Prevalence (numerator/denominator) of hearing loss* according to age, occupational exposure to noise, and smoking in 4624 male workers in a steel factory in Japan, 1999
| Age group | ||||
|---|---|---|---|---|
| Occupational noise exposure | Smoking status | ≤39 y | 40–49 y | 50–60 y |
| *Hearing threshold: 1000 Hz, >25 dB; 4000 Hz, >40 dB. | ||||
| 1000 Hz | ||||
| No | Non-smoker | 0.7 (4/560) | 4.6 (23/499) | 9.2 (24/262) |
| Smoker | 1.0 (6/578) | 4.1 (39/954) | 12.5 (48/385) | |
| Yes | Non-smoker | 0.8 (1/120) | 6.4 (11/172) | 16.3 (13/80) |
| Smoker | 2.4 (8/329) | 6.7 (35/520) | 11.5 (19/165) | |
| 4000 Hz | ||||
| No | Non-smoker | 1.6 (9/560) | 9.4 (47/499) | 25.2 (66/262) |
| Smoker | 1.4 (8/578) | 18.3 (175/954) | 34.3 (132/385) | |
| Yes | Non-smoker | 0.8 (1/120) | 18.6 (32/172) | 43.8 (35/80) |
| Smoker | 2.7 (9/329) | 29.8 (155/520) | 52.7 (87/165) | |