Hospital admissions for respiratory conditions in children and outdoor air pollution in Southwest Milan, Italy

Aim: To evaluate whether a relationship exists in hospital admissions for respiratory conditions in children with outdoor pollution in the Southwest Milan, Italy. Methods: Daily count of hospital admissions for asthma, upper or lower respiratory diseases (LRD) occurred among children aged < 14 years at the San Paolo Hospital during 2007-2008 was recorded. Pollutants included the particular matter of < 10 mu m diameter, ozone, carbon monoxide (CO) and nitrogen dioxide (NO(2)), reported on the same day of admission and 1 up to 5 days before admission. The moving weekly average (MWA) was also considered. Results: Total respiratory admissions were associated with the same day level of CO (30.6% increase per 1 mg/m3 increase, 95% confidence interval, 3.9-69.9%) and with the MWA of NO(2) (9.0% increase per 10 mu g/m3 increase, 1.2-16.8%). The effect of CO was stronger on upper respiratory diseases (URD) (lag 0, 21.3% increase, 6.4-38.3%). The effect of NO(2) was stronger on LRD (MWA, 5.3% increase, 0.9-10.2%). Multipollutant models confirmed the role of CO on URD and that of NO(2) on LRD. Conclusion: Carbon monoxide and nitrogen dioxide may be associated with emergency hospital admissions for respiratory conditions among children in Southwest Milan.