Emission Standards ) 51 of the CAA. Therefore, although aircraft HAPs ar e not specifically regulated under the CAA, they are indirectly controlled as elements of total hydrocarbons (HC) and PM. 

In a related matter, the EPA has identified 21 HAPs that are designated as Mobile Source Air Toxics (MSATs) 52 to signify those HAPs that are emitted by motor vehicles and non- road engines (e.g., farm and construction equipment, heavy industrial vehicles, GSE, etc.). These pollutants include VOCs and heavy metals that are commonly associated with the combustion of gasoline and diesel fuels - including those emitted by aviation-related motor vehicles and GSE. 

Other sources of HAPs associated with airports are similarly regulated under Section 112 of the CAA if their emissions exceed established thresholds and they meet the definition of a major stationary or area source. These may include aircraft repair and maintenance facilities, engine test cells, central heating plants, painting operations, and other airport support services generate air emissions. 

## 6.2.2. FAA Guidance 

In 2003, the FAA undertook a review of publicly available information pertaining to relationship(s) between aircraft and airport-related activities and the emissions of HAPs. This initial body of work focused on those emissions specifically identified by the EPA as HAPs and was prepared in response to the rising interest by various federal, state and local governmental agencies and the general public in connection with these pollutants. Referred to as the FAA Resource Document for HAPs , this initial report was entitled and is described as follows: 

• Select Resource Materials and Annotated Bibliography on the Topic of Hazardous Air Pollutants (HAPs) Associated With Aircraft, Airports and Aviation. 53 

Among the key findings from this initial publicatio n was the need for a more unified approach and technical guidelines for evaluating HAPs emissions for aviation-related sources. Other topics include HAP types and sources, agency regulations, and monitoring data associated with airports and aviation. 

In response to this need for more information, in 2009 the EPA and the FAA developed organic gas (OG) speciation profiles and best practices for use in HAPs emission inventories of aircraft equipped with turbofan, turbojet, and turboprop engines fueled with kerosene-based jet-A fuel. The development of these profiles and guidance was the combined work of both agencies, taking into account the most recent data and information available. Referred to as the Speciated Organic Gas Emissions from Aircraft Guidance , this document is entitled and described follows: 

