Passive smoking (also called secondhand smoke) is when people living and working around smokers unconsciously inhale smoke dust particles and various toxic substances. is passive smoking harmful? Passive smokers are more harmful! Because the concentration of harmful substances inhaled by passive smokers is not lower than that of smokers, but rather higher. The cold smoke exhaled by smokers contains one times more tar and four times more carbon monoxide than the hot smoke inhaled by smokers. According to studies, non-smokers who stay in a smoking environment for 1 hour are equivalent to smoking 1 cigarette themselves. Fifty percent of cancer patients from smoking are passive smokers, and the lung cancer rate of a wife whose husband smokes is 1.6-3.4 times higher than that of a non-smoker husband. Smoking can also affect a child’s appetite, and eating in a smoky environment on a regular basis can produce nausea and discomfort. Cigarettes are also a factor that affects the height of children. The average height of children in families where family members smoke less than 10 cigarettes per day is 0.45 cm shorter; in families where more than 10 cigarettes per day are smoked, the average height of children is 0.65 cm shorter; in families where more than 20 cigarettes per day are smoked, the average height of children is 0.91 cm shorter.