Exposure to ambient air pollution was associated with psychological distress, with black carbon showing a deleterious role independently of PM2.5 and NO2 in a large French adult cohort.
Key Findings
Results
Long-term exposure to PM2.5 was significantly associated with higher psychological distress.
IRR per IQR increase in PM2.5: 1.052 (95% CI: 1.014–1.092)
Mean PM2.5 exposure was 9.38 μg/m3 with an IQR of 2.6 μg/m3
Cross-sectional study of 104,146 French adults from the CONSTANCES cohort
Psychological distress assessed using the General Health Questionnaire-12 (GHQ-12) in 2019
Negative binomial models with covariate adjustments were used
Results
Long-term exposure to black carbon (BC) was significantly associated with higher psychological distress.
IRR per IQR increase in BC: 1.078 (95% CI: 1.055–1.101)
Mean BC exposure was 1.15 × 10-5/m with an IQR of 0.5 × 10-5/m
BC showed a numerically stronger association with psychological distress than PM2.5
Results
Long-term exposure to NO2 was significantly associated with higher psychological distress.
IRR per IQR increase in NO2: 1.082 (95% CI: 1.057–1.109)
Mean NO2 exposure was 19.1 μg/m3 with an IQR of 11.5 μg/m3
NO2 showed the strongest association among the three pollutants examined
Results
Black carbon had a deleterious association with psychological distress independently of PM2.5 and NO2, as assessed by a residuals method.
BC residuals regressed on PM2.5 were significantly associated with psychological distress: IRR 1.055 (95% CI: 1.039–1.071)
BC residuals regressed on NO2 were also significantly associated with psychological distress: IRR 1.067 (95% CI: 1.041–1.093)
The residuals method was used to isolate the independent contribution of BC from total particulate matter mass and NO2
Results
Associations between air pollution and psychological distress were stronger in men, elderly individuals, lower-educated individuals, and during the warm season.
Stratified analyses were conducted by age, sex, education, and season
These subgroup differences were observed across pollutants examined (PM2.5, BC, and NO2)
The study population included 104,146 adults from the French CONSTANCES cohort
Methods
Annual residential air pollutant concentrations were estimated using land-use regression models for all three pollutants.
Pollutants modeled included PM2.5, BC, and NO2 at each participant's residential address
Annual mean concentrations were: PM2.5 = 9.38 μg/m3, BC = 1.15 × 10-5/m, NO2 = 19.1 μg/m3
Land-use regression models were used to assign exposure estimates
Bitar Z, Pignon B, Lemogne C, de Hoogh K, Goldberg M, Schürhoff F, et al.. (2026). Long-term air pollution exposure and mental health in French adults of the CONSTANCES cohort: Role of black carbon independently of PM2.5.. Environmental research. https://doi.org/10.1016/j.envres.2026.123673