Arizona Air Quality Information

Phoenix AQ History: Dust Storm Causes Hazardous Air Quality


Out of all the calendar days in 2018, August 2 sticks out like a sore thumb. First of all, this day was one of only three days in 2018 on which ozone, PM10 (dust), and PM2.5 (fine particulates) exceeded the federal health standard.

The Valley saw its highest PM10 levels of the year on August 2, 2018, because of a powerful dust storm from the south (see time lapse). PM10 levels topped out at an AQI of 399 (Hazardous category) in Apache Junction. Three monitors in Maricopa County saw PM10 reach the Unhealthy AQI category.

Phoenix also saw its highest ozone levels of the year, with maximum ozone levels reaching an Air Quality Index (AQI) of 161 (Unhealthy category). In fact, ozone exceeded the standard at 20 monitors in Maricopa County. To view the air quality summary for all monitors across the state from August 2, 2018, click HERE.

Fortunately, the Valley hasn't seen such an extraordinary air quality day this year yet. And it's possible that the Valley won't see one. Sure, we still have time to see high ozone levels. After all, ozone is currently forecast to exceed the health standard every day today (August 2) through at least Tuesday (August 6). However, the potential for seeing a dust storm like last August 2 appears to be small. The reason for this? Rain!

[View Current Air Quality Forecast]

In late July, the southern deserts received widespread rainfall from monsoonal thunderstorms (see picture). The rain helped to stabilize soils and thus, reduce the potential for dust. Though the deserts can still dry out under hot temperatures, and though dust storms are still possible this monsoon season, recent rain is expected to prevent a dust storm like we saw last August 2.

In all, this just goes to show that no monsoon season is the same.