An evaluation of an emission control device, exhaust stack, and interlock to prevent carbon monoxide poisonings of individuals on houseboats at Callville Bay Marina, Boulder City, Nevada, report no. CT-171-27a.
Researchers from the National Institute for Occupational Safety and Health (NIOSH) conducted an evaluation of several engineering control devices that were retrofitted onto gasoline-powered, generators on houseboats to reduce the hazard of carbon monoxide poisonings from the exhaust. This evaluation was part of a series of studies conducted by NIOSH investigators during the past year to document hazardous carbon monoxide concentrations on houseboats and evaluate and recommend appropriate engineering controls to reduce the carbon monoxide hazard and eliminate carbon monoxide poisonings. The evaluated engineering controls consisted of a recently developed emissions control device (ECD), an interlock, and an exhaust stack that extended 9 feet above the upper deck of the houseboat. Results provided in this report address the performance of the ECD, the interlock system, and the ECD with the exhaust stack used in series on a single houseboat. Additional data and details concerning the performance of the exhaust stack alone are provided in a separate report. When compared to the generator having no engineering controls exhausting under the rear swim deck, results of the current evaluation indicated that use of these control systems provide a safer environment to individuals on or near the houseboat. Data gathered while the ECD was operating indicated that mean and peak carbon monoxide concentrations were reduced by two to three orders of magnitude at numerous locations on the houseboat. Average carbon monoxide concentrations near the rear swim deck of the houseboat, an area where occupants frequently congregate, were reduced from an average of 395ppm to less than 1ppm, a reduction greater than 99%. Carbon monoxide concentrations were also greatly reduced on the upper deck of the houseboat. A five gas emissions analyzer indicated that mean carbon monoixde concentrations in the generator exhaust were reduced by several orders of magnitude (from 4,534ppm to approximately 13ppm). The evaluated interlock was capable of shutting down the generator when the swim ladder was placed into the water, and the hazardous carbon monoxide concentrations near the lower rear deck dissipated within two or three minutes. Based upon the results of this study, NIOSH investigators recommend that all U.S. houseboats using gasoline-powered generators, should be retrofitted with engineering controls to reduce the hazard of carbon monoxide poisoning and death to individuals on or near the houseboat. The performance of the evaluated ECD was excellent; however, some additional testing and evaluation of this device is warranted. The interlocking system performed as designed and could help to reduce some carbon monoxide poisonings; but, this system has significant limitations that prevent it from being used as a primary control.