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Secondhand smoke and the people around you

When you smoke, the people around you inhale the smoke you breathe out and the smoke burning from the cigarette. This is called secondhand smoke. It's very harmful.

Quitting is not only the best thing to do for your health – it will protect your loved ones from harmful secondhand smoke.

Secondhand smoke means health risks for the people around you. Even if you don’t smoke near them, they can still breathe in the smoke (and the harmful chemicals it contains) from your hair, skin and clothes. There is no safe level of secondhand smoke. Did you know there are at least 250 chemicals in secondhand smoke that are known to be toxic, including at least 69 that are known to cause cancer?

Children and babies are particularly vulnerable to the effects of secondhand smoke. 

What’s in cigarette smoke?

  • Tar – a sticky brown substance that contains cancer-causing chemicals.

  • Carbon monoxide – a poisonous gas that reduces the amount of oxygen carried by the blood.

  • Nicotine – the addictive drug in tobacco which plays a role in heart disease.

  • 7000 chemicals that can harm the lungs and contribute to disease, including at least 69 known carcinogens. 

Secondhand smoke has a similar make up to the smoke that is directly inhaled by the person smoking. This means the types of health issues associated with active smoking are similar to the types of health issues associated with secondhand smoke. 

Cardiovascular disease appears to be a particular risk to those exposed to secondhand smoke. 

Effects of secondhand smoke on the unborn child

When a pregnant woman breathes in secondhand smoke, chemicals from the smoke can pass through her lungs into the bloodstream. Nicotine, carbon monoxide and other chemicals can cross the placenta affecting her unborn child.

Women exposed to secondhand smoke are more likely to have a preterm birth (a baby carried for less than 37 weeks) as well as a baby with a lower birth weight.

Health effects of secondhand smoke on infants and children

  • Infants exposed to secondhand smoke have about twice the risk for SIDS (Sudden Infant Death Syndrome or cot death) compared with infants living in a smoke free environment.

  • Compared to children of non-smokers, the children of people who smoke have higher rates of lung or airways infections such as bronchitis, bronchiolitis and pneumonia.

  • Asthma is more common among children of people who smoke. Children with asthma exposed to secondhand smoke have a greater risk of getting symptoms earlier in life, and having more symptoms and asthma attacks. They are more likely to use asthma medications more often and for a longer period. 

  • Children of people who smoke have a lowering in lung function, meaning that on average, they cannot breathe in as deeply or breathe out as hard compared to children of non-smokers. Some evidence suggests that this reduced lung function may even persist into adulthood.

  • Children of people who smoke are more likely to contract ear infections and have an increased risk of meningococcal disease, which can sometimes cause death, mental disability, hearing loss, or loss of a limb.

  • Childhood cancers: leukaemia, brain cancer and lymphomas (where both the pregnant mother and the child after birth were exposed to secondhand smoke).

Health effects of secondhand smoke on adults

Secondhand smoke causes the following diseases and conditions in adults:

It has also been linked to:

  • Cancers of the breast, throat, voice-box, nose and cervix

  • Diabetes

  • Disease of the blood vessels

  • short term respiratory symptoms including cough, wheeze, chest tightness and difficulty breathing

  • Long term respiratory symptoms 

  • Development of asthma and worsening of asthma control

  • Chronic obstructive pulmonary disease (COPD).

Secondhand smoke and other health issues

  • Fertility: secondhand smoke can also affect fertility. If your partner smokes it can affect both your fertility and your partner’s fertility. 

  • The home: not only does smoke hang in the air, the chemicals in this smoke sit on clothes and furniture. 

  • Pets: secondhand smoke can affect the health of pets. This includes this risk of several different cancers. 

What to do about secondhand smoke?

The best way to protect your loved ones from secondhand smoke is to quit smoking. The next best way is to have a total smoking ban inside your home, and to change smoke-filled clothing before carrying babies and children.

For tips, talk to one of our Quitline counsellors from the Quitline or request a Quitline callback

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Please note, this information is for general use only.  Please consult your health professional for further advice.

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Last updated February 2024

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