Experimental Evaluation of Spray Painter Worker Orientation and Spray Distance Using a Distance Guide to Reduce Airborne Exposure to Hexavalent Chromium Paints and Primers

Abstract

Hexavalent chromium-based primers and paints, which are used widely in the aerospace industry as anti-corrosive coatings, pose a health risk to painters and other workers exposed to the paints and primers. Hexavalent chromium has been established as a carcinogen associated with cancers of the lung and nasal passages. Moreover, hexavalent chromium is associated with irritant and allergic contact dermatitis and gastrointestinal disorders. Previous studies have shown evidence of airborne overexposure to painters when utilizing traditional spray paint booth ventilation. The evaluation of work practices, specifically worker orientation in the spray paint booth and maintaining the proper spraying distance, may assist with further lowering the exposure to hexavalent chromium and complying with occupational exposure limits. The objectives of this study were to evaluate the effects of worker orientation within the spray paint booth and spraying distance (distance from the spray paint nozzle to the part being coated) in reducing paint aerosol exposures as a surrogate for hexavalent chromium exposure. Four orientations with respect to the flow of air into the booth were evaluated: 0o, 45o, 90o, and 180o. Three spray distances were evaluated: 3, 6, and 12 inches. Paint aerosol concentrations were measured using a Thermo Scientific PDR 1500 real-time aerosol monitor. Results showed an association between orientation and aerosol concentrations with the geometric mean concentration increasing as orientation moved from 0o (directly upwind) to 180o (directly downwind): 0o (0.08 µg/m3/gram), 45o (0.47 µg/m3/gram), 90o (2.69 µg/m3/gram), and 180o (14.0 µg/m3/gram). Changing the spray distance did not reveal an association with aerosol exposure concentrations. Worker orientations that place the painter upwind of the target parts showed decreased paint aerosol exposures and potentially hexavalent chromium exposures. While additional research is required to establish the association between aerosol paint and hexavalent chromium exposures, this research suggests that optimizing spray painter work practices may aid in reducing hexavalent chromium exposures resulting from hexavalent chromium based paints and primers.