## 1. Introduction and Background 

This section discusses the purposes for which this Aviation Emissions and Air Quality Handbook (the Handbook ) was prepared, the intended audience, its primary objectives, and its contents. 

## 1.1. Purpose of This Handbook 

This Handbook has been published by the Federal Aviation Administration (FAA) explanatory guidance, and is a tool and resource designed to assist the FAA and others that are responsible for the planning, organization, and completion of air quality assessments aviation-related projects and/or actions. Following the guidance in this Handbook will help to ensure that air quality assessments for these projects/actions are comprehensive, consistent, and appropriate for use in the disclosure and decision-making processes. 

The effects on air quality from aviation and aviation-related developments and operations have long been an important and significant subject matter. On one hand, airports perform vital civic and economic functions by serving scheduled and unscheduled operations of air carriers which enable the transportation of passengers and cargo safely and efficiently across the count ry and throughout the world. For over 100 years, airports (including general aviation [GA] airports) have remained among the enabling resources for progress and prosperity within the communities they serve. On the other hand, air pollutants associated with aircraft and other airport emission sources are an inevitable consequence of these activities and can have impacts on local and regional air quality. 

This long-term connection between aviation and air quality has been growing in im portance as the aviation industry seeks to (i) develop, expand, and/or improve their facilities, equipment, and procedures; (ii) repair /replace aging infrastructure; and/or (iii) accommodate the forecasted growth in air traffic; while implementing sustainable practices. Meanwhile, air quality regulatory agencies continually strive to safeguard human health and the natural environment from effects of air pollution – including the air emissions associated with aviation. 

Historically, the junction where aviation and air quality most often intersect s is in the federal Clean Air Act (CAA) and other environmental-related regulations and directives which are often discussed in environmental documents prepared in accordance with the National Environmental Policy Act (NEPA) (discussed in greater detail in Section 2 , Regulatory Framework ). In short, such rules and requirements mandate that the air quality impacts associated with federal actions and projects do, in the case of the CAA, not cause, or worsen, violations of relevant air quality standards, criteria and/or thresholds and environmental impacts are disclosed under NEPA to the public. 

For the FAA, these demonstrations of disclosure and compliance for air quality are regul arly accomplished in conjunction with the more encompassing environmental analyses of aviation- related projects/actions conducted under NEPA as part of Environmental Assessments Environmental Impact Statements (EA s/EISs) and/or in association with General Conformity Determinations performed under the CAA. In many cases, the air quality analysis is an integral component of these assessments. Therefore, in support of the documentation of these air quality assessments, the purpose of this Handbook is essentially three-fold: 

