Relationship between particulate matter and childhood asthma – basis of a future warning system for central Phoenix
Statistically significant correlations between increase of asthma attacks in children and elevated concentrations of particulate matter of diameter 10 microns and less (PM 10) were determined for metropolitan Phoenix, Arizona. Interpolated concentrations from a five-site network provided spatial distribution of PM 10 that was mapped onto census tracts with population health records. The case-crossover statistical method was applied to determine the relationship between PM 10 concentration and asthma attacks. For children ages 5–17, a significant relationship was discovered between the two, while children ages 0–4 exhibited virtually no relationship. The risk of adverse health effects was expressed as a function of the change from the 25th to 75th percentiles of mean level PM 10 (36 μg m −3). This increase in concentration was associated with a 12.6% (95% CI: 5.8%, 19.4%) increase in the log odds of asthma attacks among children ages 5–17. Neither gender nor other demographic variables were significant. The results are being used to develop an asthma early warning system for the study area.