Prevention of Significant Deterioration (PSD)

The Prevention of Significant Deterioration, or PSD, permit program was developed by the United States Congress to prevent significant environmental impacts on “attainment areas” from large industrial sources of air pollution. Attainment areas are regions of the United States where air quality meets the protective health standards established by the federal Clean Air Act. Pima County is currently in attainment of all the federal air quality health standards.

The PSD portion of the New Source Review (NSR) program is found in the Code of Federal Regulations at 40 CFR 52.21. The regulations apply to new or modified air pollution sources that are classified as “major” relative to air pollution emissions potential, and that are proposing construction projects that may “significantly” increase their air pollutant emissions. Under the PSD program, the new construction or modification must use air pollution control equipment and procedures determined by the Department of Environmental Quality to be the most effective for the project (Best Available Control Technology, or BACT). The applicant must also provide a detailed evaluation of the proposed project’s air quality impact on the local and regional environment. This evaluation must address air quality, visibility, soils, vegetation, and any specific air quality issues that may apply in national parks or wilderness areas.

Before the PSD program was developed, construction projects in large industrial facilities were being permitted with the primary goal of not worsening air pollution in problematic areas, and improving it if possible. Congress realized that this needed to be extended to ensure that those areas with clean, healthy air would stay that way, and that industrial activity would not significantly impact protected (e.g., wilderness) areas. Saguaro National Park has locations in the eastern and western regions of the Tucson area.

There are twenty-eight (28) specific industries or industrial processes that must meet the requirements of the PSD program if they emit, or have the potential to emit, at least 100 tons per year of any pollutant regulated by the federal Clean Air Act. These industries and processes are listed below. For all other industries, the PSD program applies if they emit or have the potential to emit at least 250 tons per year of any of any regulated pollutant. Regulated pollutants that most commonly lead to source-wide PSD applicability include particulate matter, carbon monoxide, sulfur dioxide, volatile organic compounds, and nitrogen oxides.

The 28 Industries or Industrial Processes Subject to PSD Requirements (if they have a potential to emit 100 tons per year or more of any pollutant regulated by the federal Clean Air Act) are:

• Coal cleaning plants with thermal dryers;
• Kraft pulp mills;
• Portland cement plants;
• Primary zinc smelters;
• Iron and steel mills;
• Primary aluminum ore reduction plants;
• Primary copper smelters;
• Municipal incinerators capable of charging more than 250 tons of refuse per day;
• Hydrofluoric, sulfuric, or nitric acid plants;
• Petroleum refineries;
• Lime plants;
• Phosphate rock processing plants;
• Coke oven batteries;
• Sulfur recovery plants;
• Carbon black plants using the furnace process;
• Primary lead smelters;
• Fuel conversion plants;
• Sintering plants;
• Secondary metal production plants;
• Chemical process plants, which shall not include ethanol production facilities that produce ethanol by natural fermentation included in NorthAmerican Industry Classification System codes 325193 or 312140;
• Fossil-fuel boilers, combinations thereof, totaling more than 250 million BTUs per hour heat input;
• Petroleum storage and transfer units with a total storage capacity more than 300,000 barrels;
• Taconite preprocessing plants;
• Glass fiber processing plants;
• Charcoal production plants;
• Fossil-fuel-fired steam electric plants and combined cycle gas turbines of more than 250 million BTUs per hour heat input

For industrial facilities subject to the PSD program, any projects involving construction or modification of pollutant-emitting processes will require a PSD permit if the potential emissions of a regulated pollutant are greater than the regulatory threshold. In addition to the regulated pollutants mentioned above, the following pollutants frequently lead to the need for a PSD permit: fluorides, sulfuric acid mist, hydrogen sulfide, and total reduced sulfur.

The Pima County Department of Environmental Quality (PDEQ) is designated as the air pollution control agency in Pima County, Arizona, and, acting through its Control Officer, PDEQ is authorized to issue preconstruction air quality permits to stationary sources under its jurisdiction that are, or would be, located in Pima County. Under the Code of Federal Regulations [40 CFR 52.21 (u)], EPA may delegate its responsibility to conduct PSD source review to state and local air pollution control agencies for sources within their jurisdiction. PDEQ and EPA agree that requirements in PSD permits issued by the Pima County Air Quality Control District pursuant to the following delegation of authority are federally enforceable. Pima PSD Delegation Agreement