Objectives: Health effects of ozone (O3) have been observed in numerous studies. However, analyses for more cause-specific morbidity or mortality outcomes have rarely been performed. Therefore, we determined the short-term associations of ozone with cause-specific cardiorespiratory mortality and morbidity by age groups.
Methods: Daily levels of O3 were measured at a background measurement station in 1998-2004 in Helsinki, Finland. All analyses were a priori restricted to the warm season. Among the elderly (≥65 years) and adults (15-64), we studied daily cause-specific cardiorespiratory mortality and hospital admissions. We also analyzed data on associations between O3 and asthma emergency room visits among children (<15 years). We adjusted all models for PM2.5, and used Poisson regression for the analyses.
Results: We found a positive association between O3 and asthma-COPD admissions among the elderly (9.6%; 95% CI, 2.0 – 17.8, at 0-day lag for 25µg/m3 increase in O3). We found also consistent associations between O3 and asthma emergency room visits among children (e.g. 12.6%; 0.8 – 25.1, 0-day lag). There was a suggestion of an association between O3 and arrhythmia admissions among the elderly (6.4%; 0.63 – 12.5, 1-day lag), which was slightly confounded by PM2.5.
Conclusions: We found positive associations for ambient ozone with asthma visits among children and with pooled asthma-COPD admissions among the elderly. The evidence of positive association between ozone and cardiovascular health was weaker.