VANCOUVER -- An air quality advisory that had been in place for more than 10 days in Metro Vancouver and the Fraser Valley has been cancelled, Metro Vancouver said Saturday.

"Air quality has improved due to cleaner marine air flowing into the region," the regional federation said in a statement.

That said, Metro Vancouver warns that pockets of local smoke may still be visible around the region.

Earlier in the day Environment Canada said air quality in southern and central British Columbia is expected to improve through the weekend as a new weather system moves in.

Smoke from wildfires burning in California, Oregon and Washington has blanketed the province, prompting respiratory health warnings.

Environment Canada says smoke is beginning to clear across the western half of Vancouver Island, and there should be widespread improvements farther east by Sunday.

In the central portions of the province, it says smoke will be visible at higher elevations with potential for light to moderate effects.

The air quality advisory in Metro Vancouver and the Fraser Valley was first put in place on Sept. 8 as smoke from U.S. wildfires increased the concentration of fine particulate matter in B.C. skies.

The smoke was so bad that Canada Post cancelled mail delivery in some parts of the province to protect the health of mail carriers. 

Teachers also called for children to have days off from school because of the smoke, but most districts opted to continue school and cancel activities that would have involved strenuous outdoor activity. 

At one point, Vancouver's air quality ranked among the worst in the world, trailing only U.S. cities closer to where the fires were burning. 

With files from The Canadian Press