Coarse Particles Worsen Cough and Phlegm in Kids with Asthma
Even low concentrations of PM air pollution may cause symptoms of respiratory distress in children with asthma, according to a new study in Spokane, Washington.
A panel of sixteen adults and nine children with asthma kept daily diaries of their respiratory symptoms over many months. Air pollution data on various size fractions of particulate matter were collected in a city with diverse source of PM, including motor vehicles, woodstoves, agricultural burning, responded road dust, and dust storms.
In children, a strong association between cough and PM2.5 (fine particles), PM1, PM10 and PM10-2.5 (coarse particles) was found. Stronger associations with cough were reported for coarse particles than for fine. Increased phlegm and runny nose were associated with PM10 and PM10-2.5. However, no association was found between any measure of PM and respiratory symptoms in the adults.
The results suggest that children are more sensitive than adults to the effects of increased levels of PM air pollution, or that the ambient air quality monitor was more representative of children’s exposures, because they spend more time outdoors than adults.
Researchers concluded: “The association between asthma aggravation and coarse particles adds to the growing literature suggesting an association between this particle size and asthma aggravation. Such a finding is physiologically feasible since particles in this size range are known to deposit in the large bronchial airways.” Lower respiratory symptoms were more strongly associated with increases in fine particles.
Mar TF, Larson TV, Stier RA, Claiborn C, Koenig JQ. An analysis of the association between respiratory symptoms in subjects with asthma and daily air pollution in Spokane, Washington. Inhalation Toxicology 2004; 16:809-815.
The National Library of Medicine [www.ncbi.nlm.nih.gov] offers the abstract online.
