A recommended approach to recirculation of industrial exhaust is evaluated. Field surveys conducted in four facilities with partially or completely constructed recirculating exhaust air systems to determine the usefulness and applicability of the recommended approach developed by NIOSH are discussed. Case studies are presented for a lead (7439921) battery assembly operation, a woodworking operation, a wet grinding process for manganese (7439965) steel, and an enamel blending process. The process, sampling methods, and results are presented for each case, followed by a detailed section on the applicability of the survey findings to the recommended approach. Recommendations are given for improvements in the feasibility assessment and modeling approach and for future research. The authors conclude that the recommended approach provides a useful method for examining the feasibility of recirculating exhaust air in industrial operations. Development of a practical field manual to bring together information on the design, construction, operation, maintenance and testing of recirculation systems is recommended, and a format for such a manual is proposed.
U.S. Department of H.E.W., NIOSH, Cincinnati, Ohio, 188 pages