Evaluation of the effects of air pollutants on lung function using ambulatory monitor data from the MobiliSense Project

Background: Air pollution is a major public health concern associated with increased respiratory morbidity and mortality worldwide. It negatively impacts respiratory health, yet limited research based on accurate assessments with multiple sensors exists on its short-term effects. In this study we investigate the short-term association between exposure to multiple air pollutants and lung function in adults during daily mobility. Methods: Data on daily activities of 199 participants of the MobiliSense cohort living in the metropolitan area of Paris were collected between 2018 and 2020. Participants were equipped of two portable ambulatory monitors of air pollutants, a GPS receiver and an accelerometer during their mobility. Exposure to black carbon (BC), nitrogen dioxide (NO₂), nitrogen monoxide (NO), carbon monoxide (CO), ozone (O₃), and particulate matter (PM₂.₅) was recorded continuously. Lung function was assessed using spirometry tests conducted in the morning and evening over three days (N = 2,504), measuring forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC), and FEV₁/FVC ratio. Mixed-effects linear models were applied to assess the association between pollutant exposure at varying time lags (15 minutes to 6 hours prior to spirometry testing) and lung function outcomes. Results : Multipollutant models showed that increased exposure to BC and PM _2.5 was associated with a reduced lung function. A 1 μg/m ³ increase in BC within 1 or 2 hours prior to testing was associated with a decrease in FEV1 by 0.016 (95% CI -0.024, -0.008) and 0.021 (95% CI -0.034, -0.007) respectively. Similarly, increases in BC exposure over 2 hours to 4 hours were associated with a decrease in the FEV1/FVC ratio. Additionally, PM2.5 exposure 15 or 30 minutes or 1 hour before testing was linked to a 0.60 (95% CI -1.30, -0.03), 0.70 (95% CI -1.39, -0.09) and 0.50 (95% CI -1.10, -0.01) percentage points reduction in the FEV1/FVC ratio. Ozone (O3) was positively associated with FEV1 and FVC. No associations were found for other pollutants or time windows. Conclusion: This study provides evidence that short-term exposure to air pollutants – particularly BC and PM _2.5 – can impair lung function. The findings demonstrate that even brief increases in BC and PM _2.5 during daily mobility are associated with measurable reductions in FEV1 and the FEV1/FVC ratio. By assessing multiple pollutants across short exposure windows (15 minutes to 6 hours), this study strengthens causal inference regarding rapid respiratory effects and underscore the health relevance of transient pollution peaks encountered in urban environments, particularly from traffic emissions. Clinical trial number : not applicable.