Tobacco and health fact sheet: Car and home smoke-free zone.

Sidestream smoke contains many cancer causing chemicals and other toxic substances. In some cases, their levels are 30 times higher than in the smoke inhaled by the smoker. For example, compared to mainstream smoke, sidestream smoke contains greater amounts of ammonia, benzene, carbon monoxide, nicotine and some carcinogens from the same amount of burnt tobacco. The health effects of exposure to passive smoking are well known. It increases the risk of lung cancer and heart disease as well as throat and chest infections.