Table 4

Prevalence rate ratio of hearing loss for the combinations of occupational exposure to noise and smoking among 4624 male workers in a steel factory in Japan, 1999

Occupational noise exposurePRR*95% CIPRR95% CI
PRR, prevalence rate ratio; CI, confidence interval.
*Calculated by the Cochran-Mantel-Haenszel method, stratified by age group.
1000 Hz
    No1Reference1.140.82 to 1.58
    Yes1.550.98 to 2.451.501.05 to 2.15
4000 Hz
    No1Reference1.571.31 to 1.89
    Yes1.771.36 to 2.302.562.12 to 3.07