Portland, Oregon is ranked number one in the entire world for worst air pollution as wildfires ravage Americaâs west coast. According to IQAir, an air purifier company tracking the world's live pollution levels, Portlandâs air quality index level is 206, which is described as âvery unhealthy.â Forecasts predict the cityâs air quality could only get worse in the coming days. The pollutant causing Portland to rank so high is called PM2.5 and itâs reportedly one of the most dangerous pollutants in the United States. IQAir advises those in the area to wear a mask outside, keep windows closed, avoid outdoor exercise, and to use an air purifier in order to protect themselves against air pollution. The Environmental Protection Agency live map of air quality over the U.S. shows a dire situation for the entire west coast, from Seattle down to Los Angeles. A historically unprecedented rash of wildfires have burned millions of acres in the west, leaving at least 17 dead as of Saturday morning.