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Time Scale Effects in Acute Association between Air-Pollution and Mortality
Citation:
Valari, M., L. Martinelli, E. Chatignoux, J. L. CROOKS, AND V. GARCIA. Time Scale Effects in Acute Association between Air-Pollution and Mortality. GEOPHYSICAL RESEARCH LETTERS. American Geophysical Union, Washington, DC, 38(L10806):1-5, (2011).
Impact/Purpose:
The National Exposure Research Laboratory′s (NERL′s) Atmospheric Modeling and Analysis Division (AMAD) conducts research in support of EPA′s mission to protect human health and the environment. AMAD′s research program is engaged in developing and evaluating predictive atmospheric models on all spatial and temporal scales for forecasting the Nation′s air quality and for assessing changes in air quality and air pollutant exposures, as affected by changes in ecosystem management and regulatory decisions. AMAD is responsible for providing a sound scientific and technical basis for regulatory policies based on air quality models to improve ambient air quality. The models developed by AMAD are being used by EPA, NOAA, and the air pollution community in understanding and forecasting not only the magnitude of the air pollution problem, but also in developing emission control policies and regulations for air quality improvements.
Description:
We used wavelet analysis and generalized additive models (GAM) to study timescale effects in the acute association between mortality and air-pollution. Daily averages of measured NO2 concentrations in the metropolitan Paris area are used as indicators of human exposure to urban air pollution from 2000 to 2004. The NO2 time series was decomposed with wavelet analysis to six independent variables representing different durations of population exposure. We used these variables as predictors in a mortality regression model and compared the coefficients estimated for the different timescales. We found a strong dependency of the exposure-response function on the duration of the air-pollution event. In contrast to previous studies that showed a monotone increase in the relationship between exposure to air-pollution and mortality from shorter to longer timescales, our results show a non-linear response suggesting that the overall acute effect consists of two discrete patterns: a short-term response (2 to 15 days) where mortality relative risks decrease to near null values with the duration of the air-pollution event; an intermediate timescale pattern (16 to 55 days) where mortality relative risk climbs back up to positive levels. The revealed pattern suggests that the overall acute effect of air-pollution on mortality reflects not only a short-term mortality displacement in a population already at high death risk due to chronic conditions but also the transition into this pool from the healthy population.
URLs/Downloads:
Geophysical Research Letters
Time Scale Effects in Acute Association between Air-Pollution and Mortality (PDF, NA pp, 3415 KB, about PDF)