Glossary · Health & indoor air

Indoor air quality (IAQ)

Also called: indoor air pollutants

How clean and healthy the air inside a home is, affected by ventilation, humidity, combustion gases, particles, chemicals and radon.

What it means

Common indoor pollutants include carbon monoxide, fine particles (PM2.5) from cooking, smoking and wildfire smoke, VOCs from products and furnishings, radon, and mould from excess moisture. The main tools are controlling sources, ventilation (exhaust fans, an HRV or ERV) and filtration (see MERV).

Why it matters in an audit

Energy upgrades change how air moves through a house, so a good audit checks indoor air quality risks before and after air sealing.

Typical numbers

Reference values with their sources. Your energy advisor’s report gives the figure for your own house.

What	Value	Source
Health Canada humidity guidance	Keep relative humidity between 30% and 50%	canada.ca ↗

In Canada

Health Canada also recommends at least one certified CO alarm next to sleeping areas and extra ventilation during painting or renovation.

Sources

Learn more here

Related terms

Carbon monoxide (CO) A colourless, odourless gas from incomplete burning of fuel; it reduces the blood's ability to carry oxygen and can kill at high levels.
PM2.5 (fine particulate matter) Fine, inhalable airborne particles 2.5 microns or smaller, from smoke, cooking, candles and outdoor pollution.
VOCs (volatile organic compounds) Chemicals that evaporate into the air from paints, glues, cleaning products, new furniture, flooring and some building materials.
Radon A natural radioactive gas from uranium in soil and rock that can build up in homes; long-term exposure raises the risk of lung cancer.
Mould Fungi that grow on damp surfaces indoors; they can damage materials and affect health, and moisture is always the root cause.
HRV (heat recovery ventilator) A ventilation system that swaps stale indoor air for fresh outdoor air while transferring heat from the outgoing air to the incoming air.
MERV rating A 1-to-16 rating of how well a furnace or air-handler filter catches airborne particles; higher numbers trap smaller particles.
HEPA filter A very fine high-efficiency particulate air filter used in portable air cleaners and vacuums to trap smoke, dust and other small particles.

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