(Portland, OR)  --  Portland's air quality continues to suffer dramatically as wildfires burn across the region.  The Environmental Protection Agency listed Portland's air quality index in the hazardous range at 516 as of early this morning.  KATU-2 reports the city's air quality was ranked as the worst in the world yesterday, followed by Vancouver B.C. and Seattle, Washington.  Health officials are urging residents to stay inside whenever possible.