Reducing employee exposure potential using the ANSI/ASHRAE 110 Method of Testing Performance of Laboratory Fume Hoods as a diagnostic tool.

The primary goal of a laboratory ventilation system is to assure that employee exposure to hazardous chemicals does not exceed acceptable levels. Industrial hygienists at Eli Lilly & Co. were concerned about the adequacy of fume hoods to protect workers in an aging laboratory facility. Wanting to conduct a comprehensive series of tests for a true reading on the containment effectiveness of these hoods, the industrial hygienists went beyond the traditional face velocity tests. Tests prescribed in the ANSI/ASHRAE 110 Method of Testing Performance of Laboratory Fume Hoods (ASHRAE 110) standard including low- and high-volume smoke tests, face velocity tests, and tracer gas containment tests indicated that many of the hoods did not meet industry consensus standards for containment (0.1 ppm), yet met industry recommended face velocity specifications (80-120 ft/min). Based on the results of performance tests and engineering observations of the facility, apparent causes of poor performance were identified, and a mitigation plan was implemented to bring the hoods to the desired containment standards. After completion of the improvements, retesting was conducted to confirm achievement of these standards. Pre- and postmitigation test results, indicating a 99.5% reduction in tracer gas leakage or potential employee exposures, build a strong case for a more complete testing protocol as specified by the ASHRAE 110 test method. The authors recommend that traditional face velocity testing alone be discontinued in favor of the ASHRAE 110 method as a quantitative measure of fume hood performance coupled with the traditional face velocity measurement at periodic intervals to assure continued performance.