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Air Emissions Factors and Quantification

AP 42 Section 4.4 Polyester Resin Plastic Products Fabrication - Related Information

May 1, 2008  Table 4.4-2 Emission Factors For Uncontrolled Polyester Resin Product Fabrication Processes was updated with the following footnote:
"Users found that use of emissions factors for open molding processes from reference 9 generally underestimated emissions. As an alternative to estimating open molding emissions using reference 9 (G. A. LaFlam, Emission Factor Documentation For AP-42 Section 4.12: Polyester Resin Plastics Product Fabrication (PDF) (27 pp, 2 MB), Pacific Environmental Services, Inc., Durham, NC, November 1987), one may choose to use the emissions factors contained in the ANSI/ACMA/ICPA UEF-1-2004 Estimating Emission Factors from Open Molding Composite Processes ("UEF") document. Users who choose to use this document should employ the version that is current at the time of use. The UEF factor equations and all available supporting documentation regarding the development and validation of the UEF are available at  Exit  The official ANSI standard is also available at"  Exit

October 9, 2007  Table 4.4-2 Emission Factors For Uncontrolled Polyester Resin Product Fabrication Processes, was updated to include source classification codes (SCCs) in order to more closely identify processes with the emissions factor ranges. These codes were added so that the factor ranges could be added to WebFIRE, the EPA's on line repository for emissions factors. No new data was reviewed for the section.

February 16, 2007  Section 4.4 of AP 42 was removed from this web site as of March 18, 1998, because the emissions factors presented in that section for open molding (hand layup, spray layup) appeared to under predict styrene emissions. At that time, we had no data indicating the emission factors for other reinforced plastic composites resin application methods were in error. A number of individual site tests and studies on open molding confirmed our concerns about the open molding emissions factors. However, no new information has come to our attention that indicates the original emission factors for polymer casting (marble casting), pultrusion, continuous lamination, filament winding, and closed molding should be changed. For this reason we are returning section 4.4 to the website with these emissions factors.

We have removed table 4.4-3, typical resin monomer contents, from this section because there should never be a situation where a facility is using a resin where they do not have a material safety data sheet (MSDS) that will show the resin or gel coat monomer content. Using actual resin monomer contents is always more accurate then using an assumed number.

We have not provided revised emission factors for open molding. Emissions from these types of operations are a function of resin application method and resin monomer content, and can vary significantly. In addition, the emission factors for certain open molding resin application methods may be revised in the near future. Instead we are referring the reader to information resources that may be used to estimated emission from these operations. (See Table 4.4-2, Emission Factors For Uncontrolled Polyester Resin Product Fabrication Processes.)