Impact of outdoor air pollution on respiratory health in two French studies ; Impact de la pollution de l’air extérieur sur la santé respiratoire dans deux études françaises

Although it is recognized that outdoor air pollution affects respiratory health, the underlying biological mechanisms that explain these associations are still poorly understood, and the associations between long-term exposure to outdoor air pollution, whether from road traffic or industry, and lung function are poorly studied in adults.The general aim of this thesis was to study the impact of outdoor air pollution on the respiratory health of adults in two French epidemiological studies: the EGEA case-control and family study and the ELISABET general population study. The association between long-term exposure to outdoor air pollution and different asthma phenotypes and the role of the biological pathway of oxidative stress in these associations were studied in EGEA. In the cross-sectional analyses, ozone (O3) and road traffic were associated with current asthma. The level of 8-isoprostane (8-iso), a biomarker of damages measured in exhaled breath condensate, increased with exposure to particulates with a diameter of less than 2.5 μm (PM2.5) and decreased with exposure to O3 and O3-summer. Levels of fluorescent oxidation products (FlOPs), biomarkers of damages measured in plasma, increased with exposure to nitrogen dioxide (NO2), nitrogen oxides, PM10 and PM2.5. A high level of 8-iso was associated with current asthma and high levels of FlOPs were associated with poor asthma control. In longitudinal analyses, exposure to O3 increased FlOPs levels, and FlOPs levels were associated with persistent asthma. The study of the role of FlOPs as mediators in the association between O3 and persistent asthma showed that O3 was associated with persistent asthma through an indirect effect mediated by plasma FlOPs, representing 41% of the total effect.The association between long-term exposure to outdoor air pollution and lung function was investigated in ELISABET and EGEA. In ELISABET, exposure to NO2 and PM10 was associated with a decrease in forced expiratory volume in one second (FEV1), forced vital capacity (FVC), ...