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The Harmful Effects of Second-hand Smoke

Last Updated: February 1, 2022
HealthLinkBC File Number: 30a
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What is second-hand smoke?

Second-hand smoke is a mix of smoke from a burning cigarette, pipe, or cigar, plus the smoke exhaled by the person smoking. This smoke is harmful to the health of both the person who smokes and those who are nearby, especially children. There are ways to reduce the risks, such as by making your home smoke-free.

How harmful is second-hand smoke?

Second-hand smoke is poisonous. It has over 7,000 chemicals, hundreds of which are toxic and at least 70 that can cause cancer.

There is no risk-free level of exposure to tobacco smoke.

How does second-hand smoke harm your health?

Regular exposure to second-hand smoke can cause harm. The risk and severity of the harm depends on the length of exposure and amount of smoke you are exposed to.

For some people, even low levels of exposure can cause physical reactions. These reactions include increased heart rate, less oxygen to the heart and constricted blood vessels that increase blood pressure and make the heart work harder.

In the long term, people exposed to second-hand smoke have a greater risk of suffering from:

  • Breathing problems, such as increased coughing, wheezing, pneumonia and asthma
  • Heart disease
  • Stroke
  • Nasal sinus cancer
  • Lung cancer
  • Emphysema

Pregnant women exposed to second-hand smoke can have a greater risk of miscarriages, premature birth and babies with low birth weight.

How does second-hand smoke harm babies and children?

Children are at higher risk of getting sick from second-hand smoke because their lungs are still developing.

Second-hand smoke is harmful to babies and children in the following ways:

  • Babies who breathe second-hand smoke have a greater chance of dying from Sudden Infant Death Syndrome (SIDS). For more information, see HealthLinkBC File #46 Sleep Related Infant Death
  • Children exposed to second-hand smoke have a greater risk of getting lung infections such as bronchitis and pneumonia. They also suffer more from chronic coughing, wheezing and breathing problems
  • Second-hand smoke can cause fluid to build up in the middle ear which can cause an ear infection
  • Children are more likely to get asthma when exposed to second-hand smoke. Second-hand smoke is harmful to children with existing chronic lung conditions and asthma because it makes the health conditions worse

How can I prevent exposure to second-hand smoke?

To protect your family from second-hand smoke, make your home and car smoke-free. If you smoke, make a plan to quit. See that no one smokes near your child.

Encourage family and friends to create a smoke-free environment. For tips on creating a smoke-free home, visit Health Canada at www.canada.ca/en/health-canada/services/smoking-tobacco/avoid-second-hand-smoke/second-hand-smoke.html

Air purifiers and ventilation systems cannot remove all the poisons, toxins, gases and particles found in second-hand smoke. This means that you will still be exposed to second-hand smoke.

Smoke from a cigarette can stay in a room for hours even with an open window. Many of the toxic chemicals remain in the air and the carpets, curtains, furniture and clothes. Residue from tobacco smoke, also known as third-hand smoke, is especially dangerous for children and for pets. Children tend to crawl around and put things in their mouths that may have third-hand smoke residue on them. The only way to protect them from third-hand smoke is to keep your home smoke-free.

Are there any laws to protect against second-hand smoke exposure?

It is against the law to smoke or vape:

  • In a motor vehicle with anyone under the age of 16 years
  • In the common area of apartment buildings, condominiums and transit shelters
  • On school property at any time
  • Inside or within 6 meters of a doorway, window or air intake of a public building or workplace. Work vehicles are considered workplaces and are to be smoke and vape-free

Your community may have additional rules that make parks, playgrounds and other public places smoke and vape-free or have smoke-free buffer zones that are bigger than 6 metres.

What about vaping?

Research has found that second-hand aerosol (vapour) is not harmless. The aerosol contains nicotine as well as potentially harmful substances such as heavy metals and tobacco-specific nitrosamines. Exposure to second-hand aerosol may lead to more frequent asthma attacks among those with asthma and may have additional health harms that are not yet known.

For More Information

For more information, visit:

Stop Smoking Help

Getting help can make quitting easier. People who make a plan and combine nicotine replacement therapy with quit coaching generally are more successful in their quit attempts.

For more information, see HealthLinkBC File #30c Quitting Smoking

  • QuitNow– Free help to quit tobacco or vaping by phone or website. Visit www.quitnow.ca or call 1-877- 455-2233. Translation services are available
  • The PharmaCare BC Smoking Cessation Program:
    • Covers 100% of the cost of nicotine replacement therapy (NRT) products (for example, patches to help manage cravings
    • Contributes to the cost of smoking cessation prescription medications
    • Eligible BC residents can get NRT from a local pharmacy. Speak to a doctor about prescriptions for quit smoking medications
  • First Nations Health Authority – Respecting Tobacco www.fnha.ca/wellness/wellness-for-first-nations/wellness-streams/respecting-tobacco