6.2.3.  HAPs Emission Inventory Methods  Aviation Emissions and Air Quality Handbook  Again, it is important to acknowledge that there are currently no  federal regulatory guidelines  specific to HAPs emissions from aircraft engines, specifically, and airports, in general. While the  methodology discussed in this  Handbook  is useful for disclosure, reporting, and comparative  purposes, it does not provide results that are directly comparable to any regulatory threshold or  air quality standards.  It is also important to note that other than an emissions inventory,  a HAPs assessment prepared  for the FAA  must not include any other type of  analysis including, but not limited atmospheric dispersion modeling, toxicity weighting, or human health risk analyses. These types  of assessments require a  more complete understanding of the  reactions of HAPs in the  atmosphere and downstream plume evolution as well as human exposure patterns.  Because the  science of these  relationships with respect to  aviation-related HAPs is still evolving, the  corresponding level of understanding is also currently limited.  As stated previously, in cases where it is necessary to prepare such an  aviation-related HAP  inventory, the inventory must be prepared following the  Speciated Organic Gas Emissions from  Airports Guidance  and using EDMS/AEDT. In this application, EDMS/AEDT applies speciation  factors to quantify individual HAP compounds. These factors estimate the quantities individual HAPs based on the total emissions of VOCs. Notably, t he EPA MOVES emission  factor model should be used to develop individual HAP speciation data for motor vehicles.  Presently, EDMS/AEDT calculates emissions for 394 different OGs. Of these, 45 are classified  as HAPs by the EPA while the  other 349 are considered to be non- toxic compounds. These 45  HAPs are listed in  Table 6-4  ( Potential HAPs to be Included in an Airport Emissions Inventory ).  Source: FAA, Guidance for Quantifying Speciated  Organic Gas Emissions from Airport Sources, September 2, 2009,  http://www.faa.gov/regulations_policies/policy_guidance/envir_policy/media/Guidance%20for%20Quantifying%20Speciated  %20Organic%20Gas%20Emissions%20from%20Airport%20Sources.pdf.  Table 6-4. Potential HAPs to be Included in an Airport Emissions Inventory  Hazardous Air Pollutants  1,1,1-Trichloroethane  Cyclohexane  Methyl alcohol  Phenol (carbolic acid)  1,3-Butadiene  Dichloromethane  Methyl chloride  Phthalic anhydride  2,2,4 Trimethylpentane  Thyl acetate  Methyl ethyl ketone  Propionaldehyde  2-Methylnaphthalene  Ethyl ether  Methyl tert butyl ether  Styrene  Acetaldehyde  Ethylbenzene  m-xylene  Toluene  Acetone  Ethylene bromide  Naphthalene  Trichloroethylene  Acrolein (2-propenal)  Ethylene glycol  n-Butyl alcohol  Trichlorotrifluoroethan  Benzaldehyde  Formaldehyde  n-Heptane  Vinyl acetate  Benzene  Isomers of xylene  n-Hexane  Butyl cellosolve  Isopropylbenzene  o-Xylene  Chlorobenzene  m & p-Xylene  Perchloroethylene  47$_{ }$