Hearing among male firefighters: a comparison with hearing data from screened and unscreened male population

We investigated whether hearing loss is associated with firefighting. We conducted cross-sectional study comparing hearing threshold levels (HTLs) of 912 male firefighters with two hearing databases obtained from an otologically normal male Korean population (KONP) and a non-industrial noise-exposed male Korean population (KNINEP), considering age and the main roles of firefighters. Firefighters' age-adjusted HTLs were significantly worse than those of KONP (prevalence ratio (PR)=5.29, P<0.001)but not different from those of KNINEP (PR=0.99, P=0.550). Rescuers (PR=1.005, P<0.001) had worse hearing than the KNINEP after age adjustment. Comparison of firefighters' HTLs (50th and 90th percentiles) with those of KONP and KNINEP by age and frequency showed that firefighters' HTLs had significant increases (poorer hearing) across most age groups and frequencies compared with KONP. Compared with KNINEP, firefighters' HTLs were worse in the younger age groups (<45 years) but not different in the older age groups (>45 years). In conclusion, the hearing thresholds of younger firefighters and rescuers were worse than expected by normal aging alone. Future research should include longitudinal studies to consider variable risk factors, such as military service, smoking, and so on.