The U.S. Environmental Protection Agency has proposed tightening the national air quality standards for microscopic particles that pollute the air and pose a serious threat to public health.
Fine particles are defined as being no larger than 2.5 micrometers in diameter or smaller -- less than 1/30th the diameter of a human hair. The tiny dust particles come from a variety of sources, including coal-burning power plants, factories and automobile exhaust.
A study in the Journal of the American Medical Association reports that even a small increase in exposure to fine particles increases the risk of developing heart and lung disease.
The study followed 11.5 million people enrolled in Medicare, a government health program for older and disabled Americans. Lead author Francesca Dominici, with Johns Hopkins University's Bloomberg School of Public Health, says the study links health records with day-to-day air pollution and weather data for 204 large urban centers across the United States.
"For [all] these counties in 2002, there were 1.4 million hospitalizations for cardiovascular and respiratory disease," she says. "So for each increase in 10 units [micrograms per cubic meter] in PM 2.5 [fine particles] we see 11,000 extra hospitalizations."
The oldest participants experienced a higher risk of heart and lung complications associated with days of high particle pollution. Dominici says the study establishes a framework to track these risks nationwide as more data become available.
"We can make our methodology available on the web," she says. "Other countries around the world that have started to monitor air pollution data can use our methodology to apply to their own data."
Dominici says researchers at the Bloomberg School of Public Health have already begun collaboration on similar projects in Europe and Canada. Health advocates in the United States are using the data to make the case for tighter air pollution standards than those recently proposed by the U.S. Environmental Protection Agency.