Effective Local Exhaust Ventilation for Controlling Formaldehyde Exposures during Embalming

Abstract

Abstract Previous studies have found that formaldehyde exposures to embalmers during the embalming process exceeded current occupational health criteria and standards. There are currently just over 20,000 mortuaries in the United States, employing 75,000 people. Mortuaries, as small businesses, typically do not have access to the occupational health and safety expertise that larger companies do. Therefore, a research study was conducted to develop and evaluate a local exhaust ventilation system to control formaldehyde exposures. The control design that was developed consisted of a pair of 6-ft-long slot hoods placed on each side of the embalming table. Through a series of laboratory tests, an optimum flow rate (20 m3/min) was determined for the local exhaust ventilation system. The final design was field tested at a college of mortuary science to determine its effectiveness. A series of 16 tests were conducted with a variety of different embalming procedures. For each test, two personal and three area samples were collected. The results from these tests showed that the local exhaust ventilation system controlled the mean personal formaldehyde concentrations during the embalming procedures to 0.73 ppm or less (95 percent confidence). Area samples in the isolation room indicated mean formaldehyde concentrations of 0.31 ppm or less (95 percent confidence). Formaldehyde samples also were collected from the exhaust duct of the local exhaust ventilation system. From these samples, an average emission factor for the 16 tests was estimated. Using this factor, dilution ventilation exhaust requirements were determined. This calculation indicated that from 4 to 13 times more air, depending upon mixing in the room, would need to be exhausted by a dilution ventilation system to achieve the same control as the local exhaust ventilation system. Because every cubic foot of air exhausted from the room must be replaced with outside air, make-up air costs (heating or cooling) would be considerably less for the local exhaust ventilation system than for a dilution ventilation system. The tests reported here indicate that a system based upon a slot hood design would be effective in controlling an embalmer's exposure to formaldehyde. Additionally, when compared to dilution ventilation, the local exhaust ventilation system is a more cost effective means for achieving control of formaldehyde emissions during the embalming process. Gressel, M.G.; Hughes, R.T.: Effective Local Exhaust Ventilation for Controlling Formaldehyde Exposures during Embalming. Appl. Occup. Environ. Hyg. 7(12):840–845; 1992.