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

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. 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 O3 levels at 2 km resolution over France, from 1989 to 2008. 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. Despite a decreasing trend in concentrations for all pollutant concentrations, levels remained high in some French regions, especially for PM, NO2 and O3. Annual median concentrations at the cohort participants' zip code of PM10, PM2.5, NO2 and O3 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 O3. 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. •We model French air quality to assess long-term health effects on large cohort.•We assess concentrations of six air pollutants at 2 km resolution from 1989 to 2008.•We use CHIMERE/MM5, mesh refinement, data assimilation and geostatistical analyses.•We validate data of air quality with French air quality monitoring network.