Non-smokers who repeatedly breathe in others' tobacco smoke get their sense of hearing affected, reports a new study.
Researchers studied a total of 3307 adults aged between 20 and 69.
The degree of hearing loss in each ear was assessed by testing the ability to hear pure tones over a range of frequencies from 500 Hz (low) to 8000 Hz (high).
Men, those who were older, and those with diabetes were significantly more likely to have high frequency hearing loss. And this was true of those who were former smokers and those who had never smoked.
But even after taking account of these factors, both former and passive smoking were associated with impaired hearing.
Former smokers were significantly more likely to have impaired hearing. The prevalence of low to mid frequency hearing loss among this group was 14 percent. And almost half (over 46 percent) had high frequency hearing loss (more than 25 decibels).
Although the risk was not as strong among those who had never smoked, almost one in 10 (8.6 percent) had low to mid frequency hearing loss and one in four (26.6 percent) had high frequency hearing loss.
And the stronger findings among former smokers suggested that continued passive smoking in this group, even at low levels, could continue the progression of high frequency hearing loss that began when they were active smokers, say the authors.
"Further research is required to determine whether [passive smoking] potentiates the effect of noise exposure and ageing on hearing," they conclude. "If this finding is independently confirmed, then hearing loss can be added to the growing list of health consequences associated with exposure to secondhand tobacco smoke."
The study was published online in Tobacco Control.