By Timothy P. Fagan, BLR Air Expert
National Ambient Air Quality Standards (NAAQS)
The CAA required EPA to develop NAAQS for six pollutants commonly found throughout the United States. These pollutants, referred to as “criteria pollutants,” are:
- Sulfur dioxide;
- Particulate matter (PM-10 and PM-2.5);
- Carbon monoxide;
- Nitrogen dioxide; and
For each criteria pollutant EPA established a primary and a secondary NAAQS. The primary standard establishes a level of the pollutant in the ambient air that will allow for the protection of human health. The secondary standard is established to prevent environmental and property damage. Every 5 years the standards are reviewed.
Each state has a network of monitoring stations to determine ambient concentrations of criteria pollutants. EPA uses the monitoring data to determine each area’s attainment status on a pollutant-by-pollutant basis. Areas with an ambient concentration below the NAAQS are designated attainment, while areas exceeding the NAAQS are designated nonattainment. Ozone, CO, and PM-10 have multiple classifications of nonattainment that indicate the severity of pollution in the area.
Impact on Permitting
The goal in nonattainment areas is to improve the air quality and move towards attainment, whereas the objective in attainment areas is to maintain its attainment status. As a result, the permitting requirements in nonattainment areas are generally more stringent than those in attainment areas.
Construction permits. Construction permits for new major sources and major modifications are divided Nonattainment New Source Review (NNSR) requirements nonattainment areas, and Prevention of Significant Deterioration (PSD) requirements for attainment areas. Because the attainment status is determined by pollutant, it is possible for one source to be subject to NNSR for one pollutant and PSD for another. Some of the difference between NNSR and PSD include:
- Emissions thresholds for applicability. In general, NNSR thresholds are lower than those of PSD, causing a greater spectrum of sources to require permits and be subjected to the more stringent emissions controls of NNSR. For ozone, CO, and PM-10, the thresholds are even lower based the severity nonattainment classification.
- Emissions controls. PSD requires best available control technology (BACT), which is the maximum degree of emissions reduction available for each pollutant subject to regulation, taking into account energy, environmental, and economic impacts and costs. NNSR requires lowest achievable emissions rate (LAER), which is the most stringent limit in any state implementation plan or achieved in practice by similar sources.
- Addressing emissions increases. NNSR requires facilities to obtain offsets, either by decreasing emissions within the facility or by purchasing emissions credits. Offsets must be greater than the proposed increases to ensure the project has a net environmental benefit and the area where it is located can continue to move toward attainment. Under PSD, sources must use computer modeling to demonstrate that proposed emissions will comply with the NAAQS and the PSD increment, the maximum allowable increase in ambient concentration of criteria pollutants for the given area. This controls the rate at which pollution in the area is allowed to approach the NAAQS.
Operating permits. Major sources are also required to obtain Title V operating permits. As with construction permits, emissions levels for Title V applicability are impacted by a nonattainment designation. The emission thresholds for applicability are lower for ozone, CO, and PM-10 based the severity of the nonattainment classification.
Any time a new source or a modification to an existing source of air pollution is being considered, the first steps include compiling an emissions inventory and reviewing 40 CFR 81, Subpart C to determine the attainment status of the area where the proposed source/modification will occur. This information will help you determine where to begin your permitting process.
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Timothy P. Fagan is a Legal Editor for BLR’s environmental publications, focusing primarily on air quality related topics. Mr. Fagan has covered environmental developments with BLR since 2000. Before joining BLR, he spent 5 years in environmental consulting and was responsible for air quality permitting and compliance for a broad range of industries in both the private and public sector. He received a Bachelor of Science degree in chemical engineering from Villanova University and a Master’s degree in environmental engineering from the Pennsylvania State University.