| Total | Never-smokers | Former smokers | Current smokers | |
| Adult airway obstruction n (%) | ||||
| No asthma | 209 (1.0) | 33 (0.4) | 42 (0.9) | 134 (1.8) |
| Early-onset asthma | 138 (10.1) | 59 (8.8) | 36 (12.2) | 43 (10.7) |
| Late-onset asthma | 162 (8.3) | 57 (6.2) | 35 (7.6) | 70 (12.3) |
| Total | 509 (2.1) | 149 (1.5) | 113 (2.1) | 247 (3.0) |
| Baseline FEV1 L | ||||
| No asthma | 3.77±0.8 | 3.78±0.9 | 3.80±0.8 | 3.75±0.8 |
| Early-onset asthma | 3.61±0.9 | 3.63±0.9 | 3.52±0.8 | 3.62±0.8 |
| Late-onset asthma | 3.34±0.8 | 3.38±0.9 | 3.38±0.8 | 3.24±0.8 |
| Total | 3.73±0.8 | 3.73±0.9 | 3.71±0.8 | 3.75±0.8 |
| FEV1 change¶ mL·year−1 | ||||
| No asthma | −28.72±32.42 | −27.05±31.47 | −28.62±30.44 | −31.04±35.13 |
| Early-onset asthma | −29.49±44.39 | −30.97±44.06 | −24.85±42.57 | −31.92±47.25 |
| Late-onset asthma | −28.55±41.96 | −28.52±40.69 | −27.05±40.95 | −30.18±45.42 |
| Total | −28.75±34.17 | −27.46±33.50 | −28.27±32.30 | −31.01±36.60 |
Data are presented as mean±sd unless otherwise stated. #: pre-bronchodilator FEV1/forced vital capacity ratio <70% and FEV1 <80% predicted measured either at the European Community Respiratory Health Survey (ECRHS) I or II; measurements from both surveys are used, thus one individual may contribute with two measurements. ¶: FEV1 in the ECRHS II minus FEV1 in ECRHS I.