What is the New Source Review (NSR) Air Permitting Program?

• Morgan Lachance

• Last Updated: December 16, 2025
• Types of NSR Permits
• Recent Updates to the NSR Program
• Final Thoughts

The New Source Review (NSR) program is an important component of the Clean Air Act (CAA) designed to protect air quality and public health by regulating air emissions from new and modified industrial facilities. Established as part of the 1977 Clean Air Act Amendments, the NSR program ensures that air quality does not degrade in areas where it is already clean and improves in areas where it is not.

The NSR program requires industrial facilities to obtain permits before construction begins. These permits require the installation of modern pollution control technologies to limit emissions. The primary goals of NSR are to:

• Prevent Significant Deterioration (PSD): Ensure that air quality in attainment areas (areas meeting National Ambient Air Quality Standards, or NAAQS) does not significantly degrade.
• Nonattainment NSR: Improve air quality in nonattainment areas (areas not meeting NAAQS) by requiring stricter emission controls.
• Minor NSR: Apply to smaller sources or modifications that do not qualify as major sources.

Types of NSR Permits

There are three main types of NSR permits, each with specific requirements:

1. Prevention of Significant Deterioration (PSD) Permits:

• Best Available Control Technology (BACT): Facilities must install the best available technology to minimize emissions.
• Air Quality Analysis: Assess existing air quality and predict future impacts.
• Additional Impacts Analysis: Evaluate the effects on soil, vegetation, and visibility.
• Public Involvement: Opportunities for public comment and hearings during the permitting process.

2. Nonattainment NSR Permits:

• Lowest Achievable Emission Rate (LAER): Facilities must implement the most stringent emission controls available.
• Emission Offsets: New emissions must be offset by reductions elsewhere to ensure no net increase in pollution.
• Public Involvement: Like PSD, with opportunities for public participation.

3. Minor NSR Permits:

• Apply to smaller sources or modifications that do not qualify as major sources.
• Requirements vary by state and may include state-specific emissions control measures.

Regulatory Changes and Environmental Justice

The NSR program has undergone various changes over the years, influenced by different administrations. For example, the Trump administration’s adjustments made the program more lenient, allowing more industrial projects to proceed without stringent emission controls. In contrast, the Biden administration has focused on strengthening the NSR program to better protect public health and the environment.

Additionally, the EPA has committed to advancing environmental justice in air permitting. This includes expanding best practices to consider the impacts of air pollution on marginalized communities to ensure that all populations benefit from clean air protections.

Recent Updates to the NSR Program

Recent updates to the NSR program include:

• May 3, 2024: Proposal to revise preconstruction permitting regulations for modifications at existing major stationary sources.
• April 30, 2024: Supplement to the Guidance on Significant Impact Levels for Ozone and Fine Particles in the PSD Program.
• April 30, 2024: Fact Sheet on Effective Permitting Tools for Fine Particulate Matter under the PSD Program.
• February 22, 2024: Revisions to Regulations Related to Project Emissions Accounting.

Final Thoughts

The NSR program helps improve air quality in the United States. It requires industrial facilities to attain permits and use modern pollution controls to protect public health and the environment. Regular updates and a focus on environmental justice guarantee the program adapts to current and future air quality challenges.

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