Being around tobacco smoke is bad for you, even if it's someone else's smoke.
When someone smokes a cigarette, most of the smoke doesn't go into their lungs. It goes into the air, where anyone nearby can breathe it.
Smoking is banned in many public places. But many people are still exposed to secondhand smoke, especially children who live with parents who smoke. Even people who try to be careful about where they light up may not protect those around them.
After 48 hours: Your ability to taste and smell starts to return.
After 72 hours: The bronchial tubes (airways) relax.
After two weeks to three months: Your circulation improves.
After one to nine months: Cilia (tiny hairs) in the lungs regrow, increasing the lung's capacity to handle mucus, clean itself, and reduce infection. Coughing, sinus congestion, fatigue, and shortness of breath also decrease.
After one to five years: Your risk of dying from heart disease is cut to half that of a lifelong smoker's risk.
After 10 years: Your risk of dying from lung cancer drops to almost the same rate as that of a lifelong nonsmoker. Your risk for mouth, larynx, and other cancers decreases.