Passive smoking affects both former smokers and people who have never smoked.

People who are exposed to the second-hand smoke from others' cigarettes are at increased risk of hearing loss. This is shown in a study involving more than 3,000 US adults published in the journal Tobacco Control.

Experts believe tobacco smoke may disrupt blood flow in the small vessels of the ear. This could starve the organ of oxygen and lead to a build-up of toxic waste, causing damage.

Former smokers 

In the study, more than 46% of former smokers who had been exposed to second-hand smoke had high-frequency hearing loss. 14% of former smokers who had been exposed to tobacco smoke by others were more likely to have impaired hearing in low- to mid-frequencies. 

Non smokers 

Researchers say, that although the risk of hearing loss was not as strong among people who had never smoked, nearly one-in-10 people in that group, or 8.6%, had low- to mid-frequency hearing loss, and 26% had high-frequency hearing loss.

The researchers from the University of Miami and Florida International University looked at the hearing test results of 3,307 non-smoking volunteers aged 20-69 - some who were ex-smokers and some who had never smoked in their lifetime. The tests measured range of hearing over low-, mid- and high-noise frequencies.

Checked for cotinine 

To assess passive smoke exposure, the volunteers had their blood checked for a by-product of nicotine, called cotinine, which is produced when the body comes into contact with tobacco smoke.

“Although previous studies have reported the link between active smoking and increased risk of hearing loss, this study found significantly increased adjusted odds for hearing loss by former smokers for both low-mid and high-frequency hearing loss. Furthermore, also never smokers exposed to second-hand smoke had increased risk of low-frequency hearing loss.” the authors write.

The data examined came from the National Health and Nutrition Examination Survey, a yearly household survey combined with a physical examination including hearing testing of a representative sample of the U.S. population.
Doctors have known for many years that people who smoke can damage their hearing.

Source: BBC News – www.bbc.co.uk and www.webmd.com