Airborne particulate matter from primarily geologic, non-industrial sources at levels below National Ambient Air Quality Standards is associated with outpatient visits for asthma and quick-relief medication prescriptions among children less than 20 years

In Anchorage, Alaska, particulates with aerodynamic diameter ⩽10 μm (PM10) arise primarily from natural, geologic sources, and particulates with aerodynamic diameter ⩽2.5 μm (PM2.5) arise primarily from automobile emissions. The current study used a population-based time-series analysis design to evaluate the effects of daily and weekly PM10 and PM2.5 on respiratory health outcomes among children <20 years of age residing in Anchorage enrolled in Medicaid. All generated estimating equations models were adjusted for season, year, weekends, temperature, wind speed, and precipitation. Relative to the days with PM10 mass concentration ⩽13 μg/m3, a significant 9.3% increase (RR: 1.093, 95% CI: 1.004–1.191) in the rate of outpatient visits for asthma occurred during days with PM10 of 20–33 μg/m3. No further dose–response occurred for days with PM10 ⩾34 μg/m3. A significant 18.1% increase (RR: 1.181, 95% CI: 1.010–1.381) in the rate of quick-relief medication prescriptions occurred during days with PM10 of 34–60 μg/m3, and a 28.8% increase (RR: 1.288, 95% CI: 1.026–1.619) occurred during days with PM10⩾61 μg/m3. Similar results for outpatient asthma visits and quick-relief medication occurred in weekly models. There were no significant associations with PM2.5 in either daily or weekly models. These subtle but statistically significant associations suggest that non-industrial, geologic sources of PM10 may have measurable health effects at levels below current national standards.