November 24, 2025

Downstream Petroleum Sector Air Permit Types & Requirements

Even as federal priorities change for regulation of air emissions, one constant for the downstream petroleum sector is that state air agencies set the day-to-day pace of air quality regulatory compliance. Refineries and associated facilities are permitted and overseen through state implementation plans that administer federal Clean Air Act programs. For operators working across multiple states, staying on schedule means understanding the systems that states use to administer the various types of required air permits.

In this article, we provide a general description of state air permitting systems for the downstream petroleum sector, limited to air pollutants and hazardous air pollutants.

Downstream Petroleum Sector

Facility types included in the downstream petroleum sector include:

• Petroleum refineries
• Storage and terminals including crude oil and refined products (gasoline, diesel, jet fuel, lubricants, etc.)
• Product transfer, transportation, and loading
• Marketing and end-use fuel facilities (e.g., fuel dispensing to end users)

Air Pollutants of Concern

Air pollutants included in downstream petroleum sector include:

• Criteria air pollutants including nitrogen oxides (NOx), carbon monoxide (CO), volatile organic compounds (VOC), sulfur dioxide (SO2), particulate matter (PM2.5 and PM10).
• Hazardous air pollutants (HAPs) such as benzene, toluene, ethylbenzene, xylenes, and n-hexane, cumene, 1,3-butadiene, acetaldehyde, formaldehyde, methanol, phenol, and polycyclic aromatic hydrocarbons (PAHs), etc.  
• Greenhouse gases (GHG) including CO2, methane (CH4), nitrous oxide (N2)

Air Permit Coverage

In the downstream petroleum industry, air permitting frameworks are primarily concerned with stationary emission sources from fixed equipment and components that release regulated air pollutants. These sources are distinct from mobile sources such as on-road vehicles and nonroad engines, which typically fall outside the scope of stationary source air permits.

Key stationary sources at refineries and affiliated facilities include:

• Process equipment: sulfur recovery units, tail gas treatment, fired heaters, catalytic crackers, catalytic reformers, coking units, hydrotreaters, etc.
• Storage infrastructure: product atmospheric and pressurized storage tanks
• Transfer operations: loading racks for tank trucks, railcars, and marine vessels
• Combustion engines: backup generators, compressors
• Fugitive emissions: valves, pumps, flanges, connectors, and other leak-prone components
• Ancillary systems: wastewater treatment (benzene waste operations) units, cooling towers, flares
• Startup, shutdown, maintenance and malfunction (SSM) events

Air permits are typically not required for marketing and end-use fuel facilities.

Purpose of Air Permits in the Downstream Sector

State air permits serve as a key tool for meeting and enforcing federal air quality standards, particularly the National Ambient Air Quality Standards (NAAQS) for six criteria pollutants.

State permits also enforce federal programs like National Emission Standards for Hazardous Air Pollutants (NESHAP) regulations, which regulate hazardous air pollutants (HAPs). Most refineries are classified as major sources due to higher HAP emissions, while related storage and loading terminals are usually area (minor) sources, subject to less stringent requirements.

They also enforce New Source Performance Standards (NSPS) that apply based on facility type, process, emission source type, pollutant type, fuel used, and date of construction or modification, and include requirements for emission limits, monitoring, performance testing, and reporting.

Permitting requirements differ based on whether a facility is in an attainment or nonattainment area. Currently, over 50 nonattainment areas exist nationwide for ozone and particulate matter.

Air Permit Types

The types of state air permits and approvals for the downstream petroleum industry include the following listed below.

Major and minor permitting actions:

• Individual NSR and Operating Permits. These permits are used for major source permits for refineries and larger storage and transfer facilities. States also issue individual permits for minor sources at smaller standalone storage and transfer facilities. These apply to new facilities and modifications to existing facilities.

Minor permitting actions:

• Permit by Rule (PBR). These NSR permitting methods are established in state regulations that specify eligibility and compliance requirements.
• General Permits (GP). These NSR authorizations are approved by state regulations and issued through regulatory approval. Unlike PBRs, the regulations are less prescriptive, and the detailed requirements are contained in the permit document.

For projects at existing facilities, PBR and GPs can authorize smaller emission units and minor projects that meet certain eligibility criteria and do not trigger major NSR (i.e., are not major modifications under PSD or Nonattainment NSR).

New Source Review Permitting

New Source Review (NSR) is the comprehensive federal preconstruction permitting framework that includes the Prevention of Significant Deterioration (PSD), Nonattainment NSR (NNSR), and Minor NSR programs. Also states have their own NSR programs that cover criteria air pollutants, HAPs and GHGs. NSR permitting requires proposed new or modified emission units to obtain authorization and demonstrate compliance with applicable control technologies, monitoring protocols, and ambient air quality standards prior to construction.

The PSD program applies in attainment and unclassifiable areas to prevent significant deterioration of air quality while supporting economic development. PSD requires Best Available Control Technology (BACT) for each regulated pollutant emitted in significant amounts from new or modified major sources. BACT is a case-by-case emissions limit that reflects the maximum degree of reduction achievable for each pollutant, considering energy, environmental, and economic impacts. PSD permits apply to criteria air pollutants and GHGs.

The Nonattainment New Source Review (NNSR) program applies in nonattainment areas and promotes progress toward achieving the National Ambient Air Quality Standards (NAAQS). NNSR requires the application of Lowest Achievable Emission Rate (LAER) for each nonattainment pollutant emitted in significant amounts. LAER is a case-by-case emission limit reflecting the most stringent level of control achieved in practice or required by any state for similar sources, without consideration of cost. Unlike BACT under PSD, LAER does not allow for balancing of economic, energy, or environmental impacts in selecting emission controls. Under NNSR, new major sources or major modifications in a nonattainment area must offset emissions by obtaining reductions from existing sources. These offsets must provide a net air quality benefit, typically at a ratio greater than 1:1 (e.g., 1.1:1 or higher), depending on the pollutant and nonattainment severity.

The Minor Source NSR program governs preconstruction review for sources below major thresholds and is implemented through state-specific rules under the approved state implementation plan. Unlike the federally prescriptive PSD and NNSR programs, minor source NSR requirements vary by state, including applicability thresholds, control determinations, and authorization options such as individual permits, standard permits, and permits by rule (PBR).

Federal Operating Permits

A Title V permit functions as a comprehensive, facility-wide document that consolidates all applicable federal, state, and sometimes local air quality requirements for a site. This includes criteria air pollutants, HAPs and GHGs.

For both PSD- and NNSR-permitted refineries, the Title V operating permit serves as a comprehensive, federally enforceable document that incorporates all applicable air quality requirements. This includes emission limits and control technology standards from PSD (BACT) or NNSR (LAER and emission offsets) permits, as well as applicable NSPS and NESHAP standards for specific process units and equipment.

All of these elements are organized within the Title V permit, which establishes enforceable emission limits, monitoring, recordkeeping, and reporting requirements, as well as compliance certification obligations and unit-specific conditions or testing protocols. This umbrella structure provides a unified framework for regulatory compliance across the entire facility.

Permits by location

Permit requirements depend on whether a facility is located in an area that meets the National Ambient Air Quality Standards (NAAQS). These include:

• Attainment area NSR permits – Required for facilities located in areas that are in attainment with all NAAQS. This includes minor sources and major PSD facilities and major Title V facilities. For major downstream petroleum industry sources, these are typically individual air permits.
• Nonattainment area NSR permits required for facilities located in areas designated as nonattainment for one or more NAAQS pollutants. These permits are triggered for construction of a new major source of criteria air pollutants. The major source trigger depends on whether the area is classified as a marginal, moderate, serious, severe or extreme nonattainment area. These are individual air permits.  

States may offer permitting options such as permits by rule (PBRs), general permits, or individual air permits that can be used to permit smaller projects.

Permit by Emission Level

Permit Type	Typical PTE Threshold Triggering Initial Air Permit	Permit Major Modification Trigger
Title V Operating Permits	1. Equal to or greater than 100 tpy of any of VOCs, NOx, CO, PM2.5, PM10, or SO2.  2. Equal to or greater than 10 tpy of any one HAP. 3. Equal to or greater than 25 tpy of any combination of HAPs.	Not applicable
Prevention of Significant Deterioration (PSD) NSR permit – located in an Attainment Area	Petroleum refinery emitting equal to or greater than 100 tpy of any of VOCs, NOx, CO, PM2.5, PM10, or SO2 since they are one of EPA named 28 industry categories. GHGs if emissions exceed 75,000 tpy CO₂e at an existing PSD major source. PSD does not apply to HAPs. PSD facilities must also obtain a Title V operating permit.	Significant Emission Rates: Carbon monoxide (CO): 100 tpy Nitrogen oxides (NOₓ): 40 tpy Sulfur dioxide (SO₂): 40 tpy Particulate matter ≤10 µm (PM10): 15 tpy Particulate matter ≤2.5 µm (PM2.5): 10 tpy Lead: 0.6 tpy Volatile organic compounds (VOC): 40 tpy GHG: Increase of ≥ 25,000 tpy CO2e, and increase of ≥ 100 tpy GHG mass emissions
Nonattainment NSR Permit – located in a Nonattainment Area	Permitting trigger depends on whether facility is located in an area is classified as a marginal, moderate, serious, severe or extreme nonattainment area. Does not apply to HAPs. Nonattainment NSR facilities must also obtain a Title V operating permit. See link 3 below for permitting triggers.	Emission rates (tpy) that trigger project major modification permitting depends on the nonattainment air pollutant (O3, PM2.5, PM10, SO2) and nonattainment area classification (e.g., marginal, moderate, serious, severe, extreme). See link in Note 3 below.

1. Refinery HAPs include benzene, cumene, toluene, ethylbenzene, xylenes, n-hexane, 2,2,4-trimethylpentane
2. Link to USEPA initial HAP listing with modifications
3. Link to Nonattainment NSR major source thresholds and significant emission rates for major modifications

Air Permitting Process

Air permits for downstream petroleum facilities fall into preconstruction (New Source Review – PSD in attainment areas and Nonattainment NSR in nonattainment areas) and operating programs (federal Title V/Part 70 and any state-only operating permits). NSR requires proposed projects to apply appropriate controls and demonstrate protection of air quality before construction, while Title V compiles all applicable requirements for major sources of criteria pollutants and HAPs into a single operating permit.

Federal rules and guidance set the framework, but state environmental agencies administer almost all permitting through (State Implementation Plan) SIP-approved regulations.

Many states use a two-step process:

• Step 1 – NSR permit (preconstruction) that authorizes construction of the facility/project.
• Step 2 – Operating permit that authorizes ongoing operation and compiles all applicable requirements (Title V/Part 70 and state-only operating permits).

Other states use a combined permit that approves construction and operation in a single action, with the operating portion incorporating both federal and state requirements.

Both NSR and operating permit decisions are based on the representations in the application, including emission calculations, applicability determinations, control selections, monitoring, and proposed limits.

For an individual permit, the facility submits the required state application forms and technical support documents. The agency conducts completeness and technical reviews, may request additional information, and then prepares a draft permit for the applicant’s review. The draft permit typically undergoes public notice and comment and, where applicable, EPA review; significant comments can lead to revisions or a public meeting or hearing. After the notice/comment period is resolved and any issues are addressed, the agency issues the final permit, for NSR, for operation, or for both when combined.

Permits by rule and general permits (see description below) normally do not require a two step approval process and are not noticed for public comment with each application. Public notice and comment occurred when the rule or general permit was initially adopted and approved.

Air Permit Contents

The contents of an individual air permit varies by state but will commonly contain the following:

• Permit type (e.g., minor source, Title V, PSD, temporary/portable source)
• Facility permit #, ID#, company ID
• Facility contact and location information
• Facility process description
• Permit effective date
• Permit expiration date (if applicable)
• List of emission sources with permit limits on:
  • Emissions – criteria air pollutants, HAPs, GHGs
  • Operating rates (e.g., throughput, runtime, horsepower, capacity)
  • Flaring rate
• Emission Control Systems Analysis and Use
  • Best Available Control Technology (BACT) analysis for attainment area permits
  • Lowest Achievable Emission Rate (LAER) analysis for nonattainment area permits
• Offsets for NNSR permits.
• Applicable federal and state air quality regulations
• Insignificant activities (de minimis emissions)
• Maintenance, startup, and shutdown emissions that can include malfunction emissions.
• Air Dispersion Modeling Report
• Hazardous air pollution assessment – Maximum Achievable Control Technology (MACT) analysis

Public Notice Requirements for Major Air Permit Actions

Public participation is required by federal and state air permitting regulations for significant emission sources. Public notice and comment periods are mandated to ensure transparency, allow stakeholder input, and inform agency decisions. While specific procedures vary by state, the typical requirements include:

1. Notice and access: Agency publishes a public notice and the draft permit and supporting materials are made available locally (county location) and online.
2. Public comment period: Minimum 30 days for written comments.
3. EPA review: 45-day EPA review for Title V permits and for NSR permits often concurrent with public comment period .
4. Hearings: Held if requested by public representative or at agency discretion; advance notice required; oral/written comments accepted.
5. Response to comments: Agency issues written responses and may revise the draft.
6. Final permit & access: After comments are addressed, the permit is issued and all materials are made public; some programs allow administrative or judicial appeals.

Permit Modifications

Minor modifications

A minor modification is any project at a major source (PSD or NNSR) or minor source that does not meet the major-modification thresholds for the regulated NSR pollutant significant emissions increase. These projects are authorized under the state minor NSR program, which sets state-specific applicability thresholds, permit types, and notice requirements. Applicants use enforceable permit limits to remain below major thresholds.

Major modification (generic for PSD and NNSR).

At an existing major source (PSD or NNSR), a project is a major modification when it causes both a significant emissions increase and a significant net emissions increase (after project netting) of a regulated NSR pollutant. The applicable program depends on the area’s designation: in attainment/unclassifiable areas, PSD applies and requires BACT, a full air quality analysis (NAAQS, increments, and, where relevant, Class I/AQRVs), and public notice; in nonattainment areas, NNSR applies and requires LAER and procurement of emission offsets at the required ratio.

Cimarron Solutions Aligned with Permit Requirements

Refinery, bulk storage and product terminal permits require controls to meet VOC and HAP limits. Cimarron provides a full suite of emissions control technologies that meet these permit conditions and help maximize operational uptime, including:

• Thermal oxidizers, flares, and vapor combustion units
• Activated carbon based vapor recovery units (VRUs)
• Ultra Low NOx burners

For facilities subject to PSD and GHG permitting, Cimarron’s control technologies also support compliance with Best Available Control Technology (BACT) requirements for VOCs, HAPs, and GHGs—helping reduce emissions below permitting thresholds or ensuring control technologies meet regulatory expectations.

With Sytelink360®, operators get real-time visibility into control performance, streamlining compliance documentation and enabling faster response when conditions change. The platform helps ensure control devices remain within permitted limits and provides critical data for Title V and PSD recordkeeping.

Summary

State agencies administer day to day air permitting for downstream petroleum facilities such as refineries, tank farms, terminals, and loading racks within a federal framework that includes NSR (PSD/NNSR), Title V, and NSPS/NESHAP programs. Success depends on matching the project with the correct authorization—whether an individual permit, permit by rule (PBR), or general permit. It also requires ensuring that calculated emissions and applicability determinations align with the appropriate control strategy for air emissions. Effective permitting follows a structured workflow for application preparation: define processes and emission sources, quantify emissions, determine applicable regulations, select emission controls, and implement a reliable monitoring and compliance system.

Conclusions

Cimarron connects source-specific emissions estimates to field-proven control solutions: activated carbon VRUs or enclosed VCUs and thermal oxidizers for loading operations, high-reliability enclosed flares and flare systems, and ultralow NOx burners and oxidation technologies for combustion sources. These systems are supported by LDAR programs and Sytelink360® monitoring to ensure that emission limits, testing, recordkeeping, and reporting withstand public notice, EPA review, and air permit compliance requirements.

Need help interpreting your air permit or selecting the right emissions control system? Cimarron offers industry leading solutions backed by regulatory expertise. Contact our team to schedule a consultation or learn more about how our technologies can support your air permitting and compliance strategy.

Visit our website at Cimarron.com or call us at 1 (844) 746-1676.