Air Pollution and Deaths among Elderly Residents of São Paulo, Brazil : An Analysis of Mortality Displacement

BACKGROUND: Evaluation of short-term mortality displacement is essential to accurately estimate the impact of short-term air pollution exposure on public health. OBJECTIVES: To quantify mortality displacement by estimating single-day lag effects and cumulative effects of air pollutants on mortality using distributed lag models. METHODS: We performed a daily time series of non-accidental and cause-specific mortality among elderly residents of São Paulo, Brazil, between 2000 and 2011. Effects of particulate matter smaller than 10 μm (PM10), nitrogen dioxide (NO2) and carbon monoxide (CO) were estimated in Poisson generalized additive models. Single-day lag effects of air pollutant exposure were estimated for lags 0, 1 and 2 day lags. Distributed lag models with lags of 0-10, 0-20 and 0-30 days were used to assess mortality displacement and potential cumulative exposure effects. RESULTS: PM10, NO2 and CO were significantly associated with non-accidental and cause-specific deaths in both single-day lag and cumulative lag models. Cumulative effect estimates for 0-10 days were larger than estimates for single-day lags. Cumulative effect estimates for 0-30 days were essentially zero for non-accidental and circulatory deaths, while remaining elevated for respiratory and cancer deaths. CONCLUSIONS: We found evidence of mortality displacement within 30 days for non-accidental and circulatory deaths in elderly residents of São Paulo. We did not find evidence of mortality displacement within 30 days for respiratory or cancer deaths