Demographic data of participating subjects at the last follow-up survey
| Cotton workers | Silk workers | |
| Subjects n | 346 | 342 |
| Age yrs | 56.3±10.2 | 55.9±10.2 |
| Male | 155 (44.8) | 146 (42.7) |
| Height cm | 164.1±7.4 | 163.4±7.4 |
| Smokers | 119 (34.4) | 103 (30.1) |
| Pack-yrs# | 30.1±21.0 | 26.2±17.1 |
| Years worked | 25.5±7.8 | 28.6±9.4 |
| Retirement | 331 (95.7) | 332 (97.1) |
| Years since retired | 8.1±4.8 | 7.8±3.8 |
| Dust exposure mg·m−3·yr | 18.91±12.87 | |
| Endotoxin exposure EU·m−3·yr | 49122.60±45283.68 | |
| Pulmonary function | ||
| FEV1 L | 2.31±0.64 | 2.36±0.59 |
| FVC L | 2.95±0.77 | 2.94±0.74 |
| Respiratory symptoms | ||
| Chest tightness | 20 (5.8) | 2 (0.6) |
| Chronic bronchitis | 32 (9.3) | 26 (7.6) |
| Chronic cough | 35 (10.1) | 24 (7.0) |
| Dyspnoea¶ | 48 (13.9) | 79 (23.1) |
Data are presented as mean±sd and n (%), unless otherwise stated. FEV1: forced expiratory volume in one second; FVC: forced vital capacity. #: calculated among ever-smokers only; ¶: reaching ≥2 on a scale of 1–5, where 1 = no dyspnoea, 2 = having to walk slower than a person of the same age at an ordinary pace on level ground because of breathlessness, and 5 = dyspnoea at rest.