VANCOUVER — A new weather system brought cleaner air and the promise of further improvements to parts of British Columbia on Saturday but conditions across the mountains were expected to worsen before getting better.
Smoke from wildfires burning in California, Oregon and Washington state has blanketed B.C., prompting respiratory health warnings that extended into southern Alberta and as far east as Saskatchewan Saturday.
An air quality advisory for Metro Vancouver and the Fraser Valley was lifted on Saturday after 11 days as cleaner marine air flowed into the area, although the regional government warned of pockets of smoke that could vary with winds and temperature changes.
Environment Canada said smoke began clearing across the western half of Vancouver Island early Saturday, and there should be widespread improvements further east by Sunday.
In the central portions of the province, the agency said smoke will be visible at higher elevations with potential for light to moderate effects.
Further east, the weather agency forecast more smoke in southern Alberta on Saturday, and issued special air quality statements for Jasper and Banff national parks, as well as Calgary and into south-central Saskatchewan.
It said smoky conditions across those areas was expected to worsen throughout the day, causing the air quality to deteriorate in many locations. As a weather system moved through the area Saturday night, conditions were expected to improve by Sunday.
It said air quality could become very poor in some parts of southwestern Saskatchewan.
Environment Canada meteorologist Jesse Wagar said the smoke in the upper atmosphere would continue to push towards eastern Saskatchewan and Manitoba.
Rain was expected in southern Alberta — in some cases large amounts in the area of Medicine Hat, close to the Saskatchewan boundary — which Wagar said would help clear the air in the longer term.
But initially, she said rain could further worsen the air quality, “because it brings down the smoke that’s aloft to the surface.”
“The spike in air quality is usually short-lived in those scenarios,” she continued.
“If you can get enough rain, it will clear the smoke.”
Environment Canada said people with chronic underlying medical conditions or acute infections such as COVID-19 should postpone or reduce outdoor physical activity until the advisories are lifted.
This report by The Canadian Press was first published Sept. 19, 2020.
The Canadian Press