"National average peak ozone concentrations, Canada, 2009 to 2023",,, ,,, Year,Average peak (4th-highest) 8-hour concentration (parts per billion),10th percentile (ppb),90th percentile (ppb) 2009,57.4,48,68.4 2010,59,47.6,70.8 2011,57,47.3,68.3 2012,60,47.9,76.5 2013,56.4,46.8,65.8 2014,54.1,46.3,63.9 2015,58.2,48.1,67.3 2016,56.2,43.8,69.3 2017,56.8,47.4,66.4 2018,59.1,49.1,68 2019,53.5,45.8,62.3 2020,53.9,44.9,64.8 2021,57.7,47,66.5 2022,54,45.9,63.4 2023,59,47.6,70 2020 standard ,62,n/a,n/a Annual trend ,No trend ,n/a,n/a ,,, "Note: n/a = not applicable. The national average peak O3 concentration indicator is based on the annual 4th-highest of the daily maximum 8-hour average concentrations recorded at 169 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) and the Canadian Air and Precipitation Monitoring Network (www.canada.ca/en/environment-climate-change/services/air-pollution/monitoring-networks-data/canadian-air-precipitation.html).,,, Available on the Environmental indicators website (www.canada.ca/environmental-indicators).,,,