Table 2 Age distribution, occupational exposure to airborne agents and educational level of the four populations.
| Population A (n = 2358) | Population B (n = 1184) | Population C (n = 539) | Population D (n = 331) | |
|---|---|---|---|---|
| Men | 1142 (48) | 595 (50) | 242 (45) | 154 (47) |
| Mean (SD) age (years) | 49.1 (14.4) | 48.1 (13.8) | 45.2 (13.2) | 46.3 (13.9) |
| Age 26–39 | 350 (30) | 189 (32) | 100 (41) | 61 (40) |
| Age 40–49 | 294 (26) | 160 (27) | 65 (27) | 36 (23) |
| Age 50–59 | 203 (18) | 116 (19) | 36 (15) | 27 (18) |
| Age 60–69 | 160 (14) | 77 (13) | 28 (12) | 19 (12) |
| Age 70–82 | 135 (12) | 53 (9) | 13 (5) | 11 (7) |
| Occupational exposure | ||||
| Yes | 706 (63) | 326 (56) | 109 (46) | 64 (43) |
| Educational level | ||||
| Primary | 192 (17) | 74 (13) | 15 (6) | 11 (7) |
| Secondary | 654 (58) | 332 (56) | 117 (49) | 74 (49) |
| University | 283 (25) | 183 (31) | 107 (45) | 66 (44) |
| Women | 1216 (52) | 589 (50) | 297 (55) | 177 (53) |
| Mean (SD) age (years) | 50.5 (15.1) | 48.1 (14.2) | 50.9 (15.4) | 52.5 (14.9) |
| Age 26–39 | 335 (28) | 177 (30) | 77 (26) | 37 (21) |
| Age 40–49 | 300 (25) | 163 (28) | 70 (24) | 43 (24) |
| Age 50–59 | 234 (19) | 127 (22) | 66 (22) | 42 (24) |
| Age 60–69 | 165 (13) | 61 (10) | 35 (12) | 24 (14) |
| Age 70–82 | 182 (15) | 61 (10) | 49 (16) | 31 (17) |
| Occupational exposure: | ||||
| Yes | 374 (32) | 142 (25) | 66 (23) | 39 (23) |
| Educational level | ||||
| Primary | 229 (19) | 93 (16) | 46 (16) | 28 (16) |
| Secondary | 705 (59) | 326 (56) | 156 (54) | 94 (54) |
| University | 263 (22) | 162 (28) | 89 (30) | 51 (30) |
Values are number (%) unless otherwise indicated.
Population A: parent population; population B: those without the cardinal respiratory symptoms of breathlessness, cough and wheeze; population C: never‐smokers without the cardinal respiratory symptoms of breathlessness, cough and wheeze; population D: never‐smokers without any respiratory symptoms.