Air pollution readings across the Phoenix metro area soared to more than 14 times above normal levels Tuesday after a severe overnight dust storm blanketed the Valley and lingered well into the afternoon.
Michael Graves, an air quality meteorologist with the Arizona Department of Environmental Quality (ADEQ), told KTAR News 92.3 FM most valley monitors were reading above 200 micrograms per cubic meter, the particulate pollutant associated with dust.
A normal reading is below 50, said Graves. Several readings topped 300. One exceeded 500 and another climbed above 700. ASU rated it a Category 5 on its new PHX-DUST Scale, the highest level on the 1-to-5 post-event classification system for ranking dust storm severity…