British Columbia has a network of air monitoring stations that measure ground-level ozone and other air contaminants. This indicator reports on the concentration of ground-level ozone from two reporting periods, 2021-2023 and 2022-2024.  The data are reported as a metric based on three consecutive years of data. These metrics are compared against the Canadian Ambient Air Quality Standards to determine achievement and to define colour-based management levels. CAAQS were established by the Canadian Council of Ministers of the Environment in 2012 as a key element of the Air Quality Management System that collaboratively and comprehensively manages air quality in Canada. The maps and figures below primarily show results from the 2022-2024 period. Detailed findings from 2021-2023 can be found in the PDF version of the indicator available here (PDF 2MB)

• Ground-level ozone is a type of air contaminant. While ozone high up in the Earth’s atmosphere occurs naturally and helps protect us from the sun’s ultraviolet rays, ozone at ground level is a harmful pollutant. It forms when pollution from vehicles, industry, and other sources reacts in sunlight.
• Ground-level ozone can be harmful to humans. Exposure to ground-level ozone (hereafter ozone) can reduce lung function and cause inflammation of airways, which can increase respiratory symptoms and aggravate asthma (US EPA, 2013). These effects are linked to more emergency room visits, hospitalizations, and absenteeism, and higher health care costs (Willey et al., 2004).

The map and charts below show the levels of ozone at individual monitoring stations, and the assigned management levels for each of B.C.’s air zones. Each point shown on the map represents an air quality monitoring station with colours that describe the management level after removing the effects of wildfires and transboundary flows. The colour of each region is the management level assigned for the entire air zone, with values based on the station with the highest level of ozone. The results shown here are based on the 2022–2024 reporting period. The four management levels and the recommended actions are: (1) green (actions for keeping clean areas clean); (2) yellow (actions for preventing air quality deterioration); (3) orange (actions for preventing Canadian Ambient Air Quality Standard exceedance); and (4) red (actions for achieving air zone Canadian Ambient Air Quality Standard). Each management level corresponds to actions that become more rigorous as the level of ozone approaches CAAQS. Suggested actions for each management level are outlined in the Guidance Document on Air Zone Management. More information on management levels can be found below.

While the Guidance Document outlines the types of actions that may be taken at each management level, a range of actions are implemented across British Columbia to improve air quality. These actions may include provincial programs, regulatory measures, and community-level initiatives that address local sources of air pollution and vary by region. Examples of actions include programs to reduce emissions (such as wood smoke reduction initiatives), controls on open burning, and local or regional efforts to manage air quality. Summaries of actions and activities undertaken in B.C. can be found in Air Zone Management Response reports, which describe provincial and local efforts to improve air quality in different regions.

The map shows air quality stations with sufficient data to report for the 2022-2024 reporting period. When you click on a station, a graph appears showing both the original data and data that has been adjusted for Transboundary Flow and Exceptional Events (TF/EE). TF/EE adjustments occur when air pollutants travel from other geographic regions to B.C. (TF) or when rare, natural, or human-induced events such as intrusion from upper atmospheric ozone, or wildfire impact air quality (EE). TF/EE adjustments remove the pollutants caused by these events because they are unpredictable and not part of typical/controllable emissions.

Tip: Click or tap on an air zone or monitoring station to see details on the status of ozone levels for the 2022-2024 reporting period.

Tip: See Table 6.1 in the Guidance Document on Air Zone Management for more information about the suggested actions for each color/management level in the map below.