Thousands battle US-Canada wildfires as smoke causes air quality alerts

Wildfires across the western United States and Canada put millions of people under air quality alerts on Sunday as thousands of firefighters battled the flames, including the largest wildfire in California this year.

The so-called Park Fire had scorched more than 550 square miles (1,430 square kilometres) of inland Northern California as of Sunday morning, darkening the sky with smoke and haze and contributing to poor air quality in a large swath of the Northwestern US and western Canada.

Although the sprawling blaze was only 12 per cent contained, cooler temperatures and increased humidity could help crews battle the fire, which has drawn comparisons to the 2018 Camp Fire that tore through the nearby community of Paradise, killing 85 people and torching 11,000 homes.

Paradise and several other Butte County communities were under an evacuation warning Sunday. However, Cal Fire operations section chief Jeremy Pierce had some good news for the area, saying around midday that the Park