Increased Risk of Sensorineural Hearing Loss as a Result of Exposure to Air Pollution.

Whether exposure to air pollution is associated with developing sensorineural hearing loss (SHL) remains controversial. Using data from the National Health Insurance Research Database, we recruited a total of 75,767 subjects aged older than 20 years with no history of SHL from 1998 to 2010, and they were followed up until SHL was observed, they withdrew from the National Health Insurance program, or the study ended. The subjects were evenly exposed to low-level, mid-level, and high-level carbon monoxide (CO) and nitrogen dioxide (NO2). The incidence rate ratio of SHL for patients exposed to high-level CO was 1.24 (95% confidence interval (CI) = 1.14-1.36). The NO2 pollutants increased the incidence rate ratios of SHL in mid-level NO2 and high-level NO2 exposures by 1.10 (95% CI = 1.10-1.32) and 1.36 (95% CI = 1.24-1.49) times, respectively. The adjusted hazard ratio (adj. HR) of SHL in patients exposed to high-level CO was 1.45 (95% CI = 1.31-1.59), relative to that of patients exposed to low-level CO. Compared to patients exposed to low-level NO2, patients exposed to mid-level NO2 (adj. HR = 1.40, 95% CI = 1.27-1.54) and high-level NO2 (adj. HR = 1.63, 95% CI = 1.48-1.81) had a higher risk of developing SHL. The increased risk of SHL following the increased concentrations of air pollutants (CO and NO2) was statistically significant in this study. In conclusion, the subjects' exposure to air pollution exhibited a significantly higher risk of developing SHL in Taiwan.