Pollutant concentrations for
October 31, 2025, 11:00 am EDT

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Pollutant concentrations for
October 31, 2025, 11:00 am EDT October 31, 2025, 11:00 am EDT
Station O3 (ppb) PM2.5 (µg/m3) NO2 (ppb) SO2 (ppb) CO (ppm)
Barrie 22Barrie graph for O3 2Barrie graph for PM2.5 1.9Barrie graph for NO2    
Belleville 14Belleville graph for O3 0Belleville graph for PM2.5 1.3Belleville graph for NO2    
Brampton 20Brampton graph for O3 3Brampton graph for PM2.5 1.8Brampton graph for NO2    
Brantford 26Brantford graph for O3 2Brantford graph for PM2.5 1Brantford graph for NO2    
Burlington 19Burlington graph for O3 3Burlington graph for PM2.5 6.3Burlington graph for NO2    
Chatham 27Chatham graph for O3 3Chatham graph for PM2.5 3.1Chatham graph for NO2    
Cornwall 15Cornwall graph for O3 0Cornwall graph for PM2.5 2.5Cornwall graph for NO2    
Dorset 24Dorset graph for O3 1Dorset graph for PM2.5      
Grand Bend 33Grand Bend graph for O3 2Grand Bend graph for PM2.5 0.2Grand Bend graph for NO2    
Guelph 24Guelph graph for O3 3Guelph graph for PM2.5 0.6Guelph graph for NO2    
Hamilton Downtown 20Hamilton Downtown graph for O3 3Hamilton Downtown graph for PM2.5 4.4Hamilton Downtown graph for NO2 0.7Hamilton Downtown graph for SO2 0.16Hamilton Downtown graph for CO
Hamilton Mountain 21Hamilton Mountain graph for O3 3Hamilton Mountain graph for PM2.5 1.5Hamilton Mountain graph for NO2 0Hamilton Mountain graph for SO2  
Hamilton West 22Hamilton West graph for O3 3Hamilton West graph for PM2.5 3.7Hamilton West graph for NO2    
Kingston 14Kingston graph for O3 0Kingston graph for PM2.5 1.4Kingston graph for NO2    
Kitchener 23Kitchener graph for O3 3Kitchener graph for PM2.5 1.5Kitchener graph for NO2    
London 22London graph for O3 3London graph for PM2.5 2.8London graph for NO2    
Milton 23Milton graph for O3 4Milton graph for PM2.5 2.7Milton graph for NO2 0.3Milton graph for SO2  
Mississauga 21Mississauga graph for O3 3Mississauga graph for PM2.5 3.4Mississauga graph for NO2    
Newmarket 25Newmarket graph for O3 2Newmarket graph for PM2.5 2Newmarket graph for NO2    
North Bay 17North Bay graph for O3 3North Bay graph for PM2.5 1.7North Bay graph for NO2    
Oakville 23Oakville graph for O3 3Oakville graph for PM2.5 1.8Oakville graph for NO2    
Oshawa 24Oshawa graph for O3 1Oshawa graph for PM2.5 0.9Oshawa graph for NO2    
Ottawa Downtown 13Ottawa Downtown graph for O3 1Ottawa Downtown graph for PM2.5 4Ottawa Downtown graph for NO2    
Parry Sound 22Parry Sound graph for O3 3Parry Sound graph for PM2.5 0.5Parry Sound graph for NO2    
Peterborough 20Peterborough graph for O3 0Peterborough graph for PM2.5 0.8Peterborough graph for NO2    
Port Stanley 21Port Stanley graph for O3 3Port Stanley graph for PM2.5 2.3Port Stanley graph for NO2    
Sarnia 25Sarnia graph for O3 3Sarnia graph for PM2.5 2.2Sarnia graph for NO2 0.2Sarnia graph for SO2  
Sault Ste. Marie 28Sault Ste. Marie graph for O3 3Sault Ste. Marie graph for PM2.5 2.3Sault Ste. Marie graph for NO2 0Sault Ste. Marie graph for SO2  
St. Catharines 21St. Catharines graph for O3 3St. Catharines graph for PM2.5 4.9St. Catharines graph for NO2    
Sudbury 23Sudbury graph for O3 3Sudbury graph for PM2.5 0Sudbury graph for NO2 0.1Sudbury graph for SO2  
Thunder Bay 14Thunder Bay graph for O3 6Thunder Bay graph for PM2.5 5.8Thunder Bay graph for NO2    
Tiverton 28Tiverton graph for O3 2Tiverton graph for PM2.5      
Toronto Downtown 15Toronto Downtown graph for O3 5Toronto Downtown graph for PM2.5 12.6Toronto Downtown graph for NO2    
Toronto East 20Toronto East graph for O3 2Toronto East graph for PM2.5 5.7Toronto East graph for NO2    
Toronto North 23Toronto North graph for O3 1Toronto North graph for PM2.5 5.4Toronto North graph for NO2 0.1Toronto North graph for SO2  
Toronto West 16Toronto West graph for O3 2Toronto West graph for PM2.5 9.6Toronto West graph for NO2 0Toronto West graph for SO2 0.15Toronto West graph for CO
Windsor Downtown 20Windsor Downtown graph for O3 5Windsor Downtown graph for PM2.5 8.2Windsor Downtown graph for NO2 0Windsor Downtown graph for SO2 0.16Windsor Downtown graph for CO
Windsor West 19Windsor West graph for O3 6Windsor West graph for PM2.5 8.7Windsor West graph for NO2 0Windsor West graph for SO2  

Order by station location (east to west)

Note: 
Ontario 1-hour AAQC for O3 = 80 ppb
Ontario 1-hour AAQC for NO2 = 200 ppb
Ontario 1-hour AAQC for SO2 = 40 ppb
Ontario 1-hour AAQC for CO = 30 ppm

Note: The pollutant concentrations on this web page are based on automatically polled data and have not undergone final verification.

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