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

Abstract 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 PM 10 , PM 2.5 , NO 2 , SO 2 , C 6 H 6 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, NO 2 and O 3 . Annual median concentrations at the cohort participants' zip code of PM 10 , PM 2.5 , NO 2 and O 3 were decreased from 1989 to 2008 by 27%, 29%, 40% and 16%, respectively. The largest decreases occurred for SO 2 (86%) and C 6 H 6 (85%). Validation showed high correlations between observations and final modeled data (R above 0.75 in 2007) for PM 10 , NO 2 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.