Highlights
- The Fountain Hills AirNow monitoring station recorded ozone at 72.0 PPB at 10 p.m. on May 21.
- That reading crossed AirNow's Unhealthy for Sensitive Groups breakpoint for ozone, according to Maricopa County Air Quality Department data.
- Residents with heart or lung conditions, children, and older adults should check the AirNow Phoenix forecast for current guidance.
The EPA AirNow monitoring station in Fountain Hills recorded ozone at 72.0 parts per billion at 10 p.m. Thursday, May 21, crossing the threshold AirNow designates as Unhealthy for Sensitive Groups, according to data reported by the Maricopa County Air Quality Department.
The reading was logged at AQS site ID 040139704, the county's Fountain Hills station. The Unhealthy for Sensitive Groups classification applies when ozone levels reach a range that poses elevated risk for certain populations; the Maricopa County Air Quality Department is the reporting agency for this station.
Residents seeking current forecasts, active advisories, or health guidance should check the AirNow Phoenix-area page directly. The Maricopa County Air Quality Department also maintains an alert signup for High Pollution Advisories at its official air quality page.
The AirNow Phoenix-area forecast page will reflect any updated readings or advisories as conditions change overnight.
Sources
Every factual claim in this article traces to one of the sources below. See how we work for the editorial process.
- 040139704 retrieved 21/05/2026 23:31
- Maricopa County retrieved 21/05/2026 23:31
Authored by The Scottsdale Signal. Drafted by AI from primary-source material under our beat-specific editorial guides; reviewed by humans before publish under our five-gate process. Sources retrieved at 21/05/2026 23:31. Every claim traces to a source.
