Airborne Particle Counts, Dust Endotoxin and Activity Limitation in Inner-City Asthmatic Children

Asthma prevalence has risen steadily in the developed world in recent decades. In the United States the asthma epidemic has disproportionately affected minority and low income groups with children of color in urban environments being the most significantly affected. While causal links between environmental exposures and the development of asthma have not been established, many environmental exacerbants of the disease are well known. Exposure to these environmental contaminants in the residential environment is of particular concern for children due to the amount of time that they spend indoors at home. This research involved an evaluation of the relationship between the limitation of activity in 74 asthmatic children in inner-city Philadelphia and both airborne particulate count size fractions and dust endotoxin concentrations. A community based participatory model was utilized in which outreach workers performed home inspections, delivered tailored asthma interventions, administered surveys, and collected environmental samples. The Children's Health Survey for Asthma was used to measure activity limitation. Particulate samples were collected with handheld 6 channel particle counters. Dust endotoxin was collected on 25mm polycarbonate filters in endotoxin free cassettes. Statistical analysis indicated a positive significant association between the concentration of particles smaller than 0.3 microns and activity limitation, indicating that these particles adversely affected asthmatic children in our study. The 0.5 – 1.0 micron fraction was also significantly associated with activity limitation, however these particulates appeared to be protective. Endotoxin was not observed to be associated with activity limitation, however associations were observed between dust endotoxin and several particulate size fractions.