Air quality monitoring

Measuring air quality can provide valuable information on how to make spaces safer. A variety of devices are available to measure factors like relative humidity (important for mould), fine particulate matter, a.k.a. PM_2.5 (for many types of air pollution, like wildfire smoke or car exhaust), carbon monoxide, carbon dioxide, and volatile organic compounds (VOCs).

Carbon dioxide (CO₂) concentration is a particularly useful metric. People release CO₂ when they breathe out, so too much CO₂ indoors indicates there isn't enough fresh air replacing stale air.^{Footnote 151} High levels of CO₂ can affect people’s thinking and make them tired, dizzy, or sick.^{Footnote 152} It can also indicate an increased risk of airborne illnesses, because of germs in people’s recently exhaled air.^{Footnote 153} Many experts recommend keeping CO₂ levels under 800 ppm, and aiming closer to outdoor levels (400–600 ppm) for better air quality.^{Footnote 154} Health Canada recommends a long-term limit of no more than 1000 ppm to reduce health risks.^{Footnote 155}

See also: Risk calculators for CO₂ analysis