Missouri Department of Environmental Quality – St. Louis Ozone Nonattainment Area
The Missouri portion of the St. Louis metropolitan area—including St. Louis City, St. Louis County, St. Charles County, Jefferson County, and Franklin County—is classified as a Serious nonattainment area under the 2015 8-hour ozone National Ambient Air Quality Standards (NAAQS).
Under the federal nonattainment New Source Review (NSR) program, new or modified major stationary sources of ozone precursors—namely nitrogen oxides (NOx) and volatile organic compounds (VOC)—must obtain Emission Reduction Credits (ERCs) to offset any proposed increase in emissions. The offset ratio for a Serious ozone nonattainment area is 1.2 to 1. For instance, a new source proposing 100 tons/year of NOx would need to secure 120 tons/year of NOx ERCs.
| Pollutant | New Major Source Emission Rates | Major Modification to existing Source |
|---|---|---|
| Nitrogen oxides (NOx) | ≥50 tons/year | ≥25 tons/year |
| Volatile Organic compounds (VOC) | ≥50 tons/year | ≥25 tons/year |
Facilities that were emitting NOx or VOC may be eligible to generate Emission Reduction Credits (ERCs) with a permanent reduction of those emissions generating from a shutdown or installation of control technology or process change.
If your company has a new project that exceeds thresholds or had a facility with permanent reduction of emissions at any level, please reach out to see how Emissions Experts can assist.