Health effects of second-hand smoke

Around 350 New Zealanders die each year because of exposure to other people’s tobacco smoke. This makes second-hand smoke the leading environmental cause of death in this country.

Non-smokers who breathe second-hand smoke suffer many of the same diseases as regular smokers. Heart disease as well as lung and nasal sinus cancers have been associated with second-hand smoke exposure. Even short-term exposure to second-hand smoke does real damage. For example, if you spend just 30 minutes in a smoky venue, you risk damaging the lining of your arteries, your blood will become more sticky and you will increase your risk of a heart attack or stroke.

Exposure of non-smoking women to second-hand smoke during pregnancy can reduce foetal growth. Second-hand smoke also causes immediate effects such as eye and nasal irritation, headache, sore throat, dizziness, nausea, cough, and respiratory problems.

The small lungs and lighter weight of young children make them particularly vulnerable to the harmful effects of second-hand smoke. Their exposure is linked to:

• middle ear infections (including glue ear)
• lower respiratory illnesses (including croup, bronchitis, bronchiolitis and pneumonia)
• the onset of asthma and worsening of asthmatic symptoms
• reduced lung growth
• sudden infant death syndrome (SIDS, or cot death)
• meningococcal disease.

There is also some evidence that second-hand smoke has an effect on children’s learning development and behaviour.

Short term effects

Even short periods of exposure to second-hand smoke can affect your health.

After 5 minutes – stiffened aorta

Exposure to second-hand smoke stiffens the aorta as much as smoking a cigarette does, making it harder for the heart to pump blood around the body.

After 20 minutes – sticky blood

Exposure to second-hand smoke activates blood platelets which normally help the blood to clot and stop bleeding from a wound. If the platelets are activated while still in the bloodstream, the resulting sticky blood still has to move round the body. Sticky blood increases the likelihood of a blood clot forming, blocking a heart or brain artery, and causing a heart attack or stroke. Sticky blood also damages the artery lining, which can lead to cholesterol build-up and narrowing of arteries. This can cause coronary heart disease, chest pains and heart attacks.

After 30 minutes – arteries affected

Non-smokers usually have arteries that can dilate and boost blood flow to the heart more efficiently than a smoker’s arteries. But exposure to second-hand smoke compromises that advantage after 30 minutes, to the same degree as for a pack-a-day smoker.

Also, after 30 minutes exposure to second-hand smoke, the body’s natural anti-oxidant defences, which help non-smokers manage LDL (bad) cholesterol, are depressed for several hours. Fatty deposits can then build up on the artery walls, increasing the risk of heart attack or stroke.

After 120 minutes – heartbeat affected

As well as causing a faster and irregular heartbeat, second-hand smoke reduces the small random variations in the heartbeat rhythm known as “heart rate variability”. This in turn can cause arrhythmia – large variations in heartbeat – that can cause heart attack or death.