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The effects of smoking and second-hand smoke on health

Effects of smoking

Cigarette smoke contains over 7,000 chemical substances, 69 of which are known carcinogens. Inhaled smoke circulates in the human body and reaches nearly every organ, affecting both the health and well-being of smokers. The smoke also affects the health of non-smokers exposed to it.

Other tobacco products, such as cigars and cigarillos, or the use of a water pipe are not safer alternatives to cigarettes because they also present major health risks.

Electronic cigarettes are a special case. Their long-term health effects, for both users and people who are regularly exposed to the vapours (aerosols), are still unclear. It would seem, however, that electronic cigarettes also present significant health risks. There are many varieties of electronic cigarettes, and their manufacture in Canada has not yet been regulated.


Nicotine is naturally present in tobacco and added to some electronic cigarettes. Nicotine is the root cause of addiction to and physical dependence on tobacco products. You can become dependent quickly, sometimes even before you become a daily smoker. Smoking 1 to 5 cigarettes a week can be enough for a person to become addicted. Nicotine dependence is comparable to heroin or cocaine addiction.

The brain actively develops during gestation and adolescence. As such, the nicotine to which a pregnant woman is exposed adversely affects the brain of a developing fetus. The development of an adolescent’s brain is also adversely affected if exposed to nicotine. The negative consequences associated with nicotine are not necessarily evident at birth or in adolescence but rather in the long term.

Effects on health and well-being

The short-term effects of smoking include:

  • Bad breath
  • Fatigue and a decrease in energy
  • Reduction in the senses of taste and smell
  • Coughing
  • Shortness of breath

Smokers are also at risk of experiencing several health problems, including:

  • Problems affecting the heart and blood vessels
  • Respiratory or lung problems, such as asthma or excessive coughing
  • Certain types of cancers, including lung cancer
  • Fertility problems
  • In women: menstrual problems
  • In men: erectile problems

Lower life expectancy

At least half of smokers will die due to smoking. Their life expectancy is reduced by at least 10 years compared to those who have never smoked. Smoking only 1 to 4 cigarettes a day is enough to increase the risk of dying prematurely.

Effects of second-hand smoke

Non-smokers can also be exposed to the chemical substances in smoke when in the presence of smokers. This is known as “exposure to second-hand smoke”.

Second-hand smoke can affect the health and well-being of people who are exposed to it, whether they smoke or not. These people are at higher risk of developing health issues such as:

  • Heart problems
  • Respiratory or lung problems, such as asthma or excessive coughing
  • Lung cancer

Second-hand smoke is one of the most dangerous environmental contaminants. All exposure to second-hand smoke is dangerous – even inhaling a small amount of second-hand smoke can be harmful to one’s health.

Protection and prevention

Quitting smoking

Quitting smoking has many health benefits for people of all ages, some of which happen right from the first minutes after quitting. To learn more, read Health benefits of quitting smoking.

Protection from second-hand smoke

The only way to protect yourself from second-hand smoke is to frequent smoke-free areas. Opening a window, using the range hood, a fan or an air filter are not enough to protect you from indoor second-hand smoke. Even outdoors, second-hand smoke can sometimes be a problem depending on the number of smokers, wind speed, outdoor temperature and the layout of the place.

In Québec, the Tobacco control Act prohibits smoking in many public places, such as:

  • Hospitals
  • Workplaces
  • Schools and daycare centres
  • Restaurants and bars, as well as their terraces
  • Some outdoor areas, such as children’s playgrounds

People at risk

Everyone is at risk of being affected by smoking or second-hand smoke. However, some people are more likely to be affected by second-hand smoke. They include:

Pregnant women

Smoking and exposure to second-hand smoke are major causes of health problems in pregnant women.

Pregnant women who smoke are at high risk of:

  • Ectopic pregnancy (pregnancy in the Fallopian tube)
  • Placenta previa (placenta lying low in the uterus) or rupture of the placenta
  • Premature birth
  • Giving birth to a low-weight or stillborn baby, or one with defects

Pregnant women exposed to second-hand smoke are also at risk of experiencing problems with the birth of their child, including:

  • Premature birth
  • Giving birth to a low-weight or stillborn baby

If you are pregnant, you must avoid smoking or being exposed to second-hand smoke. To find resources to help you quit smoking, see Health Benefits of Quitting Smoking.

Babies and children

Being in close proximity to family members and others who smoke and exposure to second-hand smoke are major causes of health problems in fetuses, babies and children.

Babies and young children are particularly sensitive to second-hand smoke because their lungs are not yet completely developed. Children breathe faster than adults, so they are also more exposed to the chemical substances contained in second-hand smoke.

Babies and children exposed to second-hand smoke are more at risk of suffering from:

  • Coughing
  • Asthma
  • Lung problems
  • Various infections:
    • Pneumonia
    • Bronchitis
    • Otitis, etc.

The risk of sudden infant death syndrome increases if babies are exposed to second-hand smoke during pregnancy.

Last update: May 24, 2017


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