Technical guidance on assessing impacts to air quality in NEPA and planning documents

National Park Service, NRPC Air Resources Division

Document Purpose:This paper provides an overview of approaches to assess impacts to air quality and resources affected by air pollution. It specifically applies to projects assessed under the National Environmental Policy Act (NEPA) and other planning initiatives affecting the National Park System. This technical air quality guidance for park staff, and technical specialists is intended for use in developing initial air pollution emissions estimates, determining the appropriate level of air quality analysis, assessing whether air pollution impacts are likely, and describing the degree and severity of those impacts to resources in National Park System units. It identifies technical air quality modeling and analysis tools and information resources that are available to conduct air quality impact assessments on park resources. This guidance is also intended to provide National Park Service (NPS) managers with air quality information for consideration when assessing compliance with the no-impairment mandate of the NPS Organic Act (NPS Management Policies 2006; Section 1.4.5). This guidance was developed to facilitate assessment of air pollution impacts to natural resources on NPS lands. While approval of projects generating air pollutants within National Park System boundaries is within the purview of the NPS, it is acknowledged that many of the pollution sources affecting parks are located outside park boundaries. For these projects NPS staff can work with other agencies, industries, or groups with project approval oversight to communicate impact and impairment concerns. While this document provides guidance on determining impairment under the NPS Organic Act, it does not establish a “bright line” for the amount of air pollution or air quality impacts which are acceptable or unacceptable. It is clearly inappropriate to consider all actions that fail to rise to the level of impairment as desirable or even acceptable. National Park System units are not “managed to” the threshold of being impaired. On the contrary, they are managed with the intent of being fully functional landscapes, worthy of being considered “special places” to the American people. This document is subject to revision in the future as additional planning guidance is developed within NPS. Material in this technical guidance has been adapted from an earlier document, Interim Technical Guidance on Assessing Impacts and Impairments to Natural Resources (NPS 2003). The 2003 interim guidance document also encompasses other natural resources of concern (e.g., biological, geologic, watersheds, lightscapes, soundscapes, and ecosystems). The policies and recommendations contained within this document are only intended to facilitate the decision making process for evaluating the severity of air quality impacts from internal and external activities, and improve the internal air resources management of the NPS. These policies and recommendations are not intended to, and do not, create any right or benefit, substantive or procedural, enforceable at law or equity by a party against the United States, its departments, agencies, instrumentalities or entities, its officers or employees, or any other person.

Technical guidance on assessing impacts to air quality in NEPA and planning documents

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