Wildfire smoke originating from a much greater distance than usual is believed to be behind the special air quality statement issued Thursday night for the Prince George and Vanderhoof areas.
"Because of changing wind directions and the number of fires, it can be difficult to pinpoint exactly where this smoke is coming from," B.C. Wildfire Service information officer Jessica Mack said in a statement.
"However, a phenomenon known as long range transport can carry smoke hundreds and even thousands of kilometres away from a fire.
"Over the last few days, smoke in the northern half of the province can be attributed to an upper low that has pulled smoke into B.C. from the fires currently burning in Manitoba and Ontario.
"Today, some of this smoke can even be accredited internationally, coming from countries such as Siberia and Eurasia!"
It was bad enough for Environment Canada and the B.C. Ministry of Environment to issue the statement over health concerns.
"Individuals may experience symptoms such as increased coughing, throat irritation, headaches or shortness of breath," officials said.
"Children, seniors, and those with cardiovascular or lung disease, such as asthma, are especially at risk.
"Stay inside if you have breathing difficulties. Find an indoor place that’s cool and ventilated. Using an air conditioner that cools and filters air may help. If you open the windows you may let in more polluted air. If your home isn’t air-conditioned, consider going to a public place (library, shopping mall, recreation centre) that is air-conditioned."
The Dog Creek Trail fire north of Fraser Lake remained listed as active but no longer of note on the B.C. Wildfire Service website.