Some portable pressure washers can be life-threatening when used improperly, according to George Maher, North Dakota State University Extension Service agriculture safety specialist. "A small gasoline engine, when used as the power source, produces carbon monoxide in sufficient quantities to kill," Maher says.

Every year, operators of portable power washers fall victim to the carbon monoxide produced by these machines. Indoor use, where doors and windows are closed, can easily lead to fatality.

To prevent a similar fate, Maher offers the following tips:

Always follow the manufacturers directions (which will always insist upon adequate ventilation). Every internal combustion engine produces deadly carbon monoxide. Any building that is tight and warm enough to allow the use of a pressure washer is tight enough to allow asphyxiation to occur. It is never safe to run a small gasoline engine in a closed building; ventilation is an absolute must.

Never depend on the early symptoms of carbon monoxide poisoning to warn you to evacuate the building. It can't be determined when a person is going to collapse and be unable to get to fresh air. It is possible that you won't be able to prevent a death from occurring even if you get to fresh air.

Select an electrically powered pressure cleaner, if there is a strong enough need to operate this type of equipment in a closed building of room. Be sure it is electrically grounded to prevent electrocution. "There is risk in using any powered machine."

Maher says. "Always select the machine with the lowest risk and even then follow the instructions and be careful."