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

Background : Exposure to air pollution negatively impacts respiratory health, but limited research exists on its short-term effects while simultaneously considering several pollutants measured with sensors. Objective : This study investigated the impact of air pollutants on lung function among 199 participants in Paris, France. Participants' exposure to black carbon (BC), nitrogen dioxide (NO ₂ ), nitrogen monoxide (NO), carbon monoxide (CO), ozone (O ₃ ), and particulate matter (PM _2.5 ) was recorded continuously. Lung function was assessed using spirometry tests conducted twice per day in the morning and evening over three days (N = 2504), measuring forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and the FEV1/FVC ratio. Methods : Air pollution levels were averaged over time windows from 15 minutes to 6 hours before the spirometry tests. Mixed-effect linear models were used to estimate the pollutants' associations with lung function. Results : Results showed that increased exposure to BC and PM2.5 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. Significance : This study highlights the detrimental short-term effects of air pollution, particularly BC and PM2.5, on lung function during daily mobility. Impact statement: This study provides evidence that short-term exposure to air pollutants – particularly black carbon (BC) and fine particulate matter (PM2.5) – can impair lung function. The findings demonstrate that even brief increases in BC and PM2.5 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.