March 18, 1998 The USEPA's Emission Factors and Inventory Group (EFIG) is making available today for review, comment, and use an emissions characterization report entitled "CFA Emission Models for the Reinforced Plastics Industries", dated February 28, 1998 and prepared by Dr. Robert Haberlein of Engineering Environmental on behalf of the Composite Fabricators Association (CFA), the International Cast Polymer Association, and the Composites Institute. The report describes the development of a set of four emission estimating equations or models that can be used to predict the styrene emissions from open molding processes used by the reinforced plastics industry. This material is related to existing AP-42 section 4.4, "Polyester Resin Plastic Products Fabrication". It is also related to a report prepared by the National Marine Manufacturers Association (NMMA) entitled "Baseline Characterization of Emissions from Fiberglass Boat Manufacturing", which was posted on USEPA's CHIEF web site (www.epa.gov/ttn/chief/ap42etc.html) on January 6, 1998. The CFA and NMMA testing results and reports are generally consistent, and they support the suspicion that the existing AP-42 section may underpredict styrene emissions from most polyester resin operations. For these reasons we are removing the existing AP-42 section from the CHIEF web site today and requesting comments on the two reports while we begin drafting a replacement AP-42 section which will be based largely on the two reports. Meanwhile, the USEPA's Office of Research and Development (ORD) and Research Triangle Institute (RTI) are continuing their efforts to bring all of the available data together into a consistent, explanatory model, and we hope to post those results on the CHIEF web site when they become available. The CFA is also planning additional testing to quantify the effects of combining various control techniques. Although the CFA report presents both multi-variable and single variable equations for predicting emissions from each of four open molding processes, EFIG agrees with the report's conclusion that the single-variable (% styrene in the resin) equations account for almost all of the variation due to parameters that can be reasonably monitored in a production setting. The recommended one-variable equations and associated control factors are summarized as eqns. 12, 15, 18, and 21 on pages 20 and 21 of the report. Table 2.16 on page 24 of the report provides a table of results from these equations for a number of given input assumptions. The equations have also been packaged into a spreadsheet model to facilitate users generating emission factors for their own scenarios. The spreadsheet model is available from this web site in three formats: QuattroPro, Excel, and Lotus. Users should note that the equations in the CFA report and the spreadsheet models produce emission factors in units of "% neat resin". These factors are expressed as decimals and should be multiplied directly by the pounds of neat resin consumed to yield pounds of styrene emissions. There is no need to divide by 100. Also note that these units differ from the old AP-42 units and the NMMA report units, which are "% of available styrene". Users should be aware that although the NMMA, CFA, and RTI work has made great advances in quantifying the effects of many different parameters on emissions, the impacts of one of the most significant parameters, the degree of overspray, remains difficult to quantify in a simple manner. The percentage of styrene in the resin which escapes to the atmosphere appears to be much greater for the resin which is sprayed off the edge of the mold as compared to the resin which lands on the mold. Thus, facilities which have a larger proportion of oversprayed material than the operations tested can expect to have higher percentages of the styrene emitted. The USEPA thanks the CFA, their members, Dr. Haberlein, Larry Craigie of Dow Chemical, RTI, and others who contributed to the development and analysis of the data presented in this report. Comments on this material can be addressed to: Ron Ryan U.S. EPA (MD-14) RTP, NC 27711 Phone - (919) 541-4330 FAX - (919) 541-0684 EMAIL - ryan.ron@epamail.epa.gov