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Evaluation of the Sideswipe exhaust system to reduce carbon monoxide exposure during motor boating and wake surfing, Yosemite Lake, Merced, California.

Marlow DA; Hammond D; Earnest GS
Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, EPHB 171-37a, 2005 Dec; :1-63
Under an interagency agreement with the United States Coast Guard, National Institute for Occupational Safety and Health (NIOSH) researchers evaluated carbon monoxide (CO) emissions and exposures from two 2005 Centurion Avalanche ski boats equipped with carbureted inboard engines. One of the boats evaluated was equipped with the Sideswipe exhaust system, while the other was equipped with transom stern exhaust. In the Sideswipe exhaust system the engine exhaust is discharged from the sides of the boat instead of the stern. This investigation builds upon a series of recent studies to reduce CO exposures and poisonings on houseboats and other recreational boats. Epidemiologic studies have found that from 1990 to 2004, there have been approximately 540 CO poisonings associated with exhaust from gasoline powered marine engines on recreational boats. Two hundred and twenty-five of the poisonings occurred on non-houseboats (other types of recreational boats). This study was performed for the U.S. Coast Guard for three purposes: to serve as an independent evaluation of the Sideswipe exhaust system, to gather additional data building upon previous studies related to CO concentrations and exposures near ski boats operating under various conditions, and to collect personal exposure data on an individual performing wake surfing. Ski boats, one with Sideswipe exhaust and one with stern exhaust, were evaluated both while stationary and while moving at multiple speeds ranging from 2.5 to 20 miles per hour (mph). CO concentrations were measured by multiple real-time instruments, placed at different locations on the boats and at various distances (10 to 60 feet) behind the boat in motion. Study results indicated that CO concentrations on the boat were generally highest while the boat was stationary. CO concentrations were lower when the boat was underway and decreased as boat speed and distance from the boat increased. CO concentrations were highest near the water surface and decreased as height above the water increased. The Sideswipe exhaust system significantly reduced CO concentrations (by 60- 90%) on and behind the boat when operating at speeds of 10 mph or greater. When the boat was stationary or operating at speeds below 10 mph (i.e. slow no-wake speeds), CO reductions were mixed. Average personal CO exposures to a wake surfer (located approximately ten feet behind the boat and slightly off center) were approximately 17 parts per million (ppm) and the Sideswipe system was able to reduce exposures to approximately 3 ppm. CO concentrations measured 10 to 60 feet behind the boat were relatively low with or without the Sideswipe system. One particular area of concern relates to towed water sports activities where people could be near the boat, operating at slow speeds, and near the water (such as some tubing activities). The Sideswipe system may be beneficial in helping to reduce CO exposures to individuals involved in a variety of towed water sports activities. Further research is warranted to provide a better understanding of the CO reduction mechanisms.
Region-9; Boat-manufacturing-industry; Emission-sources; Equipment-design; Exhaust-gases; Exhaust-systems; Combustion-engines; Combustion-gases; Control-technology; Exposure-assessment; Poison-gases
National Institute for Occupational Safety and Health, Division of Applied Research and Technology, 4676 Columbia Parkway, MS - R5, Cincinnati, OH 45226
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Field Studies; Control Technology
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Interagency Agreement
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NIOSH Division
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National Institute for Occupational Safety and Health
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division