Ito, K; Mathes, R; Ross, Z; Nádas, A; Thurston, G; Matte, T
Background: Recent time-series studies have indicated that both cardiovascular mortality and hospitalizations were associated with particulate matter (PM). However, seasonal patterns of PM associations with these outcomes are not consistent, and PM components responsible for these associations have not been determined. We investigated this issue in New York City, where PM originates from regional and local combustion sources. Methods: We analyzed daily deaths and emergency hospitalizations for cardiovascular diseases (CVD) among those aged 40+ for their associations with fine particle mass (PM2.5), its chemical components, nitrogen dioxide (NO2), carbon monoxide, and sulfur dioxide for the years 2000-2006 using Poisson model adjusting for temporal/seasonal trends, temperature effects, and day-of-week. We estimated excess risks per inter-quartile-range increases at lag 0 through 3 days for warm (April-September) and cold (October-March) seasons. Results: The CVD mortality series exhibit strong seasonal trends, while the CVD hospitalization series show a strong day-of-week pattern. These outcome series were not correlated with each other but were individually associated with a number of PM2.5 chemical components from regional and local sources, each with different seasonal patterns and lags. Coal combustion-related components (e.g., selenium) were associated with CVD mortality in summer and CVD hospitalizations in winter, whereas elemental carbon and NO2 showed associations with these outcomes in both seasons. Conclusion: Local combustion sources, including traffic and residual oil burning, may play a year-round role in the associations between air pollution and CVD outcomes, but transported aerosols may explain the seasonal variation in associations shown by PM2.5 mass.
