Ozone season recap: In like a lamb, out like a lion

What’s up with the exceedances? 

The reasons for exceedances varied, and the exceedances were distributed throughout the season. Controlled burns in the Flint Hills heavily influenced the earliest exceedance on April 14. June 23 was nearly all locally generated ozone pollution that built up during one of those long days shortly after the solstice where lots of sunlight fueled the chemical reaction. Exceedances later in the season occurred as sunny, warm and dry conditions predominated, including Oct. 12, which saw temperatures in the 90s.

While ozone concentrations exceeded the federal limit on six days, said Karen Clawson, MARC Air Quality and Climate Programs manager, she said the 2024 season was better than the previous year. Nonetheless, despite the improvement, the region still appears to have violated the federal ozone standard again this year.

“We also track particulate matter (PM) in the region, though somewhat differently than ozone,” Clawson said. “There are two different standards for PM. We generally meet the daily standard, but there is also an annual standard that complicates our work. PM is difficult to forecast and it’s a year-round issue.”

In mid-May, Kansas City, Kansas, had the worst air quality in the United States due to wildfire smoke. But days like these, where air quality conditions are beyond human control, can receive a waiver from the federal government. 

“Such readings are considered ‘exceptional events’ and are omitted from the design value calculation,” Clawson said. A design value calculation is a statistical method used to determine the air quality status of a specific location by comparing pollution concentrations at that site to the National Ambient Air Quality Standards. 

Because the PM standard was updated and strengthened in early 2024, the U.S. Environmental Protection Agency requires states to submit initial area designations within one year of the new standard, Clawson said. Missouri and Kansas are working through this process now and will have public comment periods in January 2025.