Secondhand smoke — also known as environmental tobacco smoke — includes the smoke that a smoker exhales (mainstream smoke) and the smoke that comes directly from the burning tobacco product (sidestream smoke)
Secondhand smoke contains toxic chemicals, including:
Ammonia, used in cleaning products
Butane, used in lighter fluid
Carbon monoxide, found in car exhaust
Chromium, used to make steel
Cyanide, used in chemical weapons
Formaldehyde, an industrial chemical
Lead, a toxic metal
The dangerous particles in secondhand smoke can linger in the air for hours or even longer. It isn’t just the smoke that’s a concern, though. The residue that clings to a smoker’s hair and clothing, as well as cushions, carpeting and other goods — sometimes referred to as thirdhand smoke — also can pose risks, especially for children.