Researchers from the University of Miami found non-smokers exposed to second hand smoke (SHS) have a 14 per cent increased risk of hearing loss at lower frequencies.
Experts believe tobacco smoke may interfere with the functioning of the cochlear.
What did researchers find?
Previous research has shown that current smokers are up to 1.7 times more likely to develop hearing loss.
But it was unknown whether passive smokers are similarly affected.
To test this, researchers used data on SHS exposure, hearing ability and noise exposure history collected from 3,307 non-smoking adults.
Participants were deemed to be SHS-exposed if serum cotinine levels reached 0.05ng/ml or above. Smokers typically have levels at 3ng/ml.
Results showed prevalence of low-frequency hearing loss was 8.6 per cent among never smokers and 14 per cent in former smokers.
For high frequency hearing loss prevalence was 8.6 per cent and 26.6 per cent in the two groups respectively.
The largest risk was in former smokers exposed to SHS. This group had 40 per cent increased risk of high-frequency hearing loss.
The study authors said the threshold toxic exposure level for hearing loss was very low.
'Although an active smoker is personally responsible for his/her own toxic exposures, involuntary exposures via SHS may also place never smokers and former smokers at increased risk for hearing loss,' they said.
How significant are the findings?
The authors said policy makers should continue to take action to prevent SHS exposure in settings such as the workplace and home.
They said that further studies could examine potential sources of SHS exposure.
Dr Ralph Holme, head of biomedical research at the Royal National Institute for Deaf People, said the study was important because it highlighted the increased risks to passive smokers.
'Before you next light up a cigarette, consider how it could impact not only on your own long-term hearing but your friends' and relatives' too.'
- Passive smoking increases the risk of hearing loss by up to 40 per cent.
- Very low levels of SHS can impair hearing.
- Researchers believe prevention of passive smoking can reduce related hearing loss.