This time of year, ozone is the air pollutant at the forefront of our minds. You may be thinking: isn't ozone good? Ozone is good when it's in the stratosphere. But at the ground, it can have negative impacts on human health. It forms out of the complex interactions between local pollution emissions and sunlight.

Yesterday (Thursday), ozone exceeded the federal health standard at several monitors in the Phoenix Valley.

Looking ahead, ozone is forecast in the Moderate AQI category through the weekend and into next week. It will undergo its usual, daily cycle of increasing into the afternoon. But, stronger daytime winds are expected to help limit ozone levels, keeping them below the health standard threshold.

PM10 (dust) and PM2.5 (smoke) should continue to be highest in industrial areas south/southwest of the Phoenix metro area. The hourly forecast graphs reflect activity in these areas. But, winds should also help to disperse local PM10/PM2.5 levels.

Of course, we can't rule out pockets of dust from dust-prone areas during breezier periods. Such times currently look to be the next few afternoons and/or evenings.

Check back again on Monday for the next Phoenix Air Quality Forecast.

- M. Graves
ADEQ Meteorologist