Dust storm

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.
“This looks like a whiteout almost when I’m looking in the distance in Phoenix,” he said.
Thunderstorms in Pima County late Monday generated high winds that carried dust across the lower deserts and into the Valley.
With no rain behind it, the dust lingered far longer than usual, Graves said. Cloud cover helped trap the dust close to the surface.
ADEQ issued a high pollution advisory for the Valley, automatically triggering a no-burn day under Maricopa County rules. Officials urged people with asthma, COPD and heart or respiratory disease to limit outdoor activity.
An active monsoon pattern could push another round of dust into the Valley Tuesday night, with additional chances Wednesday and Thursday as thunderstorms develop across the region, Graves said.