Passive smoking

Disclaimer: This fact sheet is for education purposes only. Please consult with your doctor or other health professional to make sure this information is right for your child.

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What is passive smoking?

Passive smoking is breathing in smoke from other people’s cigarettes, cigars or pipes. Smoke that is breathed out by a smoker is called mainstream smoke. The smoke drifting from the burning end of a cigarette is called sidestream smoke. Second Hand Smoke (SHS) also known as Environmental Tobacco Smoke (ETS) is a combination of mainstream and sidestream smoke with each contributing to about half of the smoke generated. Smoking parents are the most common source of ETS exposure for children.

Sidestream smoke stays in a room longer and contains many cancer causing substances, more than mainstream smoke. As we spend more and more time indoors, SHS is a serious but preventable health hazard. Children in particular are at risk of harmful effects from passive smoking.

What is the health risk for unborn babies?

Smoking during pregnancy is harmful to the developing baby. When a pregnant woman breathes in tobacco smoke, harmful substances absorbed into the mother’s bloodstream can cross the placenta and affect her unborn baby. The placenta does not filter out the many harmful substances in tobacco smoke. Smoking in pregnancy also reduces blood flow through the placenta, which can reduce the amount of oxygen, and nutrients the baby receives.

Exposure to tobacco smoke during pregnancy can greatly increase the risk of miscarriage, stillbirth, prematurity, low birth weight, childhood malformations and sudden infant death syndrome. Also it has harmful effects on the developing lung and immune system resulting in decreased lung function at birth and increased allergic and asthmatic response in childhood. 

What is the health risk for children?

Children exposed to SHS are at risk of sudden infant death syndrome and are more likely to develop a range of illnesses including asthma, croup, bronchitis, bronchiolitis, pneumonia and middle ear infections, compared to children living in smoke-free environments.

Impaired learning, slower growth and changes in behavior have been linked with children’s exposure to passive smoke.

Both asthma and respiratory infections (characterised by wheezing, breathlessness, cough and phlegm) are increased in children who are exposed to SHS. Children of smoking parents are about twice as likely to have symptoms of asthma before they are five years old. Tobacco smoke also triggers asthma attacks and makes a child's asthma more severe than it would otherwise be. Many environmental factors contribute to asthma and passive smoking is one that you can avoid.

What are the main sources of SHS for children?

Parents, family and friends who smoke in enclosed areas such as cars and homes are the main source of SHS for children. The harmful effects on children increase with the number of parents or other household members who smoke.

A new law was introduced in NSW in 2009, on SHS exposure. The law states that if an adult smokes in a car with a child under 16 years old, this will result in a $250 fine.

Smoking outside, away from your child is better but the smell of the smoke is still on your hair, skin and clothes when you return and can still affect your child. Leaving your child inside unattended while smoking outside is also a safety risk as unsupervised children are more at risk of injury.

What you can do to protect your child?

Quitting smoking is the best way to protect your children.

Ask for help from people experienced in giving up smoking (Quitline counsellors, doctors or chemists). This is very important for women who are pregnant or planning pregnancy so that safe options are recommended and made available to them.

As children from smoking families are more likely to take up smoking themselves, parents who quit smoking provide a positive role model for them.

If you are not able to quit, you can still reduce the risk to your children.

1. Choose not to smoke in the car or home or any other enclosed space where children spend time.

2. When visiting friends or leaving your child in the care of another person, make sure that the environment is smoke–free.

3. Ask friends and family who smoke to  not smoke around your children.

4. Remember that opening a window in your home or car does not eliminate exposure to SHS

For more information on how to quit smoking, please visit:


  • Passive smoke in any form is harmful to children.
  • You can choose not to smoke in front of children, especially in enclosed areas such as the car and home. Ask others to do the same.
  • There is support available through the Quitline on 131 848 or  or a, doctor, asthma educator or chemist.
  • Every child has the right to grow up in a ‘smoke free environment'. 
The Children's Hospital at Westmead
Sydney Children's Hospital, Randwick
Hunter New England Kids Health

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