Updated 1753 GMT (0153 HKT) August 21, 2018
With hundreds of wildfires burning across British Columbia and the western United States, smoke is now an everyday occurrence in the Pacific Northwest.
"Unhealthy air has become common across the area due to smoke from wildfires," the National Weather Service said Tuesday in its air-quality alert.
On Monday, air quality in Seattle reached one of the worst levels it has seen this year. And an "unhealthy" air-quality index was reported from British Columbia to Northern California.
When air is measured in the "unhealthy" category, everyone -- not just sensitive groups -- may begin to experience health effects, according to the Environmental Protection Agency.
British Columbia had more fires burning on Tuesday than at any point last year, and the wildfire season still has months to go. Last year was a record year for acres burned across the province, and so far this year is already its third-worst on record.
The good news is that air quality will begin to improve later this week as the wind shifts direction. The bad news is the smoke has to go somewhere.
Like we have seen over the past few weeks, the smoke will continue to meander with the overall weather pattern. On Monday, smoke was already reaching Denver. The National Weather Service in Fort Worth, Texas, was predicting smoke across its horizon by late Tuesday.
At multiple points this month, satellite images have shown smoke caught up in the jet stream, which acts like a conveyer belt in the upper atmosphere, sending the smoke as far as the East Coast and even over the Atlantic.
