An air quality advisory for Metro Vancouver and the Fraser Valley due to wildfire smoke blowing into the region has been lifted.
Lower Mainland residents are breathing easier because of more favourable wind conditions from a change in the weather pattern.
“We’ve seen wind coming from a cleaner direction,” said Julie Saxton, an air quality planner for Metro Vancouver.
“That wind has been quite strong in places. That has brought us some cleaner air and helped move the smoke out of our area.”
Some drizzle in a few areas has also helped, and more showers are in the forecast for the weekend.
The advisory was first issued last Sunday for Metro Vancouver and unprecedented levels of fine particulate three to four times the region’s objective were measured at several test stations over the initial 24 hours.
“This has been a very unusual and difficult week for everybody here,” Saxton said.
“The concentrations of fine particulate matter we saw, especially in the early part of the week on Sunday and Monday, were among the highest I’ve ever seen for this area.”
The Fraser Valley was added to the areas under advisory Monday and elevated levels of ground-level ozone were listed as an additional factor starting Wednesday.
Saxton said the arrival of cloud and cooler temperatures by Friday also helped stop the generation of ground-level ozone, which is caused when nitrogen oxides and volatile organic compounds (from vehicle emissions, solvents and vegetation) react in sunlight on hot days.
It’s impossible to say whether the smoke will be back in the days ahead, Saxton said, noting wildfire activity and wind direction are both unpredictable.
Fraser Health spokesperson Tasleem Juma said area hospitals saw higher than usual numbers of patients treated for respiratory difficulties.
Satellite view last weekend of the wildfire smoke concentrated over southwestern B.C. NASA image.