An air quality advisory issued earlier this week remains in effect for Metro Vancouver and the Fraser Valley due to high concentrations of fine particulate matter and ground-level ozone.
In a statement, the weather agency said wildfire smoke from fires in Washington and Oregon continue to impact the region’s fine particulate matter concentrations and that these conditions are expected to persist until at least tomorrow.
Fine particulate matter, also known as PM2.5, refers to airborne solid or liquid droplets with a diameter of 2.5 micrometres (µm) or less. PM2.5 can easily penetrate indoors because of its small size.
As well, “today’s forecasted hot temperatures combined with wildfire smoke will cause elevated ground-level ozone concentrations,” the agency said.
Ground-level ozone is not emitted directly into the air, but rather it is formed when nitrogen oxides (pollutants emitted when fuels are burned) and volatile organic compounds (emitted from solvents) react in the air in the presence of sunlight.
The air quality advisory is in effect for the following areas:
- Metro Vancouver – NE
- Metro Vancouver – NW
- Metro Vancouver – SE
- Metro Vancouver – SW
Environment Canada also noted that smoke concentrations may vary widely across the region “as winds and temperatures change, and as wildfire behaviour changes.”
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In the meantime, anyone with chronic underlying medical conditions or acute infections such as COVID-19 is advised to postpone or reduce outdoor physical activity until the advisory is lifted, “especially if breathing feels uncomfortable.”