Impact of urban air pollution on influenza

In Sao Paulo city the main source of air pollution is its automotive fleet running on a gasoline-ethanol mixture. The aim of the study was to assess the effect of pollutants on Influenza .We obtained from 2001 to 2003 daily records: of attendances at Sao Paulo Hospital Emergency Unit (SPHEU) with ICD 10th J10-J11, of levels of PM10, NO2, SO2, CO, and O3, of temperature and humidity. GLM Poisson regression was adopted using daily number of Influenza visits as dependent variables. Long-term trend was controlled by a semi parametric function. Linear terms were used for temperature and humidity. Effects were presented as percentage increase and 95% CI in influenza visits due to inter quartile range increases in air pollutants daily levels. During the study period, 137,530 visits for respiratory diseases occurred in the SPHEU, of which 12% were for influenza. In terms of age groups, emergency visits of children and younger than 13 years of age were the most frequent, followed by the groups 40 to 65 years, 30 to 39 years, older than 65 years and adolescents from 13 to 19 years old. PM10 presented effects at lag zero on daily visits due to influenza among young people 13 to 19 years and with over 65 years. NO2 was significantly associated with admissions for influenza in older than 65 years at lag 3. SO2 was not significantly associated with influenza; and O3, showed an association in individuals aged 13 to 19 years in lag 6. Despite of the well known susceptibility of the extreme age groups to air pollutants, this study suggests the relationship between concentrations of air pollutants and the occurrence of admissions to emergency departments for influenza in different age groups.