The ozone season lasts from March 1 to October 31 and captures the warmest parts of the year when ozone production is more likely. Throughout the season, the MARC Air Quality Program tracks ozone readings and works with a team of meteorologists to produce the SkyCast—the daily ozone forecast. This forecast is communicated to the public through social media, weather reports, weather apps, EPA’s EnviroFlash alert system, and many other sources. When higher levels of ozone are forecasted, MARC issues an ozone alert.
This year MARC issued 14 ozone alerts, but the region saw 16 days where monitor readings exceeded the ozone standard of 70 parts per billion. These “exceedances” are measured by taking the fourth-highest eight-hour daily monitor reading.
June saw the highest number of exceedances of any month on record. One exceedance, on June 6th, reached red alert levels—the first red day since 2018. This rash of exceedances in June can be partly blamed on the wildfire smoke coming down out of eastern Canada, but also on the stagnant weather pattern that persisted for most of June.
At season end, all six monitors in the region have violated the 70 ppb standard for the year. On June 14, the Rocky Creek monitor in the Northland hit a reading that caused our “design value” for 2021-2023 to tentatively violate the National Ambient Air Quality Standards (NAAQS). The design value is the statistic that EPA uses to assess whether a given geography is in attainment with the national standard. The region’s design value now sits at 71 ppb, just above the standard.
The states of Kansas and Missouri will quality-check the data and go through a process of flagging days with exceedances that appear to have been impacted by external events. At this point, the implications of the Kansas City region tentatively exceeding the national standard for ozone are uncertain.
See the full 2023 Ozone Season Summary here.