Ontario - Air Quality Health Index - Summary

Choose a province or territory

Forecast Regions

This table is a summary of air quality health messages by category
Health Risk	Air Quality Health Index	Health Messages
Health Risk	Air Quality Health Index	At Risk Population*	General Population
Low Risk	1-3	Enjoy your usual outdoor activities.	Ideal air quality for outdoor activities.
Moderate Risk	4-6	Consider reducing or rescheduling strenuous activities outdoors if you are experiencing symptoms.	No need to modify your usual outdoor activities unless you experience symptoms such as coughing and throat irritation.
High Risk	7-10	Reduce or reschedule strenuous activities outdoors. Children and the elderly should also take it easy.	Consider reducing or rescheduling strenuous activities outdoors if you experience symptoms such as coughing and throat irritation.
Very High Risk	Above 10	Avoid strenuous activities outdoors. Children and the elderly should also avoid outdoor physical exertion.	Reduce or reschedule strenuous activities outdoors, especially if you experience symptoms such as coughing and throat irritation.

This table shows a summary of current Air Quality Health Index values and forecast maximums¹
Location and sub-locations	Observed Conditions	Forecast Maximums
Location and sub-locations	Observed Conditions	Monday night	Tuesday	Tuesday night	Wednesday
Barrie	3 Low Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Belleville	3 Low Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Brampton	3 Low Risk	4 Moderate Risk	3 Low Risk	3 Low Risk	3 Low Risk
Brantford	3 Low Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Burlington	4 Moderate Risk	4 Moderate Risk	3 Low Risk	3 Low Risk	3 Low Risk
Chatham	3 Low Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Cornwall	3 Low Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Dorset	3 Low Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Grand Bend	4 Moderate Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Guelph	4 Moderate Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Hamilton	3 Low Risk	4 Moderate Risk	3 Low Risk	3 Low Risk	3 Low Risk
Hamilton Downtown	3 Low Risk	4 Moderate Risk	3 Low Risk	3 Low Risk	3 Low Risk
Hamilton Mountain	4 Moderate Risk	4 Moderate Risk	3 Low Risk	3 Low Risk	3 Low Risk
Hamilton West	3 Low Risk	4 Moderate Risk	3 Low Risk	3 Low Risk	3 Low Risk
Kingston	3 Low Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Kitchener	4 Moderate Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
London	3 Low Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Milton	4 Moderate Risk	4 Moderate Risk	3 Low Risk	3 Low Risk	3 Low Risk
Mississauga	3 Low Risk	4 Moderate Risk	3 Low Risk	3 Low Risk	3 Low Risk
Newmarket	3 Low Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
North Bay	3 Low Risk	3 Low Risk	2 Low Risk	2 Low Risk	2 Low Risk
Oakville	3 Low Risk	4 Moderate Risk	3 Low Risk	3 Low Risk	3 Low Risk
Oshawa	3 Low Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Ottawa	3 Low Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Parry Sound	3 Low Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Peterborough	3 Low Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Port Stanley	1 Low Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Sarnia	4 Moderate Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Sault Ste. Marie	3 Low Risk	3 Low Risk	2 Low Risk	2 Low Risk	2 Low Risk
St. Catharines	3 Low Risk	4 Moderate Risk	3 Low Risk	3 Low Risk	3 Low Risk
Sudbury	3 Low Risk	3 Low Risk	2 Low Risk	2 Low Risk	2 Low Risk
Thunder Bay	2 Low Risk	2 Low Risk	2 Low Risk	2 Low Risk	2 Low Risk
Tiverton	4 Moderate Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Toronto	4 Moderate Risk	4 Moderate Risk	3 Low Risk	3 Low Risk	3 Low Risk
Toronto Downtown	4 Moderate Risk	4 Moderate Risk	3 Low Risk	3 Low Risk	3 Low Risk
Toronto East	3 Low Risk	4 Moderate Risk	3 Low Risk	3 Low Risk	3 Low Risk
Toronto North	3 Low Risk	4 Moderate Risk	3 Low Risk	3 Low Risk	3 Low Risk
Toronto West	4 Moderate Risk	4 Moderate Risk	3 Low Risk	3 Low Risk	3 Low Risk
Windsor	3 Low Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Windsor Downtown	3 Low Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk
Windsor West	3 Low Risk	4 Moderate Risk	2 Low Risk	2 Low Risk	2 Low Risk

1. Forecast issued at: 5:00 PM EDT Monday 4 May 2026