About passive smoking

Passive smoking is when you breathe in the smoke from other people’s cigarettes, cigars or pipes. It is a serious health threat — being exposed to tobacco smoke for just a moment can cause harm. Unborn babies, children and people with breathing problems are most at risk.

What is passive smoking?

Passive smoking is when someone breathes in second-hand tobacco smoke.

Second-hand smoke is made up of:

  • the smoke that smokers breathe out
  • sidestream smoke — the smoke from the end of lit cigarettes and cigars

Second-hand smoke is also known as environmental tobacco smoke.

Is passive smoking ever safe?

There is no safe level of passive smoking.

Studies show that second-hand smoke can harm you even if you’re exposed for just a moment.

If someone smokes indoors, the harmful chemicals in tobacco smoke can stay in the air for hours. You cannot reduce the smoke to acceptable levels, even if you ventilate or filter the air.

Only 100% smoke-free environments can protect you from the effects of passive smoking.

Effects of passive smoking

Second-hand smoke is a serious health threat:

  • For every 8 smokers who die from a smoking-related disease, 1 non-smoker dies from second-hand smoke exposure.
  • Non-smokers who live with a smoker have a 25% to 30% greater risk of developing heart disease.

Second-hand smoke can cause or worsen a range of conditions and diseases including:

Passive smoking is especially risky for:

  • unborn babies
  • children and young people
  • people with breathing problems

Unborn babies

Smoking tobacco or breathing in second-hand smoke when pregnant or breastfeeding can:

  • affect the growth and health of your baby
  • affect how your baby’s lungs develop
  • increase the risk of stillbirth
  • increase the risk of premature birth
  • increase the risk of complications and illness for both you and your baby

Find out more about smoking and pregnancy.


Children are at risk if they’re exposed to second-hand smoke.

If they live with someone who regularly smokes in their home, they breathe in the same amount of nicotine as if they were smoking 60 to 150 cigarettes a year. This amount:

  • is enough to be considered an occasional smoker
  • increases their risk of lung cancer by 20% to 30%
  • doubles the chance of them becoming a smoker later in life

Find out more about how smoking affects children.

Laws on second-hand smoke

State and territory governments are responsible for smoke-free laws.

Date last updated:

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