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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

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.

It can even be more toxic than the smoke inhaled directly from a cigarette, as lower temperatures allow more toxins to be present.

Evidence suggests that side-stream smoke may become more harmful as it changes from fresh to stale.

Second-hand smoke causes immediate adverse effects on the cardiovascular system, 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


For non-smokers with a partner who smokes, the risk of developing lung cancer from second-hand smoke is estimated to be 20-30 per cent.


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.

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.


This page was last reviewed in November 2021