Guidance for Conducting Air Quality General Conformity Evaluations

EPA’s General Conformity Regulations, at 40 C.F.R. Part 93, implement the CAA’s provisions that prohibit federal agencies from taking actions that may cause or contribute to violations of the National Ambient Air Quality Standards (NAAQS). This IM provides guidance to BLM staff and contractors on complying with these requirements for BLM actions and authorized activities in nonattainment and/or maintenance areas and provides specific guidance for oil and gas actions in Attachment 3.  

This IM describes the process and explains options available under EPA’s General Conformity Regulations to demonstrate that the federal actions being considered will not cause or contribute to a new violation of the NAAQS or worsen existing violations. The intent of the general conformity requirement is to prevent potential air quality impacts of federal actions from causing or contributing to a new violation of the NAAQS, increasing the frequency or severity of existing violations, or interfering with the purpose of a state, tribal or federal implementation plan (SIP, TIP, or FIP). In the CAA, Congress recognized that actions taken by federal agencies could affect state, tribal, and local agencies’ ability to attain and maintain the NAAQS. In Section 176(c)) of the CAA, Congress established requirements to ensure that federal agencies’ proposed actions conform to the applicable implementation plan for attaining and maintaining the NAAQS. 42 U.S.C. § 7506. That section requires federal entities to determine whether the emissions from a federal action will conform to the purposes of the SIP or interfere with the ability of the state or tribe to attain and maintain the NAAQS. These requirements are codified in the General Conformity Regulations at 40 C.F.R. §§ 93.150 et seq. 

Conformity Evaluations  

All federal actions within a nonattainment or maintenance area that have the potential to emit NAAQS pollutants or their precursors for which the area has been designated nonattainment must be evaluated to determine whether the emissions from such actions conform to the applicable SIP or conformity must be demonstrated through other options. A federal action refers to any activity directly engaged in by a department or agency of the Federal Government. It also refers to any activity that a department or agency supports in any way, which includes providing financial assistance, licenses, permits or formal approval (40 C.F.R. § 93.152). Agencies must calculate the total direct and indirect emissions for the action using approved emissions models and methodologies, such as those found in EPA’s AP-42 emission factors and the Motor Vehicle Emissions Simulator (MOVES). BLM air resource specialists have developed emission calculators that use approved methodologies and can be used in general conformity evaluations (e.g., Integrated Air Resource Tools, Emissions Modeling Inventory Tool). 

The regulations provide a three-step process for meeting the general conformity requirements of the CAA. These are: 

1. Applicability Analysis 

2. Conformity Determination 

3. Agency and Public Review Process 

Each of these steps are described in detail below. 

Applicability Analysis 

The applicability analysis should be a simple analysis to assess whether a conformity determination is needed. Consider analyzing all proposed federal actions early to facilitate a comparative evaluation of alternatives in any National Environmental Policy Act (NEPA) document with respect to air quality issues. However, the more detailed conformity determination, if necessary, will only evaluate the preferred alternative identified in the applicable NEPA document.   

Federal actions must be evaluated for conformity if they occur in designated nonattainment or maintenance areas for any NAAQS pollutant. Under 40 C.F.R. § 93.153(b), the applicability analysis must consider whether the total direct and indirect emissions caused by the proposed action would exceed established de minimis thresholds for the relevant pollutants. If the action occurs entirely outside of a nonattainment or maintenance area and does not cause emissions within such areas, a conformity determination is not required. However, if emissions from the action are reasonably expected to occur within a nonattainment or maintenance area, the analysis must proceed to determine whether the action is exempt, clearly de minimis, or presumed to conform. To determine whether emissions are reasonably foreseeable, the BLM should consider whether there is a clear causal relationship between the federal action and the resulting emissions. Document the rationale for determining whether emissions are reasonably foreseeable, especially in cases where the connection between the action and the emissions is less direct. This documentation should be included in the administrative record and can help support the applicability analysis and any subsequent conformity determination, if required. 

Certain federal actions are exempt from conformity requirements under 40 C.F.R. § 93.153(d). These are set out in Attachment 1 and include actions, such as routine maintenance and repair activities, administrative actions, and planning or feasibility studies that do not result in emissions. Additionally, actions that are clearly de minimis under 40 C.F.R. § 93.153(c), meaning their emissions are well below the applicable thresholds, do not require a conformity determination. These actions may include small-scale construction, land transfers, or other minor activities. Some actions may also be “presumed to conform” under 40 C.F.R. § 93.153(h), which means they are expected not to exceed de minimis levels based on prior analysis and documentation. 

The presumed-to-conform provision under 40 C.F.R. § 93.153(h) allows federal agencies to streamline the applicability analysis for routine or recurring actions that consistently result in emissions below de minimis thresholds or that do not interfere with attainment or maintenance of air quality standards. Agencies may develop a list of such actions and submit it for inclusion in a SIP, as authorized under 40 C.F.R. § 51.851(f). The state or tribe may impose limitations on the list and must demonstrate that the listed actions will not interfere with timely attainment or maintenance of the NAAQS, reasonable further progress milestones, or other CAA requirements. Alternatively, under 40 C.F.R. § 93.153(g), a federal agency may independently establish a list of presumed-to-conform actions without incorporating it into a SIP according to criteria in 40 C.F.R. § 93.153(h). Creating a presumed-to-conform list, either independently or in coordination with a state, tribe, and EPA, can significantly reduce the administrative burden and streamline project-level air quality reviews.  

For actions that are not specified as clearly de minimis, exempt by regulation under 40 C.F.R. § 93.153(c) and (d), or presumed to conform, agencies must evaluate whether the total direct and indirect emissions increase from the action are de minimis or not. Attachment 2 (Criteria Pollutant Rates that Apply in Nonattainment and Maintenance Areas) shows de minimis annual emission thresholds for criteria air pollutants and precursors emitted in nonattainment and maintenance areas based on the severity. Direct emissions are those that are caused or initiated by the federal action, originated in a nonattainment or maintenance area, occur at the same time and place as the action, and are reasonably foreseeable (40 C.F.R. § 93.152). Indirect emissions are caused or initiated by the federal action and are reasonably foreseeable but occur at a different time or place as the action but still within the same nonattainment area. Additionally, indirect emissions are those that the agency can practically control and for which the agency has continuing program responsibility (40 C.F.R. § 93.152).  

An applicability analysis demonstrates and documents that the action is exempt or has emissions below the de minimis thresholds. Federal actions that are exempt or turn out to be below the de minimis threshold do not require a public review process or regulatory agency notification beyond what may be required for NEPA. This evaluation should be included in the administrative record for the associated NEPA analysis. If, through the applicability analysis, the proposed federal action is expected to exceed the de minimis levels for criteria pollutants for which the area was designated as being in nonattainment, the BLM must then prepare a conformity determination before the action can be authorized or allowed to proceed. 

In summary, the applicability analysis considers these factors: 

1. Does the action occur inside a nonattainment or maintenance area? 

2. Does the action produce emissions of the pollutant or precursor pollutants for which the area is in nonattainment? 

3. Is the action exempt by regulation, refer to 40 C.F.R. § 93.153(d)? (e.g. emergency response, covered by major or minor New Source Review permit, etc.) 

4. Is the action covered by transportation conformity and conformity was demonstrated under the Transportation Conformity Rules, refer to 40 C.F.R. Part 93 Subpart A? 

5. Is the action included in a presumed-to-conform list, such as in 40 C.F.R. § 93.153(c), a SIP for the nonattainment or maintenance area, or in the federal agency developed presumed to conform list? 

6. Are the reasonably foreseeable total direct and indirect net annual increase in emissions below de minimis rates (Attachment 2)? 

If the proposed action is exempt or below de minimis thresholds, include a brief discussion of the applicability analysis in the Environmental Assessment or Environmental Impact Statement and skip the agency and public review step to complete the process. If the proposed action is not exempt or below de minimis levels, proceed to the conformity determination. 

Conformity Determination 

The general conformity determination must be a separate analysis, and for BLM purposes, should generally be conducted concurrently with the NEPA analysis to ensure that the project meets all applicable regulations (DOI NEPA Handbook, Section 3.8). Conformity determinations are only required for the preferred alternative. 

In states that have SIPs, the SIP will identify provisions that may include an emissions inventory for the nonattainment area, an emissions budget for future actions, application of emissions control measures, and/or a modeling demonstration showing control measures to help bring the area back into compliance with the NAAQS. Where SIP provisions exist, they can be incorporated into the appropriate sections of any NEPA document the BLM prepares for the proposed federal action. In some cases, a determination can be straightforward, with the federal agency only having to document the information in the SIP where the total direct and indirect emissions caused by the action are specifically identified (40 C.F.R. § 93.158(a)(1)). Where emissions are not specifically identified in the SIP but included in an emissions budget category, the federal agency can demonstrate conformity by having the applicable regulatory agency provide a written statement documenting that those emissions from the federal action will not exceed the emissions budget in the SIP. In the absence of an approved SIP, such as for marginal nonattainment areas, the BLM options for demonstrating conformity are limited. The primary options for demonstrating conformity in the absence of a SIP are to modify the proposed action to achieve emissions below de minimis levels, fully offset emissions within the same nonattainment or maintenance area 40 C.F.R. § 93.158(a)(2), perform modeling that shows that the action does not cause or contribute to new violations of the NAAQS, 40 C.F.R. § 93.158(b), or secure a commitment from the regulatory agency to include emissions from the federal action in a future SIP revision. 

There are several methods for demonstrating conformity when the net emissions increase is equal or exceeds de minimis rates. Federal agencies can choose one or a combination of the criteria for demonstrating conformity under 40 C.F.R. § 93.158. Not all methods are applicable for every pollutant or specific nonattainment areas so the BLM should consult with the State and EPA to identify the approach that will work best for the project. The different methods are as follows: 

• Demonstrate that the total of direct and indirect emissions from the action are specifically identified and accounted for in the applicable SIP. 

• Demonstrate that the total of direct and indirect emissions from the action, along with all other emissions in the area, do not exceed the emissions budget specified in the SIP. 

• Secure a commitment from the State, Tribe, or EPA to include the emissions in a future implementation plan revision. 

• Demonstrate that the total of direct and indirect emissions, not just those above the de minimis threshold, of directly emitted pollutants or precursors from the action are fully offset within the same nonattainment or maintenance area. Emissions offsets must be quantifiable, surplus (i.e., not already required by the SIP), enforceable, and permeant. Conduct air quality modeling to demonstrate that the action does not cause or contribute to new violations of the NAAQS or increase the frequency or severity of existing violations. Modeling of ozone is not currently allowed by the EPA to demonstrate conformity. 

• Modify the proposed action to achieve emissions reductions.  

Regardless of the criteria and methods used, the demonstration must support a positive conformity determination by offsetting, mitigating, or otherwise reducing the net increase in emissions to zero. 

Agency and Public Review Process 

The NEPA document should clearly identify how the BLM has met the requirements for a conformity assessment or determination (DOI NEPA Handbook 3.8(c)). In the development of a finding of no significant impact, the BLM is required to consider effects on public health and safety which includes air quality. This includes consideration of the relationship of effects to established regulatory thresholds (DOI NEPA Handbook, Appendix 3, 6(3)). The need to complete a conformity assessment does not equate to a determination of significance.  

If a federal action is determined not to conform to the applicable SIP, even though the NEPA process has been completed, the federal action cannot be authorized or implemented. Finally, application of a categorical exclusion for NEPA compliance does not exclude federal action from compliance with EPA’s General Conformity Regulations.