Secondhand smoke (SHS) has the same harmful chemicals that smokers inhale, says the American Cancer Society.
Non-smokers who breathe SHS take in nicotine and toxins, and are at risk for cancer.
Cancer is not the only illness that SHS can cause. It affects the heart and blood vessels, also increasing the risk of heart attack and stroke in non-smokers.
Studies show that children exposed to SHS get sick more often, have more lung infections and are more likely to cough, wheeze and have shortness of breath.