7. Second Hand Smoke
Secondhand smoking, breathing in of environmental tobacco smoke (ETS), is also called passive smoking. It is when a person breathes in smoke given off into the environment by other people.
Secondhand smoke or ETS is a combination of side stream smoke coming straight from the burning tobacco and the mainstream smoke that is exhaled by the smoker. It comprises of over 4000 chemical constituents, a large proportion of which are the inducers of respiratory illnesses and around 40 are known or suspected carcinogens. The US Environmental Protection Agency (EPA) has classified ETS as a class A (known human) carcinogen along with other known carcinogens such as arsenic, asbestos and benzene etc.
Secondhand Smoking is Injurious
ETS is unfiltered, thus the levels of carcinogens in it are much more than in smoke inhaled directly by an active smoker. Smoking of a cigarette produces smoke from two major places, mainly from the tip of cigarette and from the rest of the cigarette as the hot vapors liberated through the cigarette and its filter. About 70% to 80 % of ETS is from the burning tip of cigarette and comprises of the highest levels of nicotine, carbon monoxide, tar and various other carcinogens. Therefore, a constant exposure to an ETS is apparently even more injurious than directly smoking a cigarette for an equivalent period.
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