‘Unprecedented’ wildfire smoke in Lower Mainland, report says
This summer’s episodes of wildfire smoke drifting from the B.C. Interior into the Lower Mainland were “unprecedented” in their duration and the geographic area they affected, according to a Metro Vancouver staff report.
The report, which senior project engineer Francis Ries prepared for the climate action committee, noted that the regional district issued five air-quality advisories during the summer of 2017, resulting in advisories being in effect for a record 19 days.
Metro Vancouver operates the air-quality advisory service for the entire lower Fraser Valley airshed, including the Metro Vancouver region and the Fraser Valley Regional District. The B.C. Ministry of Environment issues air-quality advisories for the rest of the province.
An advisory for ground-level ozone — a main constituent of smog that is formed when nitrogen oxides and volatile organic compounds react in sunlight — was in place July 6 and 7. An advisory for fine particulate matter from forest fires was in place July 18 and 19. Three advisories for both groundlevel ozone and fine particulate matter were in effect Aug. 1-12, Aug. 29-30 and Sept. 4-9.
Hotter than usual weather combined with wildfire smoke from the Interior resulted in the high number of days with advisories.
The report compared this year’s smoky conditions to what the region experienced during the 2015 wildfire season.
The levels of fine particulate matter in the air were “somewhat” lower than those measured at the height of the July 2015 wildfire advisory, “but both the duration and geographic scope of wildfire smoke impacts in 2017 significantly exceeded those experienced in 2015.”
Similar to 2015, ground-level ozone advisories had to be added to wildfire-smoke advisories. However, despite reductions in temperature and solar radiation, ground-level ozone production actually increased during two of the smoke-related advisory events. Both hot temperatures and solar radiation, which contribute to ground-level ozone production, are often reduced by the presence of smoke in the air.
Hotter than usual weather and wildfire smoke bumped up the number of air-quality advisory days.