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Kabat, Davey Smith, "Environmental tobacco smoke and tobacco related mortality in a prospective study of Californians, 1960-98," British Medical Journal (15 May 2003)

Limit your exposure to the sun

Although CO levels less than 10ppm are traditionally considered to define non-smoking, various studies have found that the figure that marks the cut-off point is around 45ppm.26,29,30 Therefore, any subject who shows CO levels higher than 5ppm should be considered a smoker, providing that the examination has been correctly carried out and all cases of false positive co-oximetry have been ruled out (Table 4)

It is expelling all the pollutants from cigarettes accumulated over years of smoking