What is passive smoking?

  • Passive smoking is breathing in other people’s tobacco smoke (second-hand smoke)
  • It can increase the risk of cancer, heart disease and many other conditions
  • There is no safe level of passive smoking, and it is particularly dangerous for children

What is passive smoking?

Passive smoking means breathing in other people’s tobacco smoke. If a pregnant woman breathes in second-hand smoke, it can also affect the unborn baby.

Second-hand tobacco smoke comes from cigarettes, pipes, cigars and shisha pipes (hookah).

The two types of second-hand smoke are:

Mainstream smoke - smoke that’s breathed out by someone who smokes  

Side-stream smoke - smoke that comes from the lit end of a tobacco product

Passive smoking is dangerous and can cause many of the same diseases as smoking.

If you smoke, the best thing you can do to protect your loved ones and your own health is to stop. Have a read of our tips and support to help you quit smoking for good.


Health risks of passive smoking

There is no safe level of passive smoking.

Tobacco smoke releases over 5000 chemicals and many of these are harmful. Most harmful tobacco smoke is invisible, but it spreads easily and can stay in the air for hours. It can also build up on surfaces and clothes.

Passive smoking puts people at higher risk of smoking-related diseases. It’s clear that second-hand smoke can cause lung cancer, heart disease and stroke. It may also increase the risk of some other types of cancer, and a serious lung condition called chronic obstructive pulmonary disease (COPD).

Coughing, headaches, sore throats and eye and nasal irritation are some of the short-term effects of passive smoking.


Second-hand smoke and pregnancy

When pregnant women breathe in second-hand smoke, it can have serious risks for the baby during pregnancy and after birth. This includes an increased risk of low birth weight and cot death.

But there is no clear link between exposure to second-hand smoke before birth and childhood cancer.

Whether you’re about to become a parent, grandparent, or live with someone whose pregnant, the best thing you can do to protect an unborn baby is to stop smoking completely.


Passive smoking and children

Passive smoking is particularly dangerous for children as their bodies are still developing.

Children and babies exposed to second-hand smoke are at higher risk of:

  • Asthma
  • Bacterial meningitis
  • Cot death
  • Middle ear infection
  • Respiratory infections

And the dangers of smoking around children go beyond just damaging their health through second-hand smoke. There is good evidence that children are significantly more likely to start smoking themselves, if they have family members or live with people who smoke.


How can I protect my child, myself and others from passive smoking?

Most exposure to second-hand smoke happens in the home. Smoke can spread throughout the home from room to room and stay in the air for hours, even if you open the windows.  

The only way to protect your loved ones from second-hand smoke is the keep the environment around them smoke free. The best way of doing this is to stop smoking completely. But we know that this can be hard, so if you aren’t able to stop yet, smoking outside can help reduce exposure.

You should also ask any visitors to smoke outside and never smoke or let anyone else smoke in the car. Second-hand smoke can reach very high levels inside cars, even with the windows open, because it’s a small, enclosed space.

In the UK, since 2016 it has been against the law to smoke in a vehicle with anyone under the age of 18 inside.


Gee IL, Semple S, and Watson A, C. A. Nearly 85% of tobacco smoke is invisible - a confirmation of previous claims. Tob. Control . 22, 429 (2013).

International Agency for Reseach on Cancer. Personal Habit and Indoor Combustion: Second-hand Tobacco Smoke. Vol  100 E (2012).

International Agency for Research on Cancer. Tobacco smoke and involuntary smoking. Vol 83, 1–1413 (2004).

Tobacco Advisory Group of the Royal College of Physicians. Passive Smoking and Children. (2010).

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