The PAISA Project: Studying the Relationships between Air Pollution, Socioeconomic Status, and Asthma Attacks

SM2-PD-04 Socioeconomic gradients in health are well documented in developed countries but incompletely explained. Besides, many environmental exposures are suspected to be health risk factors, while relatively few are well established. However, research in these different domains is essentially carried out independently. Since a part of health socioeconomic gradients might be explained by environmental exposures, our objective is to explore relationships between socioeconomic status (SES), environmental exposures and health. We chose to study a short-term effect of an environmental exposure, that is, asthma attacks and atmospheric pollution, in relation to SES. Such a work on asthma was never conducted in Europe. The design of our studies is ecologic and will test the associations between levels of atmospheric pollution and 1) emergency visits of physicians for asthma attacks and 2) figures of respiratory drug sales in relation to SES. The setting is an eastern French conurbation of 450,000 inhabitants. The statistical unit is the smallest area (IRIS) for which SES data are available through the French National Institute of Statistics (INSEE). Data on emergency visits have been obtained from the 2 emergency and healthcare networks operating in the conurbation for the years 2000 to 2002. Data on respiratory drug sales for 2004 have been obtained from the 3 French Medical Insurance Systems. Levels of PM10, O3, NO2, and SO2 in each IRIS will be modelled on an hourly basis from emission inventories, meteorologic data, and pollution measurements of the Local Air Monitoring Association using the deterministic model ADMS-Urban. An uncertainty and sensitivity analysis of the air pollutants modelling will be carried out, allowing analyzing the effects of modelling uncertainty on observed associations. We'll study 1) the distribution of both health indicators across IRISes exhibiting contrasted SES; 2) the distribution of ambient air pollutants concentrations across IRISes exhibiting contrasted SES; and 3) the modulating role of IRISes SES on the relationship between air pollution levels and asthma attacks using both case crossover and time-series approaches. Potential confounding factors (influenza epidemics, pollen release bursts, and meteorology) will be taken into account in the analyses. Age- and sex-specific analyses will be carried out as far as possible, depending on the number of health events registered. As health data have been collected during the first 2006 quarter, the first results on the distribution of health indicators across IRISes exhibiting contrasted SES will be presented.