Characteristics of the study participants by dense traffic exposure category (distance to the nearest road with more than 10 000 vehicles per day).
| Dense traffic exposure | |||
|---|---|---|---|
| Low (>500 m) | Medium (75–500 m) | High (<75 m) | |
| All participants (n=5441) | n=2410 | n=2668 | n=363 |
| Mean (SD) | Mean (SD) | Mean (SD) | |
| Age, years | 51.8 (11.0) | 51.5 (11.6) | 50.1 (12.4) |
| Body mass index (BMI) | 26.2 (4.0) | 26.0 (4.1) | 26.2 (4.5) |
| Lung function | |||
| FEV1 (% predicted) | 96.9 (13.8) | 96.2 (13.5) | 96.0 (13.6) |
| FVC (% predicted) | 98.5 (12.5) | 98.2 (12.2) | 97.7 (12.9) |
| Per cent | Per cent | Per cent | |
| Sex (% women) | 52.2 | 54.4 | 54.5 |
| Smoking history | |||
| Never smoked (n=2509) | 47.2 | 45.6 | 43.0 |
| Former smoker (n=2023) | 37.0 | 37.5 | 36.4 |
| Current smoker (n=909) | 15.9 | 16.9 | 20.7 |
| Highest formal education | |||
| Primary education (n=664) | 13.1 | 11.7 | 9.9 |
| Upper primary education (n=184) | 3.7 | 3.4 | 1.4 |
| Vocational school (n=404) | 7.6 | 7.5 | 5.5 |
| High school (n=1254) | 24.3 | 22.3 | 19.8 |
| University (n=2048) | 34.1 | 39.5 | 50.4 |
| Other education (n=887) | 17.1 | 15.5 | 15.7 |
| Obstructive pulmonary disease* (n=533) | 9.0 | 10.3 | 10.7 |
*Reported current asthma or fulfils criteria for chronic obstructive pulmonary disease (COPD) in regular spirometry test without reversibility testing.
BMI, body mass index; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity.