Project Development - Air Quality

Project Development - Air Quality

Project Level Transportation Conformity

Atypical Events Documentation
There may be circumstances where a nearby background air quality monitor is influenced by atypical circumstances.  When this occurs a supplemental analysis will be required. A few examples are provided below.  

  • Establishing Representative Background Concentrations for Quantitative Hot-spot Analyses for Particulate Matter (NCHRP 25-25/Task 089)
  • Atypical Events Report State Route 202L (Santan Freeway) from Val Vista to Interstate 10 (ADOT Project Example)

Air Quality Conformity Regulations
These federal regulations cover the legal consultation and methodology requirements on air quality conformity, and the criteria/procedures for violations. Only applicable in Nonattainment and Maintenance Areas.

PM Hot-spot Analyses: Frequently Asked Questions
This Environmental Protection Agency (EPA) document describes the type of projects that need a quantitative PM hot-spot analysis. Please contact Environmental Planning Air Quality staff for interagency consultation requirements. 

2023 FHWA Carbon Monoxide (CO) Categorical Hot-Spot Finding
(January 2023) – FHWA's 2023 carbon monoxide (CO) categorical hot-spot finding per the transportation conformity rule at 40 CFR 93.123(a)(3) for highway projects that include one or more intersections in CO maintenance areas.   Please contact Environmental Planning Air Quality staff for information on the appropriate level of CO analysis for all projects.

Project Exemption List
This list consist of projects that are exempt from conformity to transportation plans and TIPs.

Transportation Conformity: A Basic Guide for State and Local Officials, FHWA Guidance FHWA-HEP-17-034

Quick Reference Guide For Transportation Planners/Engineers: Generating Traffic & Activity Data for Project-Level Air Quality Analyses 
This quick reference guide is intended to assist traffic analysts who work with traffic data and models in providing the traffic data required for emissions modeling and air quality analysis for transportation projects. It is intended as a supplement to National Cooperative Highway Research Program (NCHRP) Report 765, Analytical Travel Forecasting Approaches for Project-Level Planning and Design.

NEPA Air Quality

Mobile Source Air Toxics Guidance
This guidance helps the practitioner evaluate the mobile source air toxics on ADOT's highway improvement projects.

FHWA Green House Gas (GHG) Resource
This Federal Highway Administration website provides guidance on how to address Climate Change in NEPA documents.

Addressing Air Quality Issues in the NEPA Process for Highway Projects
This handbook was developed by the American Association of State Highway and Transportation Officials (AASHTO) to assist practitioners in addressing air quality issues in the NEPA process required under the clean air act. Please use this as a guide for developing the necessary NEPA air quality reports for ADOT projects.

  • ADOT has developed a draft report outline, please contact ADOT on required elements in report prior to use as project requirements vary.