Carbon monoxide emissions and exposures on recreational boats under various operating conditions: Lake Mead, Nevada and Lake Powell, Arizona, report no. CT-171-05ee2.
Under an interagency agreement with the United States Coast Guard, National Institute for Occupational Safety and Health (NIOSH) researchers evaluated carbon monoxide (CO) exposures on over ten recreational boats in the United States, including ski boats, cabin cruisers, deck boats, fishing boats, and personal watercraft. Most of the evaluated boats were speed boats or cabin cruisers, t:anging in age from new to 25 years o1d. These boats had gasoline-powered, propulsion engines, and the evaluated cabin cruisers used gasoline-powered generators to provide electricity. This investigation grew from a series of recent studies to reduce CO exposures and poisonings on houseboats. Epidemiologic investigations found that from 1990 to 2000, 111 CO poisonings occurred on Lake Powell, near the Arizona and Utah border. Seventy-four of the poisonings occurred on houseboats and 37 poisonings occurred on other types of recreational boats. NIOSH researchers are aware of 106 nationwide CO poisonings associated with recreational boats (nonhouseboats). This study was performed for the U.S. Coast Guard to better understand how CO poisonings can occur on recreational boats and to identify the most hazardous conditions. Boats were evaluated while stationary and at multiple speeds, ranging from 2.5 to 25 miles per hour. CO concentrations were measured by multiple real-time instruments, which were placed at different locations on the boats and at various distances behind the boat while moving. Study results indicated that stationary conditions were generally the most hazardous; however, many boats while moving had elevated CO concentrations near the rear deck. Most of the evaluated boats generated hazardous CO concentrations: peak CO concentrations often exceeded 1,000 parts per million (ppm), while average CO concentrations were well over 100 ppm at the stern (rear). Two boats, one with a 150-horsepower (hp), 2-stroke, direct-fuel injected Evinrude Ficht outboard engine, and the other, with a 40-hp, 4-stroke Johnson outboard engine-had dramatically lower CO concentrations than any of the other evaluated boats. Peak and average CO concentrations for these two outboard engines were an order of magnitude lower than engines on most of the other evaluated boats. These two new engines depended on recently developed technologies to burn cleanly and comply with the EP A regulations for outboard marine engInes. Greater use of gasoline-powered marine engines having engineering controls to lower CO emissions could dramatically reduce the likelihood of CO poisonings related to recreational boating. Development and use of emission control technologies such as catalytic converters and emission control devices (ECDs), and greater use of cleaner-burning drive engines and generators could minimize the future number of CO poisonings in the marine environment.