Skip to content U.S. Department of Transportation/Federal Highway AdministrationU.S. Department of Transportation/Federal Highway Administration

Office of Planning, Environment, & Realty (HEP)
PlanningEnvironmentReal Estate

HEP Events Guidance Publications Awards Contacts

Guidance for Qualitative Project Level "Hot Spot" Analysis in PM-10 Nonattainment and Maintenance Areas

Questions and Answers

What are the analytical requirements for assessing the impacts of projects in PM-10 nonattainment and maintenance areas?

Section 93.116 of the transportation conformity rule states that any project-level conformity determination in a PM-10 nonattainment or maintenance area (see Figure 1) must document that no new local PM-10 violations will be created and the severity or number of existing violations will not be increased as a result of the project. Since EPA has not released modeling guidance on how to perform quantitative PM-10 hot-spot analysis, such quantitative analysis is not currently required (40 CFR 93.123(b)(4)). However, if a quantitative analysis is not done, the demonstration required by 40 CFR 93.116 must be based on a qualitative consideration of local factors (40 CFR 93.123(b)(2)).

A reasoned and logical explanation of why a hot spot will not be created or worsened is to be provided for project-level conformity determinations. This guidance provides examples of how to develop a hot-spot analysis, but other methods would also be acceptable. The interagency consultation process must be used to evaluate and decide on the methods and assumptions for conducting hot-spot analysis (40 CFR 93.105(c)(1)(i)).

What projects are subject to PM-10 qualitative hot-spot analysis?

A transportation project is subject to PM-10 hot-spot qualitative analysis requirements if it is:

Interagency consultation must be undertaken to identify which projects require PM-10 qualitative hot spot analyses.

What are the roles and responsibilities of different agencies in project-level conformity determinations?

Roles and responsibilities of different agencies for meeting the transportation conformity requirements are addressed in either 40 CFR 93.105 of the Federal conformity rule or in a State's EPA-approved Conformity State Implementation Plan (SIP). In general, the following agencies have these responsibilities in implementing the PM-10 hot-spot analysis requirement.

  1. Project Sponsor - The project sponsor is the agency responsible for implementing the project. Typically, the project sponsor is a local government, transit operator, metropolitan planning organization, or State department of transportation. The project sponsor is responsible for providing the PM-10 qualitative analysis addressed in this guidance and meeting consultation requirements described in 40 CFR 93.105 or the approved Conformity SIP. Consultation with State and/or local agencies is critical to completing qualitative hot-spot analyses. The project sponsor, in cooperation with the Federal Agency, also is responsible for conducting the environmental analysis and review to comply with the National Environmental Policy Act (NEPA) of 1969 as required by the CEQ regulations (40 CFR 1500-1508) and the FHWA/FTA project development requirements (23 CFR Part 771).

  2. FHWA/FTA - FHWA and FTA are jointly responsible for determining that the requirements of the Transportation Conformity Rule are met. The determination of whether the PM-10 project level qualitative analysis requirements have been met generally occurs through the interagency consultation process. Documents prepared to meet the requirements of NEPA (40 CFR 1500-1508) and 23 CFR Part 771 are used to demonstrate that the analysis has been appropriately conducted. These documents may include Environmental Impact Statements (EISs) with Records of Decision (RODs) and Environmental Assessments (EAs) with Findings of No Significant Impacts (FONSI). The analysis may be appropriate for Categorical Exclusions (CEs) determinations. It is the responsibility of FHWA/FTA to review and approve EISs, RODs EAs, FONSIs, and CEs for certain actions.

  3. EPA - EPA plays an advisory role in the conformity determination process. As a matter of course, FHWA/FTA consult with EPA before making a final conformity determination.

What analysis years should be used in hot-spot analyses?

In the preamble of an amendment to the conformity rule published April 10, 2000, EPA clarifies its policy concerning the horizon years to be used in a hot-spot analysis (65 FR 18914). As discussed in that rulemaking, the transportation conformity rule provides areas with flexibility to decide how to demonstrate that hot-spots are not caused or worsened in an area through the interagency consultation process, as appropriate to the individual area, on a case-by-case basis. Although most areas conduct hot-spot analyses for the year of project completion, many areas also examine other analysis years in the future. For example, some areas may analyze the last year of a currently conforming transportation plan, or another year within the timeframe of that plan, whichever year emissions are expected to be the highest. In any case, the hot-spot analysis should examine the year in which peak emissions in the project area are expected, which may not necessarily be the last year of the conforming plan. For more discussion on this issue, see the preamble to the April 10, 2000, final rule (65 FR 18914).

What are the criteria for meeting project level hot-spot analysis?

The conformity rule specifies that FHWA/FTA-funded or approved projects in PM-10 nonattainment and maintenance areas must not cause or contribute to any new localized PM-10 violations or increase the frequency or severity of any existing PM-10 violations within the project's area. The hot-spot analysis is intended to assess possible violations due to the project in combination with changes in the background levels over time. If there are no current exceedances or violations in the area affected by the project, the project's future effect is compared to the standard since the test is whether the project causes a new violation (i.e., the project's effect causes an exceedance of the standard). If there are current violations or exceedances in the area affected by the project, the project cannot worsen an existing violation, so a qualitative no-build/build comparison is required at a minimum.

Hot-spot analyses must include the entire project and may be performed only after the project's major design features have been identified. Preferred project alternatives must be compared to a no-build alternative in either a conceptual or more technically rigorous way. In performing the hot spot analysis, the design concept and scope of the project must be consistent to that included in the transportation plan and transportation improvement program. Any significant change in project design or scope will require a reevaluation of regional emissions and a new qualitative hot-spot analysis. However, if there are no localized violations, and if there would not be any violations within the project area, the project clearly satisfies this criterion.

Hot-spot analyses are not required to consider temporary increases in emissions caused by construction related activities that last 5 years or less at any individual site (40 CFR 93.123 (c)(5)).

What is the definition of a new violation?

The consultation process should be used to determine if new violations are anticipated under the hot-spot analyses. As implied, a new violation is one where concentration levels are expected to be higher than the PM-10 standard in a localized area that has not previously demonstrated such levels. It can and should be distinguishable from an exceedance registered by an existing, nearby monitor that is not caused by the project. As discussed in the preamble to the November 24, 1993, conformity rule, "EPA believes that a seemingly new violation may be considered to be a relocation and reduction of an existing violation only if it were in the areas substantially affected by the project and if the predicted design value for the new site would be less than the design value at the‘old' site without the project, i.e., a net air quality benefit." (58 FR 62213).

What are some of the factors to consider in describing existing conditions?

An accurate description of existing conditions and factors that may influence PM-10 levels in the area affected by the proposed project should be provided. Analysis of those conditions, and how they are projected to change over time with the addition of the proposed project is the basis of the project-level conformity determination. Factors to be considered include:

  1. Area affected by the proposed project. Describe the geographic area and general air quality conditions that could be influenced by the project, focusing specifically on PM-10 levels.

  2. Existing Conditions. While the following list is not intended to be exhaustive or prescriptive, factors that are relevant to PM-10 levels may include:

    1. Air Quality. Determine if a monitoring station is near the project that will provide data on local air quality conditions, including PM-10 emissions. Also, consider reviewing data from monitoring stations located in other areas that may have similar traffic or environmental conditions.

      Source:
      1. State/local areas similar to the project area. This review may be useful to evaluate and better understand the effects of the project.

      2. Monitoring data and modeling results included in SIP and more recent monitoring data from State/local air agencies; State/local public health departments.

    2. Transportation and traffic conditions. Address modes, volumes, speed, congestion, trends, etc. When the project analysis is incorporated in a NEPA document, this description should largely reference other sections of the NEPA document that address traffic and transportation issues in greater depth. A brief summary description of transportation and traffic conditions may be appropriate.

      Source: Project sponsor and observation.

    3. Built and natural environment, as they relate to PM-10. This description would include whether the character of the area is urban or rural, and whether adjacent buildings or topography create barriers to dispersal of PM-10. Relevant development trends and land use patterns should be addressed if they have a bearing on potential PM emissions from the project.

      Source: Project sponsor, local planning agency, and observation.

    4. Meteorology, climate and seasonal data relevant to PM-10 emissions. Address whether the area experiences atmospheric "inversions," prevailing wind direction and speed, and amount of seasonal rainfall which have an impact on the prevalence of PM concentrations.

      Source: State/local air quality agencies; National Weather Service.

    5. Transportation control measures (TCMs) or adopted emission control programs in the project area that may mitigate any potential increase in PM emissions or that may be affected by the proposed project. The impact of national rules and regulations that EPA has promulgated, such as heavy-duty diesel rules, that are currently being implemented should also be considered.

      Source: State or local air agency, EPA; review the applicable PM-10 SIP.

    6. Other factors as appropriate.

What factors may be considered in describing "future" scenarios for projects?

The following factors may be used to describe the "future" scenarios2. These factors will change in the future, including the design year for the project, and whether these would expect to result in increases or decreases in PM-10 levels. Examples of factors that may lead to changes in PM-10 levels in the project area include:

Each future build scenarios should consider whether the project would be expected to increase or decrease PM-10 concentration levels in the project area. This analysis should address whether the build alternative(s) would be expected to result in an exceedance of the PM-10 standard, or affect existing violations. As noted before, the temporary increase in emissions resulting from construction related activities of the proposed project that last 5 years or less does not need to be considered in the hot-spot analysis.

What are the possible measures to mitigate an increase in PM-10 concentrations?

Where the project may lead to an increase in PM-10 levels, measures to mitigate these impacts should be addressed. In these cases, written commitments for project-level mitigation or control measures must be obtained from the project sponsor and/or operator prior to making a project-level conformity determination (40 CFR 93.125(a)). Options to reduce localized PM-10 emissions are included in the Appendix.


1 The conformity rule does not require quantitative analyses. However, if an area has conducted a quantitative analysis, a qualitative analysis does not need to be done.

2 Future scenarios include "Future Without the Project" (the "No-Build Alternative") and "Future With the Project" ("Build Alternative(s))"

Updated: 07/06/2011
HEP Home Planning Environment Real Estate
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000