Key Point

People with diabetes, heart failure, COPD, and rheumatoid arthritis are at an increased risk of death when they are exposed to particulate air pollution.

SAN DIEGO—Particulate air pollution is a known danger to patients with respiratory conditions and heart disease. A recent study presented at the American Thoracic Society’s annual conference has found an association between particulate pollution and an increased risk of death in patients with COPD and other types of diseases, including diabetes, heart failure, and inflammatory diseases like rheumatoid arthritis.¹

Researchers studied 12-month averages of the concentration of particulate matter particles with a diameter of 10 mm (PM10) in the air of 34 cities between 1985 and 1999 and examined mortality rates in patients with the aforementioned conditions three years after hospital discharge. "In this study, we looked at air pollution and deaths within each city—we didn’t compare across cities," explained Joel Schwartz, PhD, Professor of Environmental Epidemiology at the Harvard School of Public Health in Boston.

TOXIC POLLUTION

The researchers found that for each 10-µg/m3 increase in PM10 over two years, the relative risk of dying increased by 32% in people with diabetes, 28% in those with COPD, 27% in congestive heart failure patients, and 22% in rheumatoid arthritis or lupus patients. "The study significantly strengthens evidence that breathing in particulate matter is associated with dying sooner," commented Dr. Schwartz.

Previous studies have shown links between air pollution and conditions such as respiratory problems and cancer. However, this is the first study to follow people who have specific diseases and exposure to particulate matter. Moreover, the study validates the findings of previous studies showing that long-term exposure to air pollution is associated with shortened survival in the general population.

>"We looked at risk of death in the first three years after patients were discharged from the hospital and saw that the risk increased in the first couple of years," explained Dr. Schwartz. Citing the public health impact, he continued, "That means if we can lower air pollution levels, people will start living longer right away—we don’t have to wait many years to see health improvements." Dr. Schwartz acknowledged that other studies have not shown this.

Dr. Schwartz believes that cumulative exposure to particulate air pollution over a year or longer increased the health risk beyond that for acute exposure. "There is no safe level of particulate air pollution, so we need to get the levels as low as reasonably possible," he concluded.

—Tamara Gibb

Reference
1. Zanobetti A, Schwartz J. Multi-city survival analysis in susceptible populations. Presented at: annual meeting of the American Thoracic Society; May 22, 2006; San Diego, Calif.

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