Extensive research concludes that secondhand smoke is dangerous to human health. This smoke accumulates anywhere people smoke indoors, building up the concentration of dangerous chemicals. Everyone present is then forced to breathe smoke-filled air, and they in effect become passive or involuntary smokers. (Involuntary smoking has even been established as a cause of lung cancer in healthy nonsmokers, and as many as 5,000 nonsmokers a year get the disease as a result of secondhand smoke).

Babies in particular are vulnerable. Babies of parents who smoke at home run a much higher rate of lung diseases such as bronchitis and pneumonia. There also may exist an aggravation of asthma in children of smoking parents. Further research is being done.

The home is an important site of exposure. Parents should try to avoid smoking in the home - or quit smoking altogether. Outside the home, "no smoking" areas can be established in offices, restaurants and other establishments to reduce the risk. Ventilation should be increased in areas where people smoke in order to dilute smoke and odors. (Rooms where tobacco is smoked generally require 5-7 times more ventilation).