The Oklahoma Department of Environmental Quality (DEQ) released their combined 5-Year Network Assessment and Annual Monitoring Network Plan on May 16, 2025. It is available for public review and comment through June 16, 2025. It contains ambient monitoring changes for the upcoming year and an evaluation of network effectiveness. The two reports must be submitted to the U.S. Environmental Protection Agency (EPA) by July 1, 2025. EPA requires each state to complete ambient monitoring network assessments every five years to determine if the existing network meets the monitoring objectives presented in Appendix D of
40 CFR Part 58. The assessment also determines if new sites are needed, whether existing sites are no longer needed, and if new technology will better support the monitoring network. Factors to consider may include the ability to monitor at-risk populations and the effect data will have to assist in health effect studies. These assessments have been due every five years since July 1, 2010.
In addition to the 5-year assessment, the state is required to submit a revised annual network plan. The annual monitoring plan includes documentation on establishing and maintaining air quality surveillance systems. Each monitor is reviewed to verify that it meets the requirements of Appendices A, B, C, D, and E of 40 CFR Part 58. If the plan includes any changes to the network such as adding new or discontinuing sites, this must undergo approval from EPA. Several factors may necessitate the need for a revised network in a core-based statistical area (CBSA) such as having a population greater than 1,000,000 and having a population greater than 2,500,000.
5-Year Assessment Summary
In its current state, Oklahoma’s network is operating efficiently, but some updates over the next five years are still planned. DEQ has begun to investigate small sensors. They could potentially test siting areas for pollutant levels before establishing monitoring sites. This will be most prevalent in monitoring fire emissions to better provide data to the air quality health advisory program. These low-cost sensors are currently being assessed and will be in an ongoing study. Currently, DEQ plans to expand these low-cost monitors along the Red River to provide additional information regarding ozone transport across state lines.
Based on updated population data, the Tulsa CBSA has exceeded a population of 1,000,000. This has initiated the installation of a photochemical assessment monitoring station (PAMS) and a near-road monitoring site. This will add the following monitoring capabilities:
- PAMS
- Hourly averaged speciated volatile organic compounds (VOC)
- Three 8-hour averaged carbonyl samples per day on a 1-in-3 day schedule, or hourly averaged formaldehyde
- Hourly averaged true nitrogen dioxide (NO2)
- Hourly averaged atmospheric pressure
- Hourly precipitation
- Hourly averaged mixing-height
- Hourly averaged solar radiation, and
- Hourly averaged ultraviolet radiation
- Near-Road
- Hourly averaged NO2
- Hourly averaged carbon monoxide (CO)
- Hourly averaged black carbon
- Hourly averaged particulate matter (PM2.5 and PM10)
Summary of EPA’s Comments on Oklahoma DEQ’s 2024 Annual Monitoring Plan
After reviewing DEQ’s 2024 Annual Monitoring Plan, EPA’s confirmed the monitoring network is following the minimum federal standards listed in 40 CFR Part 58. Oklahoma is meeting the minimum monitoring requirements for the following compounds:
- Ozone
- CO
- NO2
- Sulfur dioxide (SO2)
- Lead
- Particulate matter
Additionally, DEQ has proposed monitoring network changes for the following compounds:
- Relocation of the existing ozone Glenpool monitoring site in Tulsa
- Near-road monitoring for CO to be collocated with the proposed near-road NO2 monitor station in Tulsa
- PAMS monitoring to be located in Tulsa with an anticipated start time around Summer 2025
- Relocation of the existing lead monitor site in Savanna
- Use of T640X monitors for PM
- Near-road monitoring of PM2.5 to be collocated with the proposed near-road NO2 monitor station in Tulsa
