Toluene in Indoor Air

Toluene is one of a diverse, group of chemicals known as volatile organic compounds (VOCs), which can be released as a gas into indoor air at room temperatures. Most of our exposure to toluene occurs indoors; this is because levels indoors are higher compared to outdoors and because most of our time is spent indoors.

Toluene is commonly added to gasoline, and can enter the home in vehicle exhaust or vapours from stored fuel coming from attached garages or from outside. Toluene is also often used a solvent and can be released from a variety of products found in homes including; paints and other finishes, adhesives, automotive products, and some personal care products. It is also found in tobacco smoke.

What are the health effects of toluene?

The health effects of toluene depend on the level to which you are exposed, for how long you are exposed, and your own personal sensitivity to the chemical. Toluene has been shown to cause eye, nose and throat irritation, headaches, dizziness and feelings of intoxication in laboratory and workplace studies. It has also been linked to neurological effects including reduced scores in tests of short-term memory, attention and concentration, visual scanning, simple physical tasks, as well as negative effects on colour vision and hearing.

Toluene is primarily a concern in industrial workplaces. Levels of toluene in most Canadian homes are far below the recommended limit in Health Canada's Residential Indoor Air Quality Guideline for toluene. So for most homes there is little risk to health from toluene exposure. Toluene may pose a risk in situations where the home is located near or on an industrial-contaminated site, if it results in toluene levels that are much higher than typical indoor home levels.

What can I do to reduce toluene levels in my home?

Although toluene levels in your home likely do not pose a risk to health, the main sources of toluene may also release other contaminants such as benzene or formaldehyde. There are some simple steps to reduce your overall exposure to these chemicals including:

  • Do not allow smoking in your home
  • Do not run cars or other gas powered engines in attached garages, and keep the door between the house and garage closed at all times
  • Properly store any gasoline or other fuels; it is best if you do not store gasoline in your home
  • Use chemical products as directed by label instructions and properly dispose of any leftover products
  • Increase ventilation, by opening windows or doors, when you are using chemical products inside your home

What are Health Canada's recommended levels for toluene

Health Canada's Residential Indoor Air Quality Guideline for toluene recommends maximum exposure limits below which no negative health effects should occur at:

  • Short-term exposure: 4 parts per million (15 mg/m³) based on a 8-hour average
  • Long-term exposure: 0.6 parts per million (2.3 mg/m³) based on a 24-hour average

Levels of toluene in most Canadian homes are far below the guideline established by Health Canada. In studies conducted by Health Canada the average toluene level measured in Canada ranged from 0.0055 mg/m³ to 0.0247 mg/m³, well below the long-term guideline of 2.3 mg/m³. Toluene is not a health concern in most homes.

Measuring toluene in indoor air in a home would only be recommended in exceptional circumstances, generally where a spill of petroleum or toluene-containing products has occurred and may be impacting indoor air quality. Toluene in highly contaminated soil or groundwater may migrate into nearby buildings through cracks and openings in the foundation.

If air sampling for VOCs is conducted in a home, toluene will commonly be found at much higher concentrations than many other VOCs of interest (e.g. benzene), but generally well below the level at which health effects are expected to occur. When interpreting the results of air testing the differing toxicities among individual VOCs must be considered. As a result, measures of total VOC are not generally a good indicator of the actual health risk.

If toluene levels are found to be higher than recommended, you should increase ventilation and attempt to identify and remove the source. Vehicle exhaust and vapours from stored fuel coming form attached garages is a potential source of toluene. Try to remove the sources (e.g. stored fuel, gas powered lawnmowers or blowers, idling cars) and seal any openings between the garage and your home. You may also try to ventilate your garage outside, and establish a pressure gradient so gases flow outside rather than into the home. A high level of toluene may indicate contamination from soil or groundwater.

What are the Residential Indoor Air Quality Guidelines?

The Residential Indoor Air Quality Guidelines are Health Canada's official position on the health risks posed by an indoor air pollutant, based on a review of the best scientific information available. They summarize the known health effects, describe indoor sources and levels, and, provide a recommended exposure level below which health effects are unlikely to occur. The Guidelines are recommendations only and are not an enforceable standard under any regulation. They are meant to serve as a scientific basis for activities to reduce the risk from indoor contaminants. This could include the development of regulations or standards or the production of communication materials aimed at the general public.

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