Nicotine, Secondhand Smoke and Infants
Smoking outside the home still exposes infants to nicotine

March 4, 2004

Although you may not smoke, you may be exposed to the chemicals in tobacco smoke. How? You may breathe in the smoke given off by the burning end of a cigarette or the smoke exhaled from a smoker. This smoke is called secondhand smoke.

Lung cancer and cardiovascular problems in non-smokers have been linked to secondhand smoke. Children exposed to secondhand smoke are more likely to suffer from lung diseases, ear infections and asthma. Many smokers believe that they can protect their children from tobacco smoke if they smoke away from their kids, for example, by smoking outside their homes. A new study from researchers at San Diego State University and the Centers for Disease Control and Prevention suggests that these parents may NOT be offering much protection to their children from secondhand smoke.

The researchers studied 49 households with children less than one year old. These households were divided into three types:

  1. No exposure (non-smoking) control group (17 households): all residents were non-smokers for at least one year; no visitors smoked in the home for 30 days before the study.

  2. Indirect exposure group (17 households): the mother smoked every day; all cigarettes were NOT smoked in the same room or in a car with an infant. In 14 of these 17 households, all cigarette smoking was done outside the house. Most (76%) of the mothers in this group said that their infants were not exposed to tobacco smoke.

  3. Direct exposure group (15 households): the mother smoked every day; at least 20 cigarettes per week must have been inside the home; at least one cigarette per day must have been smoked at home in the same room as the infant.

The amounts of nicotine in the air, dust, on furniture and on the finger of the mothers' index fingers were measured. Urine and hair samples from the babies were also collected and tested for nicotine and continine. (Continine is a chemical the body produces when it breaks down nicotine.)


Higher amounts of nicotine were found in the air, on furniture surfaces and in dust in the homes of the indirect and direct exposure groups than in the homes of the no exposure (non-smoking) group. The nicotine levels in the living rooms and bedrooms of the direct exposure group were many times higher than those in the rooms of the indirect exposure group. (No nicotine was detected on surfaces and in dust in the homes of the no exposure group.)
Infants who lived in households where they were exposed directly to tobacco smoke had higher levels of continine in their urine and higher levels of nicotine in their hair than infants in the indirectly exposed group or the no exposure group. Mothers in both the indirect exposure and direct exposure groups had similar levels of nicotine on their fingers. (No nicotine was found on the fingers of mothers in the homes of the no exposure group.)

Household Contamination by Secondhand Smoke

The results from this study show that secondhand smoke can contaminate a house even if cigarettes are smoked outside. Moreover, nicotine levels in babies who live in houses where people smoke outside are much higher than in babies who live with non-smokers.

Babies who live with smokers may be exposed to contaminated particles from secondhand smoke in several ways. First, infants may inhale the smoke from a cigarette or the exhaled air from a smoker. Even if cigarettes are not smoked near a baby, cigarette fumes may contaminate dust that settles in carpets, on toy and furniture surfaces and on the floor. These objects can remain contaminated for several months! Because babies spend a lot of time crawling on the floor and put toys in the mouths, they are especially at risk to ingest this contaminated dust. Smokers may also contaminate their homes by bringing in clothing exposed to smoke.

Protecting Non-smokers

The data suggest that only a complete ban on smoking will protect a household from secondhand smoke contamination. Even people who tried to protect their babies from secondhand smoke by smoking outside still contaminated their homes with nicotine. As the researchers write:

"...smoking outdoors, in different rooms, or when non-smokers are absent
does not completely protect non-smokers from tobacco smoke."

The researchers propose several steps to reduce the risks of secondhand smoke to non-smokers:

  • Homes, cars and furniture of smokers should be decontaminated.
  • Tenants of apartments and offices and new owners of cars and houses should be told if previous tenants and owners were smokers.

References and further information:

  1. Matt, G.E., Quintana, P.J.E., Hovell, M.F., Bernert, J.T., Song, S., Novianti, N., Juarez, T., Flora, J., Gehrman, C., Garcia, M. and Larson, S. Households contaminated by environmental tobacco smoke: sources of infant exposures. Tobacco Control, 13:29-37, 2004.
  2. Nicotine and the Nervous System - Neuroscience for Kids
  3. Nicotine -- The Danger of "Just One Cigarette" - Neuroscience for Kids
  4. "Alternative" Cigarettes Not Safer Than Regular Cigarettes - Neuroscience for Kids
  5. The Power of Nicotine - Neuroscience for Kids
  6. The World Health Organization (WHO) Fights Tobacco - Neuroscience for Kids
  7. Secondhand Smoke - Canadian Cancer Society
  8. American Lung Association

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