Reference

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.

N95 is a NIOSH (US) filtering facepiece rating; FFP2 and FFP3 come from Europe's EN 149. The filtration numbers look close — 95%, 94%, 99% — but the test methods, leakage requirements, and legal acceptance differ. Here is the honest conversion logic, the markings that prove authenticity, and what each jurisdiction accepts.