Daily Asthma Severity in Relation to Personal Ozone Exposure and Outdoor Fungal Spores

摘要

Epidemiologic investigations of ambient ozone (O_3) effects on daily asthma status have not used personal O_3 exposures and have often lacked well-characterized allergen exposures. To address this, we studied 12 asthmatic subjects aged 9 to 16 yr, who recorded daily asthma symptoms (functional levels 0 to 5) and as-needed inhaler use during September and October 1993 in San Diego, California. Outdoor aeroallergens, O_3, and fine particle concentrations were measured at a central outdoor site, and personal 12-h daytime exposures to O_3 were measured daily. Personal O_3 differed greatly between subjects and was 27% of mean outdoor O_3. In random-effects autoregression models controlling for weekend days and fungal spores, personal O_3 was associated with asthma severity: for a 90th percen-tile increase in O_3 (25 ppb), symptom scores increased by 25% (95% CI: 0 to 49%) and inhaler use increased by 26% (95% CI: 3 to 48%) over their averages. Outdoor 12-h O_3, but not 1-h maximum O_3, was associated with inhaler use (p < 0.03). Fungal spores were significantly associated with symptoms (scores increased by 0.1 to 0.3/1,000 spores/m~3) and inhaler use (0.1 to 0.4 puffs/1,000 spores/ m~3) across speciated groups. Pollen and fine particles (low levels) were not associated with any outcomes. These findings illustrate that the epidemiologic importance of O_3 and allergenic cofactors can be underestimated by failure to account for personal O_3 and fungal exposures.