NIOSH Warns of Deadly Carbon Monoxide Hazard from Using Pressure Washers Indoors

NIOSH Update:

Monday, May 10, 1993
Contact: Fred Blosser (NIOSH) (202) 260-8519

According to the National Institute for Occupational safety and Health(NIOSH), Americans who use gasoline-powered pressure washers indoors arerisking their lives. A 35-year-old farmer recently died from carbon monoxidepoisoning while using one of these washers in an enclosed barn. NIOSH warnsall workers not to use these machines indoors–it can be a deadly mistake.”We must act before this silent killer’ strikes again. Workers mustbe aware of the hazard and prevent exposure to this potentially fatal gas.Carbon monoxide strikes quickly, and it strikes without warning,” stressedNIOSH director, Dr. J. Donald Millar. The gas is colorless, odorless, tasteless,and gives no signs of its presence. “It is critical that workers know whencarbon monoxide can be a danger and how they can be protected,” said Millar.

All gasoline-powered engines produce carbon monoxide. This gas can rapidlybuild up in any indoor area, and individuals can be overcome without evenrealizing they are being exposed. Confusion, headache, dizziness, fatigue,and weakness may set in too quickly for victims to save themselves. Eachof the victims interviewed by NIOSH expressed shock at how quickly theywere overcome. A farm woman recently poisoned in Iowa stressed, “I was amazed at how it affected my ability to think clearly and to get out.” Carbon monoxide poisoning can cause permanent brain damage, including changes in personality and memory. Once inhaled, carbon monoxide decreased the ability of the blood to carry oxygen to the brain and other vital organs. Even low levels of carbon monoxide can set off chest pains and heart attacks in people with coronary artery disease.

This document describes five incidents in which farmers were overcomewhile using gasoline-powered pressure washers to clean buildings used tohouse animals. While we do not know how many farmers are using this hazardousprocedure, we do know that the number of Americans using this type of washeris rising. According to Vernon Meyer, Swine housing Specialist, Iowa StateUniversity, “Two-thirds of swine producers now use pressure washers forcleaning, and that number is expected to go up.” As the market for thesedevices in agriculture and other industries continues to increase, it isessential that users be informed of the carbon monoxide hazard. We mustinsure that fatalities do not increase with the market.

In each of the injuries identified, the farmer had brought the machine into a building. Though the machines themselves should be placed outside and the hoses brought inside, farmers sometimes place the equipment insidethe building because the hose is not long enough to reach all the areabeing cleaned or because of concern about water in the machine freezingduring cold weather. The following page describes the fatal and near fatalincidents and the methods of preventing future injury and death from thishazard. Though all of these incidents occurred on farms, any indoor useof gasoline powered equipment could be disabling or fatal.

Preventable Poisonings

The National Institute of Occupational Safety and Health (NIOSH) has receivedreports of one fatality and four nonfatal cases of carbon monoxide poisoning from the indoor use of gasoline powered pressure washers in the state ofIowa. Each of the victims was using the washer to clean buildings usedto house farm animals.On January 15, 1993, a 35-year-old man was found several hours after dyinginside the building he had been cleaning. The victim was using a newlypurchased pressure washer with an 11 horsepower engine. He worked alonewith closed doors and windows for about one-half hour before being overcome. The medical examiner reported a very high level of carboxyhemoglobin (anindicator of carbon monoxide poisoning) in his blood. After his death, his family sold the farm.

On December 30, 1992, a 12-year-old boy was found in a coma. He had placedan 11 horsepower gasoline-powered pressure washer in the outside doorwayof a building he was cleaning and worked for less than one half-hour beforebeing overcome. Blood tests indicated he had inhaled a great deal of carbonmonoxide. Due to the seriousness of his condition, he was taken to a traumaunit where he was given intensive oxygen treatment. He was released formthe hospital seven days later.

On November 3, 1992, a 35-year-old woman came home fatigued, dizzy andconfused after working with a 4 horsepower gasoline-powered pressure washer.She had worked on and off for about seven hours with the machine insidea building with a low ceiling, three open doors, and running exhaust fans.Her family brought her to a local emergency room. Blood testes confirmedshe had been poisoned by carbon monoxide. She was treated with oxygen andreleased.

On April 18, 1992, a 32-year-old woman was found confused and complainingof a severe headache and dizziness. She had been working alone off andon for six and a half hours in a building with exhaust fans running. Shewas using a 13 horsepower gasoline powered pressure washer with an openoutside door. Here husband took her to a local emergency room, where shewas diagnosed with carbon monoxide poisoning, treated with oxygen, andreleased.

On January 2, 1992, a 37-year-old man operated a 9 horsepower washer inan unventilated room for about 30 minutes. When he attempted to refuelthe washer, he became weak, dizzy, and confused. He crawled to his houseand was taken to a hospital. He was treated with oxygen for carbon monoxidepoisoning and released.

Steps for Prevention

While electrically powered pressure washers are available, NIOSH has not evaluated the safety of these devices. If you are using gasoline powered equipment, take the following precautions:

Do not operate machinery with gasoline engines inside any building.

Though warning notices in operating manuals advise that the equipment is not to be used without adequate ventilation, it can be difficult to determine how much ventilation is adequate. One Episode described in thisreport occurred with three doors open and exhaust fans on.

Remember that even small engines can produce deadly levels of carbon monoxide.

NIOSH will continue to investigate the problem of using gasoline-poweredpressure washers in farm buildings and will address ventilation, warninglabels, and freezing problems in an upcoming report.

For information about this or other occupational safety and health concerns,call toll free: 1-800-35-NIOSH.

DHHS (NIOSH) Publication No. 93-117

Page last reviewed: July 22, 2015