Addressing Air Quality Issues in the NEPA Process for Highway Projects Practitioner’s Handbook

This handbook is intended to assist practitioners in addressing air quality issues, including transportation conformity requirements, as part of the National Environmental Policy Act (NEPA) process for highway projects. The handbook summarizes key requirements under NEPA and the Clean Air Act and provides advice for documenting compliance with the Clean Air Act requirements as a part of the NEPA process.

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Air Quality & Transportation

Transportation programs and practices often impact air quality in our communities.

We dive deep into Air Quality issues and how problems can be mitigated in transportation planning.


Near-Road Air Quality: Insights from a U.S. DOT Five-Year Transportation Pooled Fund Study

Research shows that substantial traffic, especially diesel-powered trucks and buses, can create pollution hot spots within a few hundred meters of major roads. In recognition of the importance of addressing near-road air pollution, eight state and federal agencies pooled their research efforts on the topic, obtaining and evaluating an unprecedented amount of near-road air quality data. TR News is copyright, National Academy of Sciences, Engineering, and Medicine; posted with permission of the Transportation Research Board.”

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Near-Road Air Quality Pooled Fund Reports

Interested in learning more about the insights above? Read all of the reports that resulted from the near-road air quality pooled fund project and take a look at additional peer-reviewed articles that stemmed from the research.

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Community of Practice

The purpose of the Air Quality COP is to assemble a group of State Department of Transportation (DOT) air quality practitioners to have a focused discussion on the state of the practice, emerging issues, and research data needs on particular air quality issues.

External Links

Air Quality Fundamentals Video Series (2016), Developed by TRB, FHWA and AASHTO.

NCHRP 25-25, Task 89 – Establishing Representative Background Concentrations for Quantitative Hot-spot Analyses for Particulate Matter: Final Report, Case Studies, Power Point (2014)

NCHRP 25-25, Task 78 – Programmatic Agreements for Project-Level Air Quality Analyses Using MOVES, CAL3QHC/R and AERMOD (2015): Project Description including Final Report, Appendix B: Programmatic Agreement Template, Appendix C, Technical Support Document Template, and Data Files

NCHRP 25-25, Task 71 – Templates for Project-Level Analyses Using MOVES and AERMOD (2012): Final Report and Draft Templates

NCHRP 25-25, Task 70 – Assessment of Quantitative Mobile Source Air Toxics in Environmental Documents (2012): Final Report

NCHRP 25-25, Task 59 – Evaluate the Interactions Between Transportation-Related Particulate Matter, Ozone, Air Toxics, Climate Change, and Other Air Pollutant Control Strategies (2010): Final Report

NCHRP 25-25, Task 58 – Methods to Address Greenhouse Gas Emissions from Transportation Construction/Maintenance/Operations Activities (2010) Final Report and the Greenhouse Gas Calculator for State Departments of Transportation (GreenDOT) spreadsheet-based tool (.xls)

NCHRP 25-25, Task 42 – Determine Alternative Calculations for Fine Particulate Emission Factors Other Than AP-42 Applicable to Calculate Re-entrained Dust on Transportation Projects (2008): Final Report, User Guide

NCHRP 25-25, Task 18 – Recommended Approaches to Communicating Air Toxics Issues and Transportation Project-Related Analyses in NEPA Documents (2007): Final Report