Annual Air Pollutant Statistics
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Type: A =  ambient air monitoring; I = industrial air monitoring
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Ozone (O3) Statistics
AAQC: Ambient Air Quality Criterion
Unit: parts per billion (ppb)
O3 1-hour AAQC: 80 ppb
INS indicates there was insufficient data in the second and/or third quarter to calculate a valid annual mean.
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Nitrogen Dioxide (NO2) Statistics 
Unit: parts per billion (ppb)
AAQC: Ambient Air Quality Criteria
NO2 1-hour AAQC: 200 ppb
NO2 24-hour AAQC: 100 ppb
INS indicates there was insufficient data in any one quarter to calculate a valid annual mean.
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Sulphur Dioxide (SO2) Statistics
Unit: parts per billion (ppb)
AAQC: Ambient Air Quality Criteria
SO2 10 min AAQC: 67 ppb introduced in 2018
SO2 1h AAQC: 250 ppb revised to 40 ppb in 2018
SO2 24h AAQC: 100 ppb (in effect prior to 2018)
SO2 1y AAQC: 20 ppb revised to 4 ppb in 2018
INS indicates there was insufficient data to calculate a valid annual mean.
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Fine Particulate Matter (PM2.5) Statistics
Unit: micrograms per cubic metre (µg/m3)
PM2.5 24h reference level: 30 µg/m3 revised to 28 µg/m3 in 2013, revised to an AAQC of 27 µg/m3 in 2020
PM2.5 annual AAQC: 8.8 µg/m3 introduced in 2020.
INS indicates there was insufficient data in any one quarter to calculate a valid annual mean.
Measurements taken by Synchronized Hybrid Ambient Real-time Particulate (SHARP) 5030. Ontario’s move to new measurement technology in 2013 has resulted in increased PM2.5 annual means; the increases are not an indication that the air quality has changed, but that the measurements are more accurate.
Measurements taken by Tapered Element Oscillating Microbalance (TEOM) sampler operated at 30 degrees Celsius with a Sample Equilibrium System (SES) from 2003 to 2012. SES Dryers installed on TEOMs in 2003. 
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Carbon Monoxide (CO) Statistics
Unit: parts per million (ppm)
AAQC: Ambient Air Quality Criteria
CO 1-hour AAQC: 30 ppm
CO 8-hour AAQC: 13 ppm
INS indicates there was insufficient data to calculate a valid annual mean.
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Total Reduced Sulphur (TRS) Compunds Statistics
Unit: parts per billion (ppb)
INS indicates there was insufficient data to calculate a valid annual mean.
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