Methods in the three general populations
| France | The Netherlands | Norway | |
| 1975 | 1965–9 | 1985–8 | |
| 7 Cities | Urban or rural | ||
| Pulmonary spirometer | Dry spirograph Vitalograph | Lode spirograph 53 | Gould 2100 spirometer |
| Job classification | INSEE (French), 4 digits | Dutch, 4 digits | Nordic, 3 digits |
| Population in each survey | 20310 Men and women | 3477 Men | 653 Men |
| Subjects excluded (n (%)) | 8522 (42.0) | 1843 (53.0) | 258 (39.5) |
| Reasons of these exclusions (n (%)): | |||
| Aged <25 or >64 (Norway) | — | 816 (44.3) | 185 (71.7) |
| Lack of answer or no occupation | 3896 (45.7) | 165 (9.0) | 5 (1.9) |
| Lack of answer to exposure | 113 (1.3) | 31 (1.7) | 4 (1.6) |
| FEV1 not performed | 1298 (15.2) | 525 (28.5) | 1 (0.4) |
| Without good tracings | 2981 (35.0) | 173 (9.4) | 14 (5.4) |
| Lack of answer to height or smoking | 81 (1.0) | 12 (0.7) | 3 (1.2) |
| Occupation with <2 subjects | 154 (1.8) | 121 (6.6) | 46 (17.8) |
| Analyses performed on | 6217 Men/5571 women | 854 Men/780 men | 395 Men |