Associação entre a exposição de curto prazo à poluição do ar e mortalidade em idosos.

Abstract

This thesis explored the effects of short-term exposure to air pollutants in elderly mortality. The first manuscript aimed to quantify mortality displacement by estimating single lag and cumulative effects of air pollution on mortality using distributed lag models and the second manuscript aimed to evaluate the association between nitrogen dioxide (NO2) and mortality using single and multipollutant models. The data were analyzed as a daily time series of non-accidental and cause-specific mortality among elderly living in São Paulo, Brazil, between 2000 and 2011. Effects of particulate matter less than 10 µm (PM10), NO2, carbon monoxide (CO) and ozone (O3) were estimated in Poisson generalized additive models. In the first manuscript, the single lag effect of air pollutant exposure was evaluated at lags 0, 1 and 2 days. Distributed lag models with lags from 0 to lags 10, 20 and 30 days were used to assess mortality displacement and potential cumulative exposure effects. In the second manuscript, the single lag effect at lags 0 and 1 days and the cumulative effect from lag 0 to lag 10 days were evaluated in one-, two-, three- and four-pollutant models; the cumulative risk index (CRI) was additionally estimated for each model. About the first manuscript, PM10, NO2 and CO were significantly associated with non-accidental and cause-specific deaths in both single and cumulative lag models. Cumulative effects estimates up to lag 30 were essentially zero for non-accidental and circulatory deaths, while remaining elevated for respiratory, cerebrovascular and cancer deaths. Mortality displacement was less than 30 days for non-accidental and circulatory deaths and it was not found for other causes of death within 30 days. About the second manuscript, an association between NO2, PM10, CO and O3 exposures and non-accidental and cause-specific deaths was found in one-pollutant models. NO2 effects remained significant in multipollutant models for non-accidental and circulatory deaths. The estimated CRIs suggested that circulatory deaths were mainly associated with NO2 and respiratory deaths mainly with CO and O3, regardless the lag. For non-accidental deaths, multipollutant models were associated with the highest CRI with the main pollutants depending on the chosen lag. Air pollution mixture represented by NO2 had an effect on non-accidental and circulatory mortality, which was independent from PM10, CO and O3. The CRI was larger than the risks associated with single pollutants. In conclusion, the results from this thesis suggested that short-term exposure to air pollution is associated with an increase in number of daily elderly deaths in São Paulo.