Passive smoking

Passive smoking means breathing in other people’s tobacco smoke. The smoke drifting from a lit cigarette, plus the smoke breathed out by a smoker, is called second-hand smoke or environmental tobacco smoke. Second-hand smoke is a serious health risk for both people who smoke and those who do not, and children are especially vulnerable.

Many places restrict smoking in and around schools, childcare centres, hospitals, public transport, outdoor dining areas and other public spaces. Local rules vary, so check the regulations that apply where you live.

How tobacco smoke behaves indoors#

Tobacco smoke inside a room tends to hang in the air rather than disperse. Hot smoke rises, but tobacco smoke cools rapidly, which stops it rising. Because the smoke is then heavier than the surrounding air, it starts to sink. Someone who smokes heavily indoors creates a low-lying smoke cloud that other people in the home have little choice but to breathe.

Tobacco smoke contains around 7,000 chemicals, made up of particles and gases, more than 70 of which are known to cause cancer. Chemicals in second-hand smoke, such as ammonia, sulphur and formaldehyde, damage the eyes, nose, throat and lungs. They are especially harmful to people with lung conditions, and exposure to second-hand smoke can trigger or worsen their symptoms.

Pregnancy and unborn babies#

When a pregnant woman breathes in tobacco smoke, her unborn baby is exposed to the chemicals in it too. Both active smoking and passive smoking can seriously affect a developing baby.

When a non-smoking pregnant woman is exposed to second-hand smoke at home, for example if her partner smokes, it increases the risk of problems such as low birth weight. Active smoking by men can also damage their sperm.

Some health problems may be caused by a non-smoking mother breathing in second-hand smoke, by sperm damage from the father’s tobacco use, or by both. Risks linked to smoking and passive smoking in pregnancy include ectopic pregnancy, miscarriage and stillbirth, premature birth and low birth weight, complications during birth, lower fertility, birth defects such as cleft lip or palate, and some childhood cancers. They also include sudden unexpected death in infancy (SUDI), which includes sudden infant death syndrome (SIDS) and fatal sleep accidents.

Health risks for children#

Children are especially vulnerable to the harmful effects of second-hand smoke. A child who lives in a smoking household during the first 18 months of life has an increased risk of lung illnesses, including bronchitis, bronchiolitis and pneumonia. Their lungs tend to be weaker and may not grow to their full potential.

A child exposed to second-hand smoke at home is more likely to develop asthma symptoms, to have them more often and for longer, and to need asthma medication. School-aged children of people who smoke are more likely to have a cough, phlegm, wheeze and breathlessness. They are also more prone to glue ear (middle ear infections) and have an increased risk of meningococcal disease, which can sometimes cause disability or death.

Health risks for adults who have never smoked#

People who have never smoked but live with people who do are at increased risk of a range of tobacco-related diseases. Second-hand smoke affects the blood vessels in several ways: it makes the blood more likely to clot, and passive smoking is associated with lower levels of antioxidant vitamins in the blood.

Just 30 minutes of passive smoking can affect how your blood vessels regulate blood flow, to a degree similar to that seen in people who smoke. Over a long period, passive smoking may contribute to atherosclerosis (narrowing of the arteries by fatty deposits) and to heart disease and stroke.

Second-hand smoke is a confirmed cause of lung cancer. People exposed to it over a long time have a 20 to 30 per cent higher risk of developing lung cancer. There is also growing evidence that passive smoking may increase the risk of cancers of the nasal sinus, mouth, throat and larynx, as well as long- and short-term respiratory symptoms, loss of lung function and chronic obstructive pulmonary disease.

Reasons to quit#

When you stop smoking, you do something good not only for your own health but for the people you love. You protect your partner, children and other household members from the harms of second-hand smoke. You are also likely to have more energy and time to spend with your family, and to save money.

You are also your child’s first role model. Parents who stop smoking reduce the chance that their children will take up smoking later in life. Thinking about your own reasons to quit can help you stay motivated.

Protecting others if you still smoke#

If you smoke but are unwilling or unable to stop right away, you can still take steps to protect the people you live with:

• Make your home completely smoke-free. Always smoke outdoors, and shut windows and doors so smoke does not drift inside.
• Remember that limiting smoking to one or two rooms will not protect your family, because smoke easily drifts through the rest of the home.
• Ask visitors to smoke outdoors, including those using a water pipe (shisha) as well as cigarettes.
• Make your car completely smoke-free. Opening the windows does not protect other passengers.
• Do not allow smoking in any enclosed space where non-smokers spend time, such as a garage, shed or boat.
• Try to avoid taking children to outdoor areas where people are smoking and you cannot easily move away.
• Make sure everyone who looks after your children provides a smoke-free environment.

Help is available if you want to stop smoking. Talk to your doctor or pharmacist, or contact a local quit-smoking service to find out about your options.

Key points#

• Second-hand smoke is a serious health risk for both people who smoke and those who do not.
• Children are particularly at risk of serious health effects from second-hand smoke, including SUDI, bronchiolitis, pneumonia and asthma.
• Exposure to second-hand smoke can trigger or worsen symptoms, especially in people with lung conditions.
• Making your home and car completely smoke-free is the best way to protect others.

Where to get help#