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The Harmful Effects of Second-hand Smoke

Last Updated: May 1, 2019
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 smokers and non-smokers, including 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 4000 chemicals, including some that can cause cancer.

There is no risk-free level of exposure to tobacco smoke. Smoke affects every organ in the body.

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.

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

For some people, even low levels of exposure can cause problems. Almost immediately, physical reactions can occur that are linked to heart disease and stroke. 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.

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. Do not let anyone smoke 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

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. Children and pets can be exposed to these deposits.

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. Most cars are airtight and the cigarette smoke has no place to escape. Opening a window can force the smoke to be blown directly back at the people in the car
  • 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.

What about vaping?

At this time, there is no evidence that second-hand exposure to vapour causes significant harm to bystanders. Yet non-users will still be exposed to nicotine and other toxins when exposed to a vapour (aerosol cloud).

For More Information

For more information, visit the following:

If you want to quit smoking, speak with your doctor or health care provider. Additional help is available from:

  • QuitNow– Free help to quit smoking, by phone, text or website. Visit or call
    1 877 455-2233. Translation services are available. 
  • The BC Smoking Cessation Program:
    • Covers 100% of the cost of nicotine replacement therapy (NRT) products (specific nicotine gum, lozenges, patches, inhaler), or
    • Contributes to the cost of specific smoking cessation prescription drugs
    • Eligible BC residents can get NRT directly from a pharmacist. Speak to a doctor about prescriptions for quit smoking medications