British Columbia operates a network of air monitoring stations that measure ground-level ozone and other air pollutants. This indicator reports on the concentration of ground-level ozone from 2020-2022 and compares it to the Canadian Ambient Air Quality Standard established by the Canadian Council of Ministers of the Environment.

• Ground-level ozone is an air pollutant. While ozone in the Earth’s atmosphere occurs naturally, additional ozone at the ground level is a pollutant. It forms through chemical reactions involving nitrogen oxides and volatile organic compounds in the presence of 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 below summarises the assigned management levels for ground-level ozone in B.C.'s air zones, as well as the levels of the pollutant at individual monitoring stations. The color of each region refers to the management level. The four management levels 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 is associated with a suite of actions that become more rigorous as ozone levels approach the standard. More information on Management Levels can be found below.

The map shows air quality stations with sufficient data to report for the 2020-2022 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 region to B.C. (TF) or when rare, natural, or human-induced events such as wildfire or volcanic eruptions 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 2020-2022 reporting period.

Tip: See Table 6.1 in the Guidance Document on Air Zone Management (CCME, 2019) for more information about the suggested actions for each color/management level in the map below.