The information which follows has been excerpted from the EPA website. Since EPA's 1993 report which estimated the risks posed by ETS, numerous independent health studies have presented an impressive accumulating body of evidence that confirms and strengthens the EPA findings. It is widely accepted in the scientific and public health communities that secondhand smoke poses significant health risks to children and adults. Secondhand smoke is a mixture of the smoke given off by the burning end of a cigarette, pipe, or cigar, and the smoke exhaled from the lungs of smokers. This mixture contains more than 4,000 substances, more than 40 of which are known to cause cancer in humans or animals and many of which are strong irritants.
Secondhand smoke can cause lung cancer in nonsmokers.
Passive smoking is estimated by EPA to cause approximately 3,000 lung cancer deaths in nonsmokers each year. The risks to children are widely acknowledged. The conclusion that secondhand smoke causes respiratory effects in children is widely shared and virtually undisputed. Even the tobacco industry does not contest these effects in its media and public relations campaign. ETS exposure increases the risk of lower respiratory tract infections such as bronchitis and pneumonia.