Reference

CSA Z94.4 is Canada's respirator standard — a selection, use, and care program built on NIOSH-certified equipment. This guide covers the 2018 edition, the two-year fit-testing cycle, provincial enforcement from WorkSafeBC to Ontario, wildfire-smoke selection against the AQHI, and a worked example for a silica-exposed BC crew.

Canada reports air quality on the AQHI, a 1-10+ health index built from three pollutants; the US reports the 0-500 AQI keyed to the worst single pollutant. There is no exact conversion, but wildfire smoke drives both with PM2.5, so the bands line up in practice. This guide maps the scales, decodes the bands, and sets N95 thresholds.