Smoke from wildfires in Canada has spread more than 5,000 miles, reaching parts of Russia as well as other parts of Europe during the past week.

Smoke from several Canadian wildfires has drifted into the Bay Area, causing officials to warn of worsening air quality through Wednesday. The Bay Area Air Quality Management District has extended an air quality advisory first issued Monday,

Many fires burning across Canada, forcing evacuations and threatening air quality in the United States, cannot simply be put out, authorities and experts say.

As the climate changes, the far north is drying and warming, which means wildfires are getting bigger and more intense. The area burned in Canada is now the second largest on record for this time of year,

Fire experts call them “zombie fires.” That definition comes from a specialist in the measurement of Canada’s raging