Smoke from wildfires has blanketed part of suburban Portland, Oregon.

Drone footage September 13 shows how Northwest Portland has been shrouded in smoke, which has been described as "hazardous" by state environmental officials.

Massive clouds of smoke from the Pacific Northwest wildfires lingered over the region Sunday, posing serious health risks for millions of people and complicating firefighting efforts even as crews reported progress in slowing some of the blazes. The air quality across Oregon was listed as “hazardous” or “very unhealthy” by state environmental officials, and a dense smoke advisory from the National Weather Service remained in effect for much of the state until late Sunday or at least noon local time on Monday. Oregon officials said Sunday evening that crews are struggling to contain more than 30 fires still raging across the state — one of them stretching more than 55 miles wide, part of a burned area larger than Rhode Island.