Childhood Asthma/Tobacco Smoke



Fate and Transport

Exposure Pathway

Methods for Monitoring in the Environment

Methods for Measuring Human Exposure

Strategies for Preventing or Controlling Exposure

Respiratory Harmful Effects

Deposition, Absorption, and Metabolism

Dose-Response Relationship

Organ Sites of Toxicity


Risk Assessment/Risk Management Considerations


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Characteristics of Environmental Tobacco Smoke (ETS)

  • Environmental tobacco smoke (ETS) is the smoke present in the air that nonsmokers inhale. It consists of a diluted combination of sidestream tobacco smoke (SS), which is the smoke emitted from the lit end of a cigarette, cigar or pipe, as well as exhaled mainstream smoke (MS), which is the smoke that emerges from the mouth of the smoker. Inhalation of ETS is referred to as ‘passive smoking’ or ‘involuntary smoking’.
    o Sidestream smoke represents the major source for ETS. The exhaled portions of MS and the vapor phase components that diffuse through the wrapper into the surrounding air constitute minor contributors to ETS.

  • ETS, SS and MS are complex mixtures of 3,800 substances, including more than 40 known or suspected carcinogenic compounds. Between 300-400 of the 3,800 compounds in tobacco smoke have been quantitatively measured in SS and MS. ETS consists of solid respirable particulates (mean diameter = .32 ug), semivolatile, and volatile organic compounds (VOCs).

  • For a complete list of specific constituents identified in ETS, please refer to Environmental Tobacco Smoke: Measuring Exposures and Assessing Health Effects available online at

    o Some of the compounds present in the vapor phase of MS and SS include (makes up about 85% of ETS):
    carbon monoxide
    carbon dioxide

    o Some of the compounds present in the particulate phase of SS and MS include:

Note: Some compounds such as nicotine exist in both vapor and particulate phase.

Take-home message:

  • Many of the compounds present in ETS are irritants. Asthmatics have chronically inflamed bronchial passages, and the smoke irritates those passages. The irritating effect of ETS is unique because many asthma episodes are triggered through allergenic effects (i.e., dust mites, pet dander).
  • Children have little control over their indoor environments, thus they are at an increased risk for asthma attacks triggered by the irritating and harmful compounds present in ETS.