What is Passive Smoking and Why Should You Care?

Passive smoking is the involuntary inhalation of smoke from tobacco products such as cigarettes, cigars, and the like. In some areas it is called secondhand smoke or environmental tobacco smoke. Persons who live in close quarters with someone who smokes are known to be affected by passive smoking, including spouses, bhildren, and even pets.
Is passive smoking really harmful?
Much research has