Measurement of the epoxy content of paint spray aerosol: three case studies.
Herrick-RF; Ellenbecker-MJ; Smith-TJ
Appl Ind Hyg 1988 Apr; 3(4):123-128
Measurements were made of the epoxy content of aerosols generated in three commercial epoxy coating operations using a sampling and analytical procedure developed to collect these aerosols and preserve their epoxy content. The three operations involved in the study were: the spray application of an epoxy polyamide primer at an aircraft production facility in a finishing area containing four water wash spray booths (Case 1); the use of an epoxy surface coating containing coal tar pitch to protect surfaces in the corrosive environment inside a storage tank (Case 2); and the application of an epoxy resin to the ceiling of an industrial building (Case 3). All three coating systems employed epoxy resins based on a diglycidyl-ether of bisphenol-A (1675543) (DGBA). Aerosol samples were collected throughout the duration of the painting process at locations where painters worked during the operation. Aerosol epoxide contents were determined by the reaction of the epoxide functional groups with a known excess quantity of bromide and by measurement of the residual bromide in the reaction mixture. In Case 1 the aerosol mass concentrations were generally below 2 milligrams per cubic meter (mg/m3), and epoxide contents of the aerosol collected at all locations were below the limit of detection. In Case 2 the aerosol mass concentrations ranged from 1.96 to 4.49mg/m3, and the aerosol epoxide contents ranged from 2.11 to 6.91 microequivalents per cubic meter (microeq/m3). In Case 3 the aerosol mass concentrations ranged from 11.0 to 24.7mg/m3, and the aerosol epoxide contents ranged from 2.86 to 11.7microeq/m3. Even though the three locations studied all used systems based on a DGBA type resin, a wide range of aerosol concentrations was observed. The method of application was the most significant difference between the three locations studied. The compressed air system used in Case 1 generated a smaller aerosol than the other systems resulting in more rapid drying. The authors state that the rate of the epoxy curing reactions and the resulting aerosol epoxide content appear to be strongly related to particle size and that nonvolatile aerosol mass is not a good predictor of aerosol epoxide concentration. The authors conclude that the epoxide content of aerosols should be measured when assessments of occupational exposures of painters using spray techniques are being conducted.
NIOSH-Author; Workplace-studies; Paint-spraying; Epoxides; Exposure-levels; Environmental-exposure; Occupational-hazards; Paints; Protective-coatings; Quantitative-analysis; Aerosol-particles
Applied Industrial Hygiene