Second-hand smoke: About second-hand smoke

There is no safe level of exposure to tobacco smoke. Exposure to the smoke from the lit end of a tobacco product such as a cigarette, pipe, cigar, hookah, as well as to the smoke exhaled by person who smokes, increases your risk of negative health effects.^{End Note 1}

On this page

• What is second-hand smoke?
• Facts about second-hand smoke

What is second-hand smoke?

Second-hand smoke refers to both the smoke coming directly from the burning end of a tobacco product and the smoke exhaled by a person who is smoking. In both situations, the tobacco smoke contains a composition of more than 7,000 chemicals, of which hundreds are toxic and more than 70 are known to can cause cancer. ^{End Note 2End Note 3End Note 4End Note 5}

The formation of most of these chemicals, including carbon monoxide, benzene, formaldehyde and hydrogen cyanide, occurs during the combustion process in every smoked tobacco product. Other substances, such as lead, nitrosamines and nicotine, occur naturally in the tobacco leaf and are released as the tobacco burns.

Most of the smoke from a lit cigarette is not inhaled by the person who smokes. It fills the air around them, as the cigarette continues to burn. This poses a risk to everyone's health in the area. For more information about the specific health effects of second-hand smoke, see the Health effects of smoking and second-hand smoke page.

Facts about second-hand smoke

Second-hand smoke is particularly dangerous in enclosed spaces

Tobacco smoke toxins remain in a room long after the original exposure has occurred. Opening windows or using a fan, air purifier or air freshener cannot remove all cancer-causing chemicals and toxins in the air. These harmful toxins can also cling to different materials, such as:

• rugs
• curtains
• clothing
• food
• furniture

Smoking in enclosed spaces (indoors - like in a home - or car) increases the risks to your health. This is because the level of second-hand smoke is higher in enclosed spaces.

Some groups are at increased risk from second-hand smoke

Exposure to second-hand smoke hurts everyone however, pregnant people and their babies, infants and children are particularly at risk to suffer serious health impacts. Learn more about exposure to second-hand smoke during pregnancy and the health impacts for children.

The only way to protect yourself from second-hand smoke is to avoid exposure

There is no safe level of exposure to second-hand smoke.

• Quit smoking or help someone quit smoking. If you are not ready to quit, avoid smoking around other people.
• Make your home and car smoke-free. If you live in a multi-unit dwelling, find out how to make your home smoke-free in a multi-unit residence.
• Avoid areas where people are smoking.