Aviation Emissions and Air Quality Handbook  4.1.1.  Step 1: Determine the Need for the Assessment  The initial step in the process is aimed at determining when an air quality assessment is required.  As previously discussed, air quality assessments for  project/action may be necessary for  compliance with the requirements of NEPA, the CAA, and other environmental regulations and  directives. In addition, some states and/or local areas have air  quality requirements that may also pertain to airports. Therefore,  this section provides guidance on determining whether or not an  air quality assessment is appropriat e. Note that an air quality  assessment does not necessarily require creating an emissions  inventory or doing dispersion modeling. See Section (4.1.2  (“Step 2: Select the Assessment Methodology ”) for types of air  quality assessments.  In most cases, the need to conduct an air quality assessment  for  FAA-supported projects or actions  is project-specific, based  largely on the consideration of  various factors that, taken  together, help to formulate the overall decision-making process.  For ease of understanding, several of these factors are identified  in  Figure 4-2  ( Determine the Need for the Assessment ) and  explained further below. Importantly, this information intended to be used in conjunction with  Figure 4-3  ( Air Quality  Assessment Decision Flow Diagram ) as a means of simplifying  the decision-making process.  Step 1.A. Project/Action Definition  – The purpose of this step  is to define the scope of the proposed project (or action), as well  as the alternatives . This basic information provides necessary knowledge required in subsequent steps to determine when an air quality assessment is warranted and what  type of assessment should be conducted. Such information may  comprise (but is not limited to) th e proposed changes in the  airport layout, supporting facilities and infrastructure, and/or the  airport/aircraft operational characteristics. Ideally, the project  sponsor’s planning process will provide the information documentation needed to obtain these details.  Step 1.B. Determine FAA’s Involvement  – This step is to  establish whether or not FAA involvement ( e.g., approval,  funding, permitting, etc.) is associated with the project/action. In  those cases where FAA involvement is not required, an quality assessment for FAA purposes would not be necessary (as  there is no FAA action to  assess or disclose), but CAA, state/local, and other  environmental regulations and directives may still require an air quality assessment.  Furthermore, such projects/actions may still be subject to NEPA review , depending on  policies and procedures of the project/action sponsor . For example, a proposed roadway  interchange or private parking facility located off airport property does not require FAA  20$_{ }$ Figure 4-2. Step 1. Determine Need for the Assessment  1.A. Define  Project/Action  1.B. Determine if FAA  Involvement is  Required  1.C. Determine if  Project/Action Will  Increase Emissions  1.D. Determine  Attainment/Non- attainment Status  1.E. Assess  Agency/Public Scoping Comments 