Why is SHS harmful?

Harmful Chemicals and Carcinogens
SHS, secondhand smoke, contains all the harmful chemicals and carcinogens as any tobacco smoke does. All the harmful effects of smoke that damage the heart and lungs of smokers also act on non-smokers who inhale SHS. The more SHS a non-smoker inhales, the closer he or she comes to being a "smoker" in terms of disease risk. One of the major conclusions of the 2006 Surgeon General's Report is that "there is no safe level of secondhand smoke."

Gases Spread Very Quickly
Employees who work in a building where smoking is allowed, even if it is confined to a small area of the building, are still putting themselves at risk of disease. The reason for this is that the harmful chemicals in SHS are rapidly diffusing gases. The molecules spread very rapidly throughout the building to enter every room within a matter of seconds. Consider a swimming pool divided by ropes into a peeing and non-peeing area. No one would consider himself safe from smelling like urine simply by staying in the non-peeing area. Now consider the fact that gases spread and mix much more quickly than liquids.

Tobacco smoke and SHS contain many known human carcinogens (cancer-causing chemicals) and over 200 toxins (substances proven to be poisonous to humans).

Cigarette Smoke is Radioactive
We have known since the 1960's that tobacco contains polonium 210, a highly radioactive element that is known to cause cancer. Here is an article from the New York Times about polonium in cigarettes: [New York Times]

Breathing Secondhand Smoke is a Serious Risk for Dementia
Recent research suggests that secondhand smoke increases your risk of dementia by as much as 44%. [HealthDay]