Ground-level ozone in Washoe County recently exceeded national safety standards

Jun 21, 2024

June 21, 2024. Reno, Sparks, Nev. – Northern Nevada Public Health’s (NNPH) Air Quality Management Division (AQMD) is alerting residents that on the evening of June 14, 2024, through the early morning of June 15, 2024, air quality in the Reno-Sparks area reached an Unhealthy for Sensitive Groups (USG) stage for ground-level ozone, recording an exceedance of the National Ambient Air Quality Standards (NAAQS).

This exceedance took place between 8 p.m. on June 14 and 3 a.m. on June 15 and was detected at our Lemmon Valley monitoring station. There is no current threat of ozone exposure at this time. This rise in ground-level ozone was due to a rare occurrence where upper atmospheric ozone mixed down to cause unhealthy levels of ground-level ozone.

Breathing ozone can trigger a variety of health problems including chest pain, coughing, throat irritation, and congestion. It can worsen bronchitis, emphysema, and asthma. Ground-level ozone also can reduce lung function and inflame the linings of the lungs. Repeated exposure may permanently scar lung tissue.

Fortunately, you can see real-time air quality at and get real-time alerts on ozone levels  in Washoe County at EnviroFlash. These air-quality notifications alert residents of unhealthy air quality, even when AQMD staff may be unable to provide immediate alerts.

“While there is no current threat to air quality, this notification system helps alert all of us when there are issues that could impact overall health,” said Francisco Vega, Division Director of AQMD. “It’s not only helpful, but required by our regulations.”

Ground-level ozone is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight. The highest ozone levels occur in the summertime when temperatures are high and emissions from motor vehicles, stationary sources, and others mix to form ground-level ozone.

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For more information the NNPH’s Air Quality Management Division, visit


Please note the Washoe County Health District changed its name to Northern Nevada Public Health on Aug. 31, 2023. More information is here.

Northern Nevada Public Health (NNPH) is nationally accredited by the Public Health Accreditation Board and has jurisdiction over all public health matters in Reno, Sparks, and Washoe County through the policy-making District Board of Health. NNPH consists of five divisions: Administrative Health Services, Air Quality Management, Community and Clinical Health Services, Environmental Health Services and Epidemiology & Public Health Preparedness. More info can be found here.