From WebMD:

Tobacco smoke residue lurking in carpets, upholstered furniture, and on other everyday surfaces can react with common chemicals in indoor air to form cancer-causing substances, according to a new study in the Proceedings of the National Academy of Sciences.

Tobacco smoke residue on everyday surfaces has recently been dubbed “thirdhand” smoke. Researchers say their findings further demonstrate that exposure to thirdhand smoke is a potential long-term health hazard. It is especially concerning for infants and toddlers, who tend to have more frequent contact with the contaminated surfaces when crawling and playing.

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