Evaluation of the "Fresh Air Exhaust (TM)" system to reduce carbon monoxide exposure during motor boating and wake surfing (Lake Austin, Texas).
Marlow DA; Guishard C; Patterson A; 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 171-35a, 2004 Aug; :1-40
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 on a 2001 Ski Nautique recreational boat equipped with a carbureted inboard engine. The boat was evaluated with and without a Fresh Air Exhaust (FAE) emission control system. The Ski Nautique's engine normally discharges the exhaust through two 4-inch openings at the stern of the boat, typically a few inches below the water line. The FAE system was retrofitted onto the exhaust discharge in order to route the separate exhausts to a single location and discharge the exhaust approximately 14-inches downward directly behind the propeller wash area. 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 US. Coast Guard for three purposes: 1) to serve as an independent evaluation of the FAE system; 2) to gather additional data building upon previous studies related to CO concentrations and exposures near ski boats operating under various conditions; and 3) to collect personal exposure data on an individual performing wake surfing. The ski boat was evaluated with and without the FAE system, both while stationary and while moving at multiple speeds ranging from 2.5 to 20 miles per hour. 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 tended to fall when the boat was underway and decreased as boat speed and distance increased. CO concentrations were highest closest to the water and fell as height above the water increased. The FAE system significantly reduced CO concentrations (by 60- 90%) on and behind the boat when operating at speeds of 10 miles per hour (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 ppm, and the FAE system was able to reduce exposures to approximately 3 ppm (an 80% reduction). The authors conclude that the CO concentrations measured 10 to 60 feet behind the boat appear to be relatively low with or without the FAE system. One particular area of concern relates to towed water sports activities were people could be near the boat, operating at slow speeds, and near the water (such as some tubing activities). The FAE system could 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.
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