Retrospective modeling outdoor air pollution at a fine spatial scale in France, 1989-2008

Introduction: Exposure to air pollution has been associated to mortality and morbidity in numerous studies. However, few studies assessed retrospectively long-term exposure at a fine spatial scale. Aims: To contribute to the assessment of long-term exposure to air pollution of participants from the French GAZEL cohort, we estimated atmospheric PM10, PM2.5, NO2, SO2, C6H6 and O-3 levels at 2 km resolution over France, from 1989 to 2008. Methods: The spatiotemporal concentrations of selected air pollutants were estimated at a fine scale by combining (1) the CHIMERE chemistry-transport model (2) mesh refinement and (3) data assimilation with geostatistical analyzes. Assimilated concentrations were assigned to participants according to their residential zip codes, taking into account residential history. Results: Despite a decreasing trend in concentrations for all pollutant concentrations, levels remained high in some French regions, especially for PM, NO2 and O-3. Annual median concentrations at the cohort participants' zip code of PM10, PM2.5, NO2 and O-3 were decreased from 1989 to 2008 by 27%, 29%, 40% and 16%, respectively. The largest decreases occurred for SO2 (86%) and C6H6 (85%). Validation showed high correlations between observations and final modeled data (R above 0.75 in 2007) for PM10, NO2 and O-3. Conclusion: The modeling process enabled us to assess air pollution over 20 years (1989-2008) at a fine-geographical scale, with acceptable agreement being found between observations and models for all pollutants. (C) 2014 Elsevier Ltd. All rights reserved.