Smoky haze from wildfires in Canada engulfed New York City on Wednesday
Smoke from hundreds of wildfires in Canada reached Europe on Friday after blanketing provinces and large parts of the United States in thick smoke this week.
And while the noxious smoke was finally easing over the northeast on Friday, the fires still posed a major threat.
More than 420 fires are raging across Canada from British Columbia in the west to Nova Scotia in the east. At least half of these fires are burning out of control, and tens of thousands of people have been evacuated from their homes.
While air quality improved in large cities like New York, Washington DC and Philadelphia on Friday, pollution increased across central and southern states including the cities of Chicago, Cincinnati, Pittsburgh and Cleveland.
Global temperature rise, caused by emissions from burning fossil fuels, is leading to more large, erratic wildfires around the world. And it’s a vicious circle: the emissions pumped into the atmosphere by fires add to global heating, further drying out the land and vegetation, making it more susceptible to catching fire.