NIOSH warns against the use of gasoline powered pressure washers indoors because of the potential for carbon-monoxide (630080) poisoning. As carbon-monoxide is colorless, odorless, tasteless, and gives no signs of its presence, it is important that the hazards be recognized where carbon-monoxide can be generated. All gasoline powered engines produce the gas. It can build up rapidly in any indoor area. Individuals can be overcome without even realizing that they are being exposed. Five incidents were cited where farmers were overcome while using gasoline powered pressure washers to clean buildings used to house animals. The victims included a 35 year old man working alone with closed doors and windows for about one half hour; a 12 year old boy who had placed the washer in the outside doorway of a building he was cleaning and worked for less than one half hour; a 35 year old woman fatigued, dizzy and confused after working with a washer for about 7 hours on and off; a 32 year old woman who had been using the equipment for 6.5 hours; and a 37 year old man who used the equipment in an unventilated room for about 30 minutes. One of these victims died. Some had taken the precaution of placing the motor outside the area they were cleaning, using exhaust fans, and opening doors. To prevent similar occurrences, never operate machinery with gasoline engines inside any building. Even small gasoline powered engines may produce deadly levels of carbon-monoxide.