Risk Assessment Prioritization Process for Indoor Air Contaminants
Canadians spend approximately 90% of their time indoors and are exposed to a large number of indoor air contaminants. In many cases, these indoor air contaminants are known to cause or exacerbate health effects, such as asthma, allergies, chronic obstructive pulmonary disease and other respiratory diseases. Some indoor air contaminants are found, or are expected to be found, in Canadian homes at a level that could pose an elevated health risk to Canadians.
Health Canada conducts health risk assessments for indoor air contaminants and develops Residential Indoor Air Quality Guidelines (RIAQG), which are issued as voluntary objectives under the Canadian Environmental Protection Act, 1999 (CEPA). RIAQG summarize the health effects of inhalation exposure to specific indoor air contaminants, provide information on exposure and sources in Canadian residential environments, derive recommended short- and/or long-term exposure limits, and give recommendations on ways to reduce exposure in an effort to keep indoor air levels below these exposure limits. When a recommended exposure limit cannot be derived from the available scientific evidence, a guidance document is developed that focuses on recommendations to control sources or other actions to reduce exposure.
Health Canada also establishes Indoor Air Reference Levels (IARL) which are screening values derived for contaminants for which there is no RIAQG or guidance. Health Canada does not perform new risk assessments to develop an IARL, but rather evaluates assessments from internationally recognized health and environmental organizations, and selects the most appropriate previously-derived reference level for Canadian homes. The IARL represent concentrations that are associated with acceptable levels of risk following long-term exposure, as determined by the organization that performed the risk assessment.
Health Canada's health risk assessments are used as the scientific basis for actions to reduce exposure to indoor contaminants and help protect human health. They are developed to support the needs and activities of provinces, territories, municipalities, and other federal agencies and departments. They are also used for risk management activities, including the development of standards and regulations related to indoor air quality.
Prioritization of indoor air contaminants
Health Canada has developed a process to prioritize contaminants for assessment, to be conducted approximately every three years. It assigns greater priority to contaminants for which there is new information suggesting a health concern due to inhalation exposure at levels that may be found in indoor air. The risk assessment prioritization process has four steps described in Figure 1.
If you would like more information on Health Canada's risk assessment prioritization process for indoor air contaminants or have any questions about indoor air contaminants, please contact us at HC.air.SC@canada.ca.
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