The Air Quality Health Index (AQHI) is Environment Canada's 1 to 10+ scale for the short-term health risk of the air you breathe: 1–3 low, 4–6 moderate, 7–10 high, 10+ very high. It combines ozone, fine particles and nitrogen dioxide; forecasts are issued twice a day.
AQHI now
Lethbridge
1
Low health risk
Observed Thu 6:00 AM · Environment and Climate Change Canada
At-risk population: Enjoy your usual outdoor activities.
General population: Ideal air quality for outdoor activities.
The AQHI turns measured ozone, fine particulate matter (PM2.5) and nitrogen dioxide into one number from 1 to 10+. Low (1–3) means ideal conditions for being outdoors; moderate (4–6) means people with heart or breathing problems should watch for symptoms; high (7–10) means at-risk groups should reduce strenuous outdoor activity and everyone else should consider it; very high (10+) means everyone should cut back. Observations update hourly and forecasts are issued twice a day. In Quebec the AQHI covers Montréal, Québec City and Gatineau; elsewhere in the province, the Quebec government's IQA index is the reference.