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Second-hand smoke refers to smoke from a person’s cigarette, pipe or cigar. It is also known as passive smoke, environmental smoke and involuntary smoke.

There are two main types:

  • side-stream smoke — smoke released from the tip of the cigarette
  • mainstream smoke — smoke exhaled by the smoker

Effects of second-hand smoke on adults

Second-hand smoke contains more than 7000 chemicals, with 69 known to cause cancer.

There is no safe level of exposure to second-hand smoke. Second-hand smoke increases the risk of lung cancer, and the risk increases with the amount of second-hand smoke exposure and the duration of exposure.

The International Agency for Research on Cancer (IARC) concluded that non-smokers with a partner who smokes had an estimated 20-30 per cent increased risk of lung cancer.

Second-hand smoke causes immediate adverse effects on the body, which have short-term and long-term impacts.

Short-term impacts Long-term impacts
  • sore throat
  •  itchy eyes
  • coughing
  • headaches
  • nasal irritation
  • shortness of breath
  • lung and other cancers
  • coronary heart disease
  • chronic obstructive pulmonary disease
  • stroke
  • respiratory issues such as asthma
  • poorer general health outcomes
  • premature death


The health risks from passive exposure to second-hand vapour are largely unknown as long-term research studies do not yet exist. To learn more, visit here.

Effects of second-hand smoke on infants and children

Second-hand smoke has adverse impacts on infants and children.

Children are often at greater risk of exposure because they generally do not control their environment and cannot take action to avoid second-hand smoke.

Because their bodies are developing, infants and young children are especially vulnerable to the harmful effects of second-hand smoke.

These include:

  • asthma
  • other chronic respiratory symptoms
  •  respiratory tract infections
  • decreased lung function
  • middle ear disease
  • other negative health outcomes.

How to reduce exposure to second-hand smoke

Smoking impacts not only the smoker but also the people around them.

Making the environments where we live, work and play, smoke-free is the most effective way to reduce second-hand smoke exposure.

South Australia has comprehensive legislation to protect the community from exposure to second-hand smoke in most indoor areas and public places, including outdoor dining, public transport waiting areas, playgrounds and cars.

For more information visit the Smoke-free environments section of our website.

You can take other actions to further reduce exposure:

  • Make your car and home smoke-free environments.
  • If you or someone in your family smokes, ask them to change their clothes or have a shower before entering the home.
  • Try quitting smoking or supporting a family member to quit — call the Quitline today or visit the Quitting Smoking section of our website.


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This page was last reviewed in May 2022.