addition to road traffic pollution, Hamilton, Ontario, has an industrial steel-making complex in the north end of the city that creates a large exposure zone for residents.
The researchers recruited 365 older adults from Hamilton who had been hospitalized with radiologically confirmed pneumonia in one of Hamilton's four emergency departments between 2003 and 2005. Control subjects from the same catchment areas as the patients were enrolled contemporaneously. Researchers examined their exposure to nitrogen dioxide, sulfur dioxide, and fine particulate matter using data from air-quality monitoring stations and land use regression models.
The researchers found that long-term (more than 12 months) exposure to nitrogen dioxide and fine particulate matter were associated with more than double the risk of hospitalization for pneumonia. Exposure to sulfur dioxide was not associated with increased risk of hospitalization.
"We postulate that long-term exposure to air pollution may have increased individuals' susceptibility to pneumonia by interfering with innate immune defenses designed to protect the lung from pathogens. This may have included epithelial cell damage, reductions in bronchial macrophages, or reductions in natural killer cells," said Dr. Loeb.
"Given the large population exposure to ambient air pollution, the results of this study highlight the important health impact that long-term exposure to ambient air pollution can have on respiratory infections," wrote Dr. Loeb. "It also emphasizes the need to monitor emissions from vehicles, given that ground level NO2 is derived predominantly from traffic."
SOURCE: American Journal of Respiratory and Critical Care Medicine, January 1, 2010
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