Evaluation of Styrene Emissions from a Shower Stall/Bathtub Manufacturing Facility

Current EPA emission factors (AP42) for styrene emissions from the production of polyester-resin-reinforced plastic products represent a composite of spraying and post-spraying emissions (from curing molds) from shower stall/bathtub manufacturing plants that use compressed-air-powered spray guns to apply catalyzed styrene resins to prepared molds. Because each step of manufacture (gel coating, first-stage spray lay-up, and second-stage spray lay-up) creates large surface areas from which volatile styrene monomer can evaporate, non-spraying emissions can constitute a large fraction of the styrene emitted to the atmosphere. Thus, it is of interest to quantify the level of non-spraying styrene emissions characteristic of this industry to validate current emission factors for spraying, as well as to develop emission factors for emissions not directly related to a spraying activity. In this study, emissions were measured at a representative facility (Eljer Plumbingware in Wilson, NC) that manufactures polyester-resin-reinforced shower stalls and bathtubs by spraying styrene-based resins onto molds in vented, open, spray booths. Styrene emissions were characterized for the three stages of manufacture by measuring styrene concentrations at the vents of spray booths used in each part of the process. In addition, styrene concentrations were measured at each ventilation fan exhaust. Emission levels were determined using EPA Method 18 to obtain integrated emissions samples and total hydrocarbon analyzers to measure continuous emissions levels during the EPA Method 18 sampling. Analysis of the EPA Reference Method data indicates that: (1) styrene monomer is the only volatile organic compound released in this process; (2) overall, approximately 4% of all material sprayed is lost to atmospheric emissions as styrene (approximately 19% of styrene sprayed); and (3) emissions vary for each phase of manufacture, with post-spraying emissions of styrene (from curing molds) constituting a large part, approximately 29%, of all emissions. This Project Summary was developed by EPA's National Risk Management Research Laboratory's Air Pollution Prevention and Control Division, Research Triangle Park, NC, to announce key findings of the research project that is fully documented in a separate report of the same title (see Project Report ordering information at back).