NIOSH logo and tagline

Safeguards Against Carbon Monoxide Risk from Small Gasoline Engines Recommended by NIOSH, Partners

NIOSH Update:

Contact: Fred Blosser (202) 260-8519
January 27, 1997

Employers, workers, and others should take precautions to prevent carbon monoxide poisoning from small gasoline-powered equipment in enclosed spaces.

Using small gasoline-powered engines and tools indoors or in partially enclosed areas can put operators at risk of serious illness and death from carbon monoxide poisoning, even in apparently well ventilated spaces, the National Institute for Occupational Safety and Health (NIOSH) and four other agencies cautioned.

Employers, workers, consumers, and others should be aware of the hazard and take precautionary steps, the agencies recommended in a joint alert document. The alert pertains to indoor or enclosed use of equipment such as high-pressure washers, concrete cutting saws, power trowels, floor buffers, welders, pumps, compressors, and generators.

The joint alert was developed by NIOSH, the Occupational Safety and Health Administration, the U.S. Consumer Product Safety Commission, the U.S. Environmental Protection Agency, and the Colorado Department of Public Health and Environment. NIOSH is part of the Centers for Disease Control and Prevention in the U.S. Department of Health and Human Services.

“Partnerships are essential for developing and disseminating practical information that will benefit as many people as possible,” said NIOSH Director Linda Rosenstock, M.D., M.P.H. “The new alert combines a wide range of expertise to highlight the serious risk of carbon monoxide poisoning and suggest effective preventive measures.”

The agencies are distributing the alert widely to industry, labor groups, consumer organizations, and others. Written in non-technical language, the alert makes specific recommendations for equipment users, employers, tool rental agencies, and tool manufacturers. It also includes a short summary for easy posting.

Studies show that the risk of using small gasoline-powered engines in enclosed or partially enclosed areas is not widely recognized, the joint alert said. Even when the hazard is perceived, operators and others often believe mistakenly that they can avoid risk by opening doors and windows or by running exhaust fans.

The joint alert warns that carbon monoxide is particularly hazardous because it can accumulate rapidly in enclosed or semi-enclosed spaces and can overcome victims without warning. Deaths and serious illnesses from small engine exhaust have occurred among parking garage employees, plumbers, flooring installers, farmers, drywall finishers, and other workers.

The following examples show a range of effects caused by CO poisoning in a variety of work settings.

A farm owner died of CO poisoning while using an 11-horsepower gasoline-powered pressure washer to clean his barn. He had worked about 20 minutes before being overcome.

A municipal employee at an indoor water treatment plant lost consciousness while trying to exit a 59,000 cubic foot room where he had been working with an 8-horsepower, gasoline-powered pump. Doors adjacent to the work area were open while he worked. His hospital diagnosis was CO poisoning.

Five workers were treated for CO poisoning after using two 8-horsepower gasoline-powered pressure washers in a poorly ventilated underground parking garage.

A plumber used a gasoline-powered concrete saw in a basement with open doors and windows, and a cooling fan. He experienced a severe headache and dizziness, and began to act in a paranoid manner. His symptoms were related to CO poisoning.

The following precautions should be taken to prevent carbon monoxide poisoning from small gasoline-powered engines and tools.

  • Do not operate gasoline-powered small devices or tools indoors unless the engine unit can be located outside and away from ventilation air intakes.
  • Consider substituting other types of equipment for gasoline-powered small engines or tools, such as tools powered by electricity or compressed air, if they are available and can be used safely
  • Recognize potential sources and symptoms of carbon monoxide (CO) poisoning.
  • Design and label equipment for safe operation.
  • Provide and use personal monitors with audible alarms for timely warning of high CO concentrations.

Copies of the alert, “Preventing Carbon Monoxide Poisoning from Small Gasoline-Powered Engines and Tools,” DHHS (NIOSH) Publication No. 96-118, are available from