Third-hand smoke is generally considered to be residual¹ nicotine² and other chemicals left on a variety of indoor surfaces by tobacco smoke. This residue³ is thought to react with common indoor pollutants⁴ to create a toxic⁵ mix. This toxic mix of third-hand smoke contains cancer-causing substances, posing a potential health hazard to nonsmokers who are exposed to it, especially children.

三手烟（third-hand smoke）指吸烟之后残留在室内各种物体表面的尼古丁以及其它化学物质。这些残留物可能会与室内的其它污染物产生反应然后形成一种有毒的混合物。这种三手烟有毒混合物含有致癌物质，对接触到该物质的非吸烟人群，尤其是儿童，有潜在的健康威胁。

Studies show that third-hand smoke clings to hair, skin, clothes, furniture, drapes, walls, bedding, carpets, dust, vehicles and other surfaces, even long after smoking has stopped. Infants, children and nonsmoking adults may be at risk of tobacco-related health problems when they inhale⁶, ingest or touch substances containing third-hand smoke.

研究显示，在烟被掐灭很长时间以后，三手烟还是会残留在头发、皮肤、衣服、家具、窗帘、墙壁、床铺、地毯、灰尘、车辆以及其它物体的表面。婴幼儿和不吸烟的成人吸入、摄入或者接触到含有三手烟的物质后，就会有引发烟草类有关疾病的危险。