Persistence of respiratory symptoms over 20 yrs in cotton and silk workers#
| Frequency of reported symptoms | ||||
| 0 | 1 | 2 | ≥3 | |
| Byssinosis | ||||
| Cotton workers | 240 (67.6) | 78 (22.0) | 33 (9.3) | 4 (1.1) |
| Silk workers | 348 (100) | 0 (0.0) | 0 (0.0) | 0 (0.0) |
| p-value¶ | <0.0001 | |||
| Chest tightness | ||||
| Cotton workers | 254 (71.6) | 74 (20.8) | 23 (6.5) | 4 (1.1) |
| Silk workers | 315 (90.5) | 28 (8.1) | 5 (1.4) | 0 |
| p-value | <0.0001 | |||
| Chronic bronchitis | ||||
| Cotton workers | 256 (72.1) | 48 (13.5) | 27 (7.6) | 24 (6.8) |
| Silk workers | 280 (80.5) | 46 (13.2) | 13 (3.7) | 9 (2.6) |
| p-value | 0.005 | |||
| Chronic cough | ||||
| Cotton workers | 258 (72.6) | 57 (16.1) | 21 (5.9) | 19 (5.4) |
| Silk workers | 285 (81.9) | 40 (11.5) | 13 (3.7) | 10 (2.9) |
| p-value | 0.03 | |||
| Dyspnoea+ | ||||
| Cotton workers | 213 (60.0) | 85 (23.9) | 34 (9.6) | 23 (6.5) |
| Silk workers | 245 (70.3) | 81 (23.3) | 18 (5.2) | 4 (1.2) |
| p-value | 0.0001 | |||
Data are presented as n (%), unless otherwise stated. #: calculation was carried out among 355 cotton and 348 silk workers who participated in at least four out of five surveys; ¶: Cochran–Armitage test for trend was used; +: 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.