How often a smoker exposes someone to second hand smoking?

Second hand smoking refers to the smoke that people inhale from the burning end of others cigarette or the smoke breathed out by the smokers. Second hand smoke contains about 7,000 compounds, hundreds of which are harmful and roughly 70 of which can cause cancer.

Heath effects of Second hand Smoke -

There is no safe threshold of exposure to secondhand smoke; even brief exposure can be hazardous to health. Even among people who never smoke, secondhand smoke can cause -

• Children and newborns who are exposed to secondhand smoke are more likely to experience frequent and severe asthma attacks, respiratory infections, ear infections, and SIDS, among other health issues (SIDS).
• Each year, smoking during pregnancy causes more than 1,000 newborn deaths.
• Secondhand smoke has immediate negative effects on the heart and blood vessels and can cause lung cancer, or stroke for people who do not smoke.
• Nonsmokers who are exposed to secondhand smoke at work or at home have a 25–30% higher risk of getting heart disease than nonsmokers who do not smoke.
• Secondhand smoking is to blame for more than 8,000 stroke fatalities per year.
• Among non-smokers, secondhand smoke exposure contributes to more than 7,300 lung cancer deaths.