Arizona Air Quality Information

First time PM10 (dust) exceeds health standard in 2019


On Tuesday, April 9, a strong Pacific storm system was fast approaching Arizona from the west. This system caused breezy west-southwest winds of 15-25 mph throughout the afternoon in Phoenix, with wind gusts up to 30 mph. Winds also picked up again later toward midnight. By the end of the day, PM10 (dust) levels still remained in the Good Air Quality Index (AQI) category across most monitoring sites in the Valley. However, one site--the West 43rd monitor--saw significantly high PM10 levels throughout the afternoon and evening--more than enough for PM10 to exceed the federal health standard. This was the first time PM10 had exceeded the standard since September 2, 2018 (that's 220 days!).

Then, in the early morning hours on Wednesday the 10th, widespread dust entered Arizona's central deserts from the west, causing all PM10 monitoring sites around the Valley to see elevated PM10 levels. A haze was even evident around the Valley during the time of the morning commute. Winds quickly picked up again and helped to clear out the Valley's air temporarily. But gusty winds out of the west throughout the rest of the morning and afternoon resulted in additional dust in the Valley. A PM10 High Pollution Advisory was issued in the morning for the day, since PM10 was expected to exceed the heath standard again.