Indoor Air Reference Levels

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Indoor Air Reference Levels

Many volatile organic compounds (VOCs) are present in the indoor air of homes and other buildings in Canada, some of which may pose a risk to human health at certain concentrations. Health Canada has developed exposure limits for a small number of VOCs which were prioritized because they were identified by stakeholders and partners, or are found in indoor air in homes and other buildings in Canada, and have the potential to cause adverse health effects. To assist public health professionals who may need to assess the possible risk from exposure to other VOCs potentially found in indoor air, Health Canada has identified screening values called Indoor Air Reference Levels (IARLs). IARLs are selected for VOCs that have not been addressed by Health Canada's Residential Indoor Air Quality Guidelines.
To identify IARLs, Health Canada evaluated assessments developed by internationally recognized health and environmental organizations. Health Canada did not perform new risk assessments for the IARLs, but rather selected the most relevant reference level derived by other organizations. The IARLs listed below represent concentrations that are associated with acceptable levels of risk after long-term exposure (over several months or years) in non-occupational scenarios for each specific VOC, as determined by the organization that performed the risk assessment.

Summary of Indoor Air Reference Levels

The IARL selected for each VOC is listed in Table 1. The table also lists the organization from which each IARL was selected. The listed critical effects are the health endpoint used as the basis of the IARL, which is typically the most sensitive effect (i.e. occurs at the lowest concentration) that is considered relevant to humans.

Table 1. Indoor Air Reference Levels
VOC CAS RN IARL
(µg/m3)
Critical effect Reference IARL Date
Cancer Non-Cancer
1,1- Dichloroethylene 75-35-4 0.06 Kidney tumours n/a OEHHA (2017) 2023
trans-1,2-Dichloroethylene 156-60-5 40 n/a Immunotoxicity US EPA (2020) 2023
1,3-Butadiene 106-99-0 1.7 Leukemia n/a EC/HC (2000) 2017
1,4-Dichlorobenzene 106-46-7 60 n/a Nasal lesions ATSDR (2006) 2017
1,4-Dioxane 123-91-1 2 Tumours at multiple sites n/a US EPA (2013) 2023
2-Butoxyethanol 111-76-2 82 n/a Nasal lesions OEHHA (2018) 2023 (updated)
2-Ethoxyethanol 110-80-5 70 n/a Reproductive toxicity and hematotoxicity OEHHA (2000)Footnote 1 2017
2-Ethylhexanol 104-76-7 0.4 n/a Nasal lesions US EPA (2019) 2023
3-Chloropropene 107-05-1 1 n/a Neurotoxicity US EPA (1991) 2017
Acetone 67-64-1 70 000 n/a Developmental toxicity VCCEP (2003) 2017
Ammonia 7664-41-7 500 n/a Respiratory symptoms, lung function US EPA (2016a) 2023
Aniline 62-53-3 1 n/a Spleen toxicity US EPA (1990a) 2017
Carbon tetrachloride 56-23-5 1.7 Adrenal gland tumours n/a US EPA (2010) 2017
Chloroform 67-66-3 300 n/a Liver and kidney toxicity OEHHA (2000)Footnote 1 2017
Cyclohexane 110-82-7 6000 n/a Developmental toxicity US EPA (2003a) 2017
Dichloromethane 75-09-2 600 n/a Liver toxicity US EPA (2011a) 2017
Epichlorohydrin 106-89-8 1 n/a Nasal lesions US EPA (1994) 2017
Ethylbenzene 100-41-4 2000 n/a Kidney, pituitary gland, and liver toxicity OEHHA (2000)Footnote 1 2017
Ethylene oxide 75-21-8 0.002 Lymphoid and breast cancer n/a US EPA (2016b) 2023 (updated)
Isopropyl alcohol 67-63-0 7000 n/a Kidney lesions OEHHA (2000)Footnote 1 2017
Isopropylbenzene 98-82-8 400 n/a Kidney toxicity US EPA (1997) 2017
Methyl ethyl ketone 78-93-3 5000 n/a Developmental toxicity US EPA (2003b) 2017
Methyl isobutyl ketone 108-10-1 3000 n/a Developmental toxicity US EPA (2003c) 2017
Propionaldehyde 123-38-6 8 n/a Nasal lesions US EPA (2008) 2017
n-Propylbromide 106-94-5 1.7 - Neurotoxicity OEHHA (2022) 2023
Propylene oxide 75-56-9 2.7 Nasal tumours n/a US EPA (1990b) 2017
Styrene 100-42-5 850 n/a Neurotoxicity ATSDR (2010) 2017
Tetrachloroethylene 127-18-4 40 n/a Neurotoxicity US EPA (2012), ATSDR (2014) 2017
Toluene diisocyanate 26471-62-5 0.008 n/a Altered lung function OEHHA (2016) 2023 (updated)
Trichloroethylene 79-01-6 2 Kidney tumours, Non-Hodgkins lymphoma, liver tumours Thymus and cardiac toxicity US EPA (2011b) 2023
Vinyl Chloride 75-01-4 1.1 Liver tumours n/a US EPA (2000) 2023
Footnote 1

Refers to the actual date of assessment. Toxicological reference value information was summarized from OEHHA (2015), OEHHA (2014), OEHHA (2011) and OEHHA (2008).

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2018-02-05