Healthcare experts are aware that smoking can cause hearing impairment, but now there is a study to prove that people who get exposed to second hand smoke can also develop hearing loss.

The study published in the journal Tobacco Control, looked at more than 3,000 adults in the US found that passive smoking has an impact on the health and hearing of the person. Smoke actually restricts the blood flow in the small vessels of the ear, which blocks the oxygen flow to the organ and toxins get built up, which causes the damage.

"We really do not know exactly how much smoke you need to be exposed to in order to be at increased risk. But we do know that the threshold for damage is very low,” said Dr David Fabry, who led the research. "Really, the safe level of exposure is no exposure."

The researchers tested both nonsmokers and ex-smokers to get the results. First their blood was checked for byproduct of nicotine, called cotinine, which gets formed inside the body of those exposed to nicotine smoke. The tests measured range of hearing over low, mid and high noise frequencies. The results showed that passive smokers were more prone to hearing problem than others. So the doctors advise smokers to be more understanding when lighting up the next time.