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. These harmful chemicals can also cover walls, furniture, clothes, toys and other objects, and are difficult to remove by cleaning and can remain for months or even years.

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. Non-smokers who live with a smoker have:

  • a 25% to 30% greater risk of developing heart disease
  • a 20% to 30% increased risk of developing lung cancer.

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 of health and developmental problems, and are more vulnerable than adults to the effects of second-hand smoke. This is because their lungs are less mature and because they take more breaths every minute.

If they live with someone who regularly smokes inside the home, children 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 exposure to second-hand smoke affects children.

Laws on second-hand smoke

State and territory governments are responsible for smoke-free laws, and it may differ in each jurisdiction. Check your state or territory government's Department of Health website for smoke-free laws where you live.


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