Laboratory fume hood and exhaust fan penthouse exposure risk analysis using the ANSI/ASHRAE 110-1995 and other tracer gas test methods.

The use of the laboratory fume hood as the primary containment device in the laboratory has been a standard practice for almost half a century. Quantitative testing of the performance of these devices, however; is a more recent discipline. The use of the ANSI/ASHRAE 110-1995, Method of Testing Performance of Laboratory Fume Hoods (ASH RAE 1995) is becoming a standard specification in the purchase of new fume hoods, the commissioning of new laboratory facilities, and benchmarking fume hoods in existing facilities. Part I of this paper proposes a risk analysis method by which worker exposure to hazardous substances used in laboratory fume hoods may be estimated using results from the ASHRAE 110 method and formulae to extrapolate this information into potential exposure scenarios. Contaminated air leaking from hazardous exhaust systems located inside buildings or fan penthouses can pose a health risk to building occupants and maintenance workers. This is why prudent design practices for new buildings recommend that the fans powering these systems be located outside. In existing buildings with fans located inside or where a penthouse is required for weather conditions, however; it may be necessary to estimate potential worker exposure to hazardous agents released by these systems into the worker's environment. Part II of this paper proposes a method and formulae by which this risk may be evaluated based on measurement of leakage using a tracer gas release, capture, and detection method.