The New Source Performance Standards (NSPS) and National Emission Standards for Hazardous Air Pollutants (NESHAP) are distinct components of the Clean Air Act designed to manage air emissions from industrial sources.

National Emissions Standards for Hazardous Air Pollutants (NESHAP)

Under Section 112 of the Clean Air Act, the U.S. Environmental Protection Agency (EPA) establishes NESHAPs to limit the release of Hazardous Air Pollutants (HAPs) - such as asbestos, benzyl chloride, chlorine, and formaldehyde - into ambient air in order to protect public health and the environment | View NESHAPs >

In this program, the EPA identifies sources of HAPs and establishes nationwide, technology-based emission standards for these sources. The stringency that applies to the facility depends on whether a facility is classified as a “major source” or an “area source.” Major stationary sources require the most stringent technology-based pollution control called Maximum Achievable Control Technology (MACT). A major source is a stationary source with the potential to emit at least 10 tons per year (TPY) of a single HAP or 25 TPY of a combination of HAPs. For stationary sources with emissions below these thresholds, the EPA may impose Generally Available Control Technology (GACT), which is less stringent than MACT. 

Every eight years after a MACT standard is adopted, the EPA is required to conduct a Risk and Technology Review (RTR). During this process, the EPA evaluates whether advancements in control technology justify imposing stricter emission standards. At the same time, the EPA also performs a risk analysis to identify any risks to public health and the environment remaining after the imposition of MACT. If necessary, the EPA will revise the MACT to reflect new technology or to ensure the protection of public health with an ample margin of safety, whichever is more protective | View Risk and Technology Review >

NESHAPs in Arizona

The EPA may delegate the authority to implement and enforce NESHAPs to states or other local agencies. In Arizona, ADEQ enforces NESHAPs through delegation and its permitting program. NESHAPs delegated to local air quality agencies are codified in the Code of Federal Regulations (CFR), Title 40, Parts 61.04 and 63.99.

Examples of sources regulated under NESHAPs in Arizona are:

• The removal and disposal of regulated asbestos-containing material (RACM) 
• Dry cleaning facilities
• Glass manufacturing plants
• Primary copper smelting
• Wood furniture manufacturing

New Source Performance Standards (NSPS)

Under Section 111 of the Clean Air Act, the EPA establishes NSPS to regulate air emissions from new or modified stationary sources. These technology-based standards are codified in 40 CFR Part 60 and ensure that new or modified sources operate using the Best System of Emission Reduction (BSER) technology. NSPS apply not only to newly constructed sources but also to modifications of existing sources that result in an increase in emissions or a change in the types of emissions.

In this program, the EPA identifies source categories that contribute significantly to air pollution which may reasonably be anticipated to endanger public health or welfare and develops NSPS for them. Sources subject to the NSPS must monitor and test their emissions and comply with emission limitations.

As in the case of NESHAPs, the EPA is required to review the NSPS every eight years, and if necessary, revise the NSPS to reflect advancements in control technology | View Standards >

NSPS in Arizona

The EPA may delegate the authority to implement and enforce NSPS to states and other local agencies. A complete list of Arizona delegated sources subject to NSPS can be found in 40 CFR Section 60.4. Like the NESHAPs, the NSPS can also be enforced in Arizona through state and local air quality permit programs.

Examples of NSPS sources in Arizona are:

• Fossil-fuel-fired steam generators
• Portland cement plants
• Nitric acid plants
• Primary copper smelters
• Coal-fired power plants
• Landfills
• Stationary compression ignition internal combustion engines