# Engineering Controls Database

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## Recreational Boats: Carbon Monoxide Exposure – Propulsion Engines Emission Controls (Catalytic Convertors)

| Problem:                                        | Epidemiologic studies have found that from 1990 to 2004, there have been approximately 540 carbon monoxide (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) [DOI 2004].There are approximately 17 million recreational boats used in the United States.  Based upon the results of studies by the National Institute for Occupational Safety and Health (NIOSH), approximately 90% of evaluated recreational boats produced potentially hazardous CO concentrations.  When boats were tested during stationary conditions, the CO concentrations were high at the stern (500 to 1,000 ppm). In addition, cabin cruiser measurements ranged from 800 to 1,000 ppm on the lower deck.There are a variety of towed water sport activities in which CO exposures may occur.  CO exposures are related to the distance behind the boat, height from the water, and operating speed. The most common of these sports are tubing, teak surfing, water skiing, wakeboarding, wake surfing, and knee boarding.                                                                                                                                                                                                                                                                                                                                    |
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| What this means to you:                         | CO is a lethal poison that is produced when fuels such as gasoline or propane are burned. It is one of many chemicals found in engine exhaust resulting from incomplete combustion. Because CO is a colorless, odorless, and tasteless gas, it can overcome an exposed person without warning. The initial symptoms of CO poisoning may include headache, dizziness, drowsiness, or nausea.  Symptoms may advance to vomiting, loss of consciousness, and collapse if prolonged or high exposures are encountered.  If the exposure level is high, loss of consciousness may occur without other symptoms.  Coma or death may occur if high exposures continue [NIOSH 1979].  The NIOSH Recommended Exposure Limit (REL) for CO is 35 ppm for full shift TWA exposure, with a ceiling limit of 200 ppm which should never be exceeded [CDC 1988].  The NIOSH REL is designed to protect workers for an 8-hour workday.  NIOSH has also established an Immediately Dangerous to Life and Health (IDLH) value for CO of 1,200 ppm [NIOSH 2000].                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| Description of control:                         | In 2006, NIOSH evaluated a catalytic control device manufactured by Indmar Marine Engines.  The evaluated ski boat was propelled by a gasoline-powered engine and could be configured with and without the catalytic converter on the exhaust manifold depending on the evaluation.  The switching of exhaust manifolds was performed to compare emissions from an uncontrolled engine to an engine with the Indmar catalytic exhaust system. The engine was tuned to manufacturer’s specifications. The exhaust systems were water jacketed to keep temperatures of the exhaust manifolds below 200 °F.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| Engineering and Physical Hazard Report Numbers: | 289-12A;                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| References:                                     | CDC (1988). MMWR 37, supp (S-7)  NIOSH Recommendations  for Occupational Safety and Health Standards. Atlanta, GA, Dept. of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health.DOI (2004). Department of the Interior (2004, October). Boat-related carbon monoxide (CO)poisonings. Retrieved January 19, 2004, from http://safetynet.smis.doi.gov/thelistbystate10-19-04.pdfMann, L.W. (2004). Carbon Monoxide Exposure While Operating an Inboard Boat and Related Water Sports Activities.  http://www.FreshAirExhaust.com.McCammon JB, Radtke T, et al. (2001). Letter of February 20, 2001 from J. McCammon, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Public Health Service, U.S. Department of Health and Human Services, T. Radke, U.S. Department of the Interior, and Dr. Robert Baron Prehospital Medical Care, Glen Canyon National Recreation Area, to Joe Alston, Park Superintendent, Glen Canyon National Recreation Area, Page, Arizona. Denver, CO, NIOSH.NIOSH (1979). A Guide to Work Relatedness of Disease. Cincinnati, OH, Dept. of Health Education and Welfare, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health.NIOSH (2000). Pocket Guide to Chemical Hazards and Other Databases:  Immediately Dangerous to Life and Health Concentrations, DHHS (NIOSH). |
| NAICS Codes:                                    | 336612                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
| Keywords:                                       | carbon monoxidecarbon monoxidecatalytic convertorscatalytic convertorscontrol technologycontrol technologyrecreational boatsrecreational boatsski boatsski boats                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| How well does this control work?                | The Indmar system significantly reduced CO exposures to boat occupants during the evaluation. For most conditions, a reduction above 90% was observed when compared to a standard exhaust system.  When comparing measurements collected directly in the exhaust opening, at idle, the Indmar technology showed reductions on the order of 93% vs. the standard technology.  The NIOSH study also noted that in order to ensure that the systems operate effectively, boat owners and operators should ensure that they follow all manufacturers’ recommendations with regard to routine maintenance and replacement schedules.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |

November 16, 2018
National Institute for Occupational Safety and Health