Status of Ground-Level Ozone in B.C. (2019-2021)

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 2019-2021 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 asthma1. These effects are linked to more emergency room visits, hospitalizations, and absenteeism, and higher health care costs2.

The map below summarises the assigned management levels for ozone in B.C.'s air zones, as well as the levels of the pollutant at individual monitoring stations. It features stations with sufficient data to report for the 2019-2021 reporting period.

Tip: Click or tap on an air zone or monitoring station to see details on the status of ozone levels for the 2019-2021 reporting period.

Image of interactive map of air quality monitoring stations and air zones that meet or exceed Canadian Ambient Air Quality Standards for ground-level ozone. Your screen is too small to display the interactive map. Click to see the interactive visualization in full-screen.
  • Ozone levels met the Canadian Ambient Air Quality Standard at 45 of the 45 B.C. ozone monitoring stations. Ozone levels (see box below) from the 45 stations ranged from 38 to 58 parts per billion (ppb). Ozone levels were ≤ 50 ppb at 29 reporting stations (63%). No station reported ozone levels > 62 ppb.
  • Ozone levels met the Canadian Ambient Air Quality Standard in six of B.C.’s seven air zones. The ozone level for an air zone is the highest ozone level reported from monitoring stations within the air zone. Currently, there are no air monitoring stations in the Northwest Air Zone.
  • Ozone levels are used to set management levels for each air zone. Four management levels (green, yellow, orange, and red) are each associated with a suite of actions that become more rigorous as ozone levels approach the Canadian Ambient Air Quality Standard.

More about the Canadian Ambient Air Quality Standard for Ozone:

Canada-wide Air Quality Management System

The Air Quality Management System is Canada's approach for protecting air quality. Under the Air Quality Management System, provinces and territories monitor, report and manage local air quality within air zones, with the goal of continuously improving air quality and keeping pollutants below the Canadian Ambient Air Quality Standards.

  • There are seven air zones in British Columbia: Coastal, Georgia Strait, Lower Fraser Valley, Southern Interior, Central Interior, Northeast and Northwest.
  • The Air Zone Management Framework defines management levels based on the highest ozone level reported from monitoring stations within the air zone. 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). Actions for each management level are detailed in the Guidance Document on Air Zone Management (2019) (PDF). Air zone management levels are preferentially based on stations with 3 complete years of data.
  • The Coastal and Central Interior air zones were assigned to a green management level. The Southern Interior, Georgia Strait, and Northeast air zones were assigned to a yellow management level, and the Lower Fraser Valley was assigned to an orange management level. Currently, there are no air monitoring stations in the Northwest air zone.
Map of B.C. air zones and their associated air quality management levels for ground-level ozone.
Chart of B.C. air zones and their associated air quality management levels for ground-level ozone.

More about the Air Quality Management System management levels:

  • There are cases when an air zone does not achieve a given Canadian Ambient Air Quality Standard because of sources over which jurisdictions have little or no control over, such as those from transboundary flows and exceptional events, like wildfires.
  • Before assigning management levels, jurisdictions have the option to adjust their air zone metric values by removing external influences. These arrangements aim to ensure that jurisdictions are responsible for managing only the emissions they can control.
  • Wildfire influences were determined for 8 monitoring sites in B.C. on a total of 1 day for the 2019-2021 reporting period. The daily concentrations for these days were removed from the calculations of management levels, but this resulted in no changes in management levels for ground-level ozone.

Methods

The methods used to develop this indicator—including procedures, data requirements, and calculation of the ozone metric—are detailed in the Guidance Document on Achievement Determination: Canadian Ambient Air Quality Standards for Fine Particulate Matter and Ozone (2012) published by the Canadian Council of Ministers of the Environment.

R package and code: We have developed an R package to facilitate the calculation of air quality metrics according to the Canadian Ambient Air Quality Standards. Download the 'rcaaqs' package from GitHub. The source code for repeating the analysis presented on this page is also available on GitHub.

References and Other Useful Links

Data

*By accessing these datasets, you agree to the licence associated with each file, as indicated in parentheses below.

Download a printable version of this indicator (PDF)

Updated August 2024

Suggested Citation: Environmental Reporting BC. 2024. Status of Ground-Level Ozone in B.C. (2019-2021). State of Environment Reporting, Ministry of Environment and Climate Change Strategy, British Columbia, Canada.