"National average peak nitrogen dioxide concentrations, Canada, 2009 to 2023",,, ,,, Year,Average peak (98th percentile) 1-hour concentration (parts per billion),10th percentile (parts per billion),90th percentile (parts per billion) 2009,42.3,27,55 2010,39.2,25.1,53 2011,38.5,22,52.9 2012,35.5,22.4,47 2013,36.8,22.8,49 2014,38.1,23.6,51.5 2015,36.6,21.6,47.6 2016,34.3,22.4,46.4 2017,35.2,20.5,46.9 2018,36.2,22,47.1 2019,36.5,21.9,47.9 2020,32.8,20.9,43.8 2021,32.6,19.3,44.5 2022,33.7,19.6,46.8 2023,31.9,19.5,45.6 2020 standard,60,n/a,n/a Annual trend,-0.55,n/a,n/a ,,, "Note: n/a = not applicable. The national average peak NO2 concentration indicator is based on the annual 98th percentile of the daily maximum 1-hour average concentrations recorded at 128 monitoring stations across Canada. The comparison to the Canadian Ambient Air Quality Standard is provided for illustrative purposes only. A statistically significant trend is reported when the Mann-Kendall test indicates the presence of a trend at the 95% confidence level. For more information, consult the Methods section (www.canada.ca/en/environment-climate-change/services/environmental-indicators/air-quality.html#Methods).",,, Source: Environment and Climate Change Canada (2025) National Air Pollution Surveillance (NAPS) Program - Open Government Portal (https://open.canada.ca/data/en/dataset/1b36a356-defd-4813-acea-47bc3abd859b).,,, Available on the Environmental indicators website (www.canada.ca/environmental-indicators).,,,