For the study, which followed a group of asthmatic children in Baltimore, researchers from the Center for Childhood Asthma in the Urban Environment followed 150 asthmatic children, ages 2 to 6, for six months. Environmental monitoring equipment was used to measure the air in the child's bedroom over three-day intervals. Air measurements were taken at the beginning of the study, after three months and again after six months.

"We found that substantial increases in asthma symptoms were associated both with higher indoor concentrations of fine particles and with higher indoor concentrations of coarse particles," said Meredith C. McCormack, MD, MHS, lead author of the study.

For every 10 micrograms per cubic meter of air (ug/m3) increase in indoor coarse particle concentration, there was a 6 percent increase in the number of days of cough, wheeze, or chest tightness, after adjusting for a number of factors.

For every 10 ug/m3 increase in fine particles measured indoors, there was a 7 percent increase in days of wheezing severe enough to limit speech and after adjusting for various factors, a 4 percent increase in days on which rescue medication was needed. In many cases, the level of indoor fine particle pollution measured was twice as high as the accepted standard for outdoor pollution established by the Environmental Protection Agency.

"Children spend nearly 80 percent of their time indoors, which makes understanding the effects of indoor air very important," said co-author Gregory B. Diette.

EPA regulates outdoor levels of fine particle pollution, but does not have a standard for coars particle pollution. The study was published in February 2009 edition of the journal Environmental Health Perspectives.

Article Courtesy of Scarlett, Tom. "Study Links Indoor Air Pollution, Asthma." Indoor Environment Connections Volume 10, Issue 5 – March 2009.