Association between improvement of air quality and change in lung function z-scores stratified by average body mass index (BMI) within the study period#
| Improvement in exposure | Underweight to normal (BMI <25 kg·m−2) | Overweight (BMI 25– <30 kg·m−2) | Obese (BMI ≥30 kg·m−2) | pinteraction-value | |
| Subjects n | 182 | 279 | 140 | ||
| Change in lung function | |||||
| FEV1 | NO2 (per 10 µg·m−3) | 0.09 (−0.09–0.28) | 0.15 (−0.01–0.31) | 0.14 (−0.04–0.31) | 0.585 |
| NOx (per 20 µg·m−3) | 0.04 (−0.10–0.18) | 0.10 (−0.01–0.21) | 0.06 (−0.08–0.19) | 0.741 | |
| PM2.5 (per 5 µg·m−3) | −0.08 (−0.20–0.05) | −0.01 (−0.11–0.10) | 0.00 (−0.15–0.15) | 0.337 | |
| PM10 (per 10 µg·m−3) | 0.03 (−0.15–0.21) | 0.13 (−0.03–0.28) | 0.13 (−0.08–0.34) | 0.369 | |
| FVC | NO2 (per 10 µg·m−3) | −0.07 (−0.25–0.11) | 0.04 (−0.11–0.19) | −0.01 (−0.17–0.16) | 0.563 |
| NOx (per 20 µg·m−3) | −0.02 (−0.15–0.11) | 0.05 (−0.05–0.15) | −0.02 (−0.15–0.10) | 0.745 | |
| PM2.5 (per 5 µg·m−3) | −0.06 (−0.18–0.06) | 0.00 (−0.11–0.10) | −0.04 (−0.18–0.10) | 0.840 | |
| PM10 (per 10 µg·m−3) | −0.09 (−0.27–0.08) | −0.01 (−0.16–0.14) | −0.06 (−0.26–0.14) | 0.882 | |
| FEV1/FVC | NO2 (per 10 µg·m−3) | 0.24 (0.04–0.45)¶ | 0.14 (−0.04–0.31) | 0.23 (0.04–0.43)¶ | 0.846 |
| NOx (per 20 µg·m−3) | 0.09 (−0.06–0.24) | 0.05 (−0.07–0.17) | 0.13 (−0.02–0.28) | 0.857 | |
| PM2.5 (per 5 µg·m−3) | 0.01 (−0.13–0.15) | −0.04 (−0.16–0.08) | 0.06 (−0.10–0.23) | 0.450 | |
| PM10 (per 10 µg·m−3) | 0.23 (0.03–0.43) | 0.16 (−0.02–0.33) | 0.32 (0.08–0.55)¶ | 0.378 |
Data are presented as β-estimates (95% CI) per indicated improvement in nitrogen dioxide (NO2), oxides of nitrogen (NOx), particulate matter with 50% cut-off aerodynamic diameter of 2.5 µm (PM2.5) and particulate matter with 50% cut-off aerodynamic diameter of 10 µm (PM10). pinteraction-value are given for the interaction terms between the continuous BMI measurements (average BMI within the study period) and air pollution. Adjusted for age, level of education, smoking (categorised as current, ex- or never-smoker) and exposure to second-hand smoke. #: n=601; ¶: significant association (p<0.05).