Passive smoking means breathing in other people's tobacco smoke. Second-hand smoke is a danger to everyone, but children, pregnant women and the partners of people who smoke are most vulnerable. Passive smoking increases the risk of sudden infant death syndrome (SIDS or cot death), middle ear disease, asthma, respiratory illnesses, lung cancer and coronary heart disease.
Passive smoking means breathing in other people’s tobacco smoke. Exhaled smoke is called exhaled mainstream smoke. The smoke drifting from a lit cigarette is called sidestream smoke. The combination of mainstream and sidestream smoke is called second-hand smoke (SHS) or environmental tobacco smoke (ETS).
Second-hand smoke is a common indoor pollutant in the home, making passive smoking a serious health risk for both those who smoke and those who do not. Children are particularly at risk of serious health effects from second-hand smoke.
In Victoria, it is illegal to smoke in cars carrying children who are under 18 years of age.
Irritant effects of passive smoking
Tobacco smoke inside a room tends to hang in mid-air rather than disperse. Hot smoke rises, but tobacco smoke cools rapidly, which stops its upward climb. Since the smoke is heavier than the air, the smoke starts to descend.
A person who smokes heavily indoors causes a permanent low-lying smoke cloud that other householders have no choice but to breathe.
Tobacco smoke contains around 7,000 chemicals, made up of particles and gases, over 50 of which are known to cause cancer. Second-hand smoke has been confirmed as a cause of lung cancer in humans by several leading health authorities.
Compounds such as ammonia, sulphur and formaldehyde irritate the eyes, nose, throat and lungs. These compounds are especially harmful to people with respiratory conditions such as bronchitis or asthma. Exposure to second-hand smoke can either trigger or worsen symptoms.
Health risks of passive smoking – pregnant women and unborn babies
Australian data indicates that about 12 per cent of women smoke during pregnancy. Both smoking and passive smoking can seriously affect the developing fetus.
Health risks for mothers who smoke during pregnancy include:
- Increased risk of miscarriage and stillbirth
- Increased risk of premature birth and low birth weight
- Increased risk of sudden unexpected death in infants (SUDI), which includes sudden infant death syndrome (SIDS) and fatal sleep accidents
- Increased risk of complications during birth.
Health risks of passive smoking – children
Children are especially vulnerable to the damaging effects of second-hand smoke. Some of the many health risks include:
- Passive smoking is a cause of sudden unexpected death in infants (SUDI), which includes sudden infant death syndrome (SIDS) and fatal sleep accidents.
- A child who lives in a smoking household for the first 18 months of their life has an increased risk of developing a range of respiratory illnesses including bronchitis, bronchiolitis and pneumonia. They are also more prone to getting colds, coughs and glue ear (middle ear infections). Their lungs show a reduced ability to function and slower growth.
- A child exposed to second-hand smoke in the home is more likely to develop asthma symptoms, have more asthma attacks and use asthma medications more often and for a longer period.
- School-aged children of people who smoke are more likely to have symptoms such as cough, phlegm, wheeze and breathlessness.
- Children of people who smoke have an increased risk of meningococcal disease, which can sometimes cause death or disability.
Health risks of passive smoking – partners who have never smoked
People who have never smoked who live with people who do smoke are at increased risk of a range of tobacco-related diseases and other health risks, including:
- Passive smoking increases the risk of heart disease. There is consistent evidence that people who do not smoke, who live in a smoky household, have higher risks of coronary heart disease than those who do not.
- Passive smoking makes the blood more ‘sticky’ and likely to clot, thereby leading to increased risk of various health conditions, including heart attack and stroke.
- There is evidence that passive smoking can cause levels of antioxidant vitamins in the blood to reduce.
- Just 30 minutes of exposure to second-hand smoke can affect how your blood vessels regulate blood flow, to a similar degree to that seen in people who smoke.
- Long-term exposure to passive smoking may lead to the development of atherosclerosis (narrowing of the arteries).
- People who do not smoke who suffer long-term exposure to second-hand smoke have a 20 to 30 per cent higher risk of developing lung cancer.
- There is increasing evidence that passive smoking can increase the risk of stroke, nasal sinus cancer, throat cancer, breast cancer, long- and short-term respiratory symptoms, loss of lung function, and chronic obstructive pulmonary disease among people who do not smoke.
- It is estimated that in Australia, in the financial year 2004–05, 113 adults and 28 infants died from diseases caused by second-hand smoke in the home.
Passive smoking – a good reason to quit
The risks of active smoking are well known. If a person who smokes can’t give up for their own health, then the health of their family or other members of their household could be a stronger motivation. There is a wealth of assistance for people who wish to stop smoking. See your doctor for further information and advice, or ring the Quitline on 13 7848.
Reducing the risk of passive smoking
If a person who smokes is unwilling or unable to stop immediately, there are various ways to help protect the health of the people with whom they live. Suggestions include:
- Make your home smoke-free. Limiting your smoking to one or two rooms is not an effective measure – tobacco smoke can easily drift through the rest of the house.
- Make sure that visitors to your house smoke their cigarettes outdoors.
- Make your car smoke-free. The other occupants will still be exposed to tobacco smoke even if the windows are open. In Victoria, it is illegal to smoke in cars carrying children who are under 18 years of age.
- Don’t allow smoking in any enclosed space where people who do not smoke spend time – for example, in the garage, shed, cubby house, boat or caravan.
- Try to avoid taking children to outdoor areas where people are smoking and you can’t easily move away, such as a café courtyard.
- Make sure that all people who look after your children provide a smoke-free environment.
Where to get help
- Your doctor
- Your pharmacist
- Quitline Tel. 13 7848
Things to remember
- In Victoria, it is illegal to smoke in cars carrying children who are under 18 years of age, and in enclosed workplaces.
- If a person who smokes can’t give up for their own health, perhaps the health of their partner or children, or other members of their household, will be a stronger motivation.
- Passive smoking increases the risk of respiratory illnesses in children, including asthma, bronchitis and pneumonia.
- People who have never smoked who live with people who do smoke are at increased risk of a range of tobacco-related diseases including lung cancer, heart disease and stroke.
You might also be interested in:
- Asthma - pregnancy and breastfeeding.
- Asthma and smoking.
- Asthma children and smoking.
- Smoking - effects on your body.
- Smoking tobacco is deadly.
Want to know more?
Go to More information for support groups, related links and references.
This page has been produced in consultation with and approved by:
(Logo links to further information)
The Quit logo - links to further information
Last reviewed: February 2013
Content on this website is provided for education and information purposes only. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your doctor or other registered health professional. Content has been prepared for Victorian residents and wider Australian audiences, and was accurate at the time of publication. Readers should note that, over time, currency and completeness of the information may change. All users are urged to always seek advice from a registered health care professional for diagnosis and answers to their medical questions.
Content on this website is provided for education and information purposes only. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your qualified health professional. Content has been prepared for Victorian residence and wider Australian audiences, and was accurate at the time of publication. Readers should note that over time currency and completeness of the information may change. All users are urged to always seek advice from a qualified health care professional for diagnosis and answers to their medical questions.
For the latest updates and more information, visit www.betterhealth.vic.gov.au
Copyight © 1999/2013 State of Victoria. Reproduced from the Better Health Channel (www.betterhealth.vic.gov.au) at no cost with permission of the Victorian Minister for Health. Unauthorised reproduction and other uses comprised in the copyright are prohibited without permission.