Respiratory diseases in children and outdoor air pollution in Sao Paulo, Brazil: a time series analysis

Objectives-To investigate the short term effects of air pollution on the respiratory morbidity of children living in Sao Paulo, Brazil, one of the largest cities in the developing world. Methods-Daily counts of hospital admissions due to respiratory diseases along with daily levels of meteorological variables and air pollutants (PM10, SO2, NO2, O-3, and CO) were analysed with Poisson regression. Final models were adjusted for the effects of time trends, seasonal patterns, weekdays, holidays, meteorological factors, and serial correlation. Results-Daily admissions of children to hospital for total respiratory disease and pneumonia showed significant increases associated with O-3 (5-8%), NO2 (9%), and with PM10 (9%) (results are for an increase from the 10th to the 90th percentile of pollution measurements). Consistently, effects for pneumonia were greater than for all respiratory diseases combined. Also, effects on infants (children <1 year old) presented higher estimates. Similar associations were found for asthma admissions. Point estimates for most pollutants were higher for asthma than for other diagnosed admissions. However, these associations were not significant. Conclusions-These results agree with the limited publications on this subject but indicate a rather smaller magnitude of effects. Nevertheless, given the present concentrations of air pollution in Sao Paulo and the large population potentially exposed attention should be directed to minimise such effects.