13 Mar Carbon Monoxide

CARBON MONOXIDE (CO)

Carbon monoxide (CO) is a colorless, odorless, tasteless, and highly toxic gas produced by incomplete combustion of carbon-containing fuels. Because it cannot be detected by sight or smell, workers may be exposed without realizing that a hazardous atmosphere exists.

Common workplace sources include gasoline-, diesel-, propane-, and other fuel-powered:

• Generators.
• Forklifts and other powered industrial equipment.
• Pressure washers.
• Air compressors.
• Heaters and furnaces.
• Pumps.
• Saws and other portable equipment.
• Vehicles and engines.

CO can accumulate rapidly in buildings, enclosed or partially enclosed spaces, confined spaces, trenches, garages, trailers, and other areas with inadequate ventilation.

How Carbon Monoxide Affects the Body

Carbon monoxide does not primarily harm workers by displacing oxygen from the surrounding air. Instead, when inhaled, CO enters the bloodstream and binds strongly to hemoglobin, reducing the blood’s ability to transport oxygen to the body’s tissues and organs.

Exposure can cause serious illness, unconsciousness, permanent injury, or death.

Signs and Symptoms of CO Exposure

Symptoms vary depending on the concentration and duration of exposure and may include:

• Headache.
• Dizziness.
• Weakness or fatigue.
• Nausea or vomiting.
• Confusion or impaired judgment.
• Visual disturbances.
• Chest discomfort.
• Drowsiness.
• Loss of coordination.
• Unconsciousness.
• Death.

CO poisoning can occur rapidly at high concentrations. Workers experiencing symptoms should immediately leave the affected area and move to fresh air, provided they can do so safely.

Occupational Exposure Limits

For Federal OSHA, the permissible exposure limit (PEL) for carbon monoxide is 50 parts per million (ppm) as an 8-hour time-weighted average (TWA).

Other occupational exposure guidelines may be more protective. For example, NIOSH recommends 35 ppm as a TWA with a 200 ppm ceiling.

Applicable company, client, state, or site-specific requirements should always be followed when they are more stringent.

Preventing Carbon Monoxide Exposure

1. Control the Source

Whenever possible, eliminate or substitute fuel-powered equipment in enclosed work areas.

• Use electric, battery-powered, or other non-combustion equipment where feasible.
• Locate generators, compressors, engines, and other exhaust-producing equipment outdoors and away from doors, windows, air intakes, hatches, and other building openings.
• Never operate gasoline-powered equipment indoors or in enclosed spaces unless specifically evaluated and controlled for CO hazards.
• Maintain engines and combustion equipment according to manufacturer requirements.

2. Provide Adequate Ventilation

Ventilation should prevent CO from accumulating in occupied areas.

Do not assume an area is safe merely because doors or windows are open. CO can reach hazardous concentrations even in areas that appear to have ventilation, particularly when combustion equipment is operating nearby.

Mechanical ventilation may be necessary depending on the equipment, work area, and atmospheric conditions.

3. Monitor the Atmosphere

Where CO exposure could reasonably occur:

• Use properly selected and calibrated direct-reading CO monitors.
• Test the atmosphere before entering potentially hazardous areas when appropriate.
• Continue monitoring when changing conditions could cause CO concentrations to increase.
• Follow established alarm levels and evacuation procedures.
• Never ignore or disable a CO monitor alarm.

Atmospheric testing is particularly important in confined and enclosed spaces where exhaust gases can accumulate rapidly.

If CO Exposure Is Suspected

If a worker experiences symptoms of possible CO poisoning or a CO monitor alarms:

1. Stop work and leave the affected area immediately, if this can be done safely.
2. Move to fresh air.
3. Warn others and prevent unauthorized entry into the affected area.
4. Notify the supervisor or appropriate emergency personnel.
5. Obtain emergency medical assistance for anyone experiencing symptoms or suspected of significant exposure.
6. Do not re-enter the area until the source has been identified and controlled and atmospheric testing confirms that conditions are safe.

Never enter a suspected high-CO atmosphere to rescue another worker without appropriate training, respiratory protection, and rescue procedures. An unprotected rescuer can quickly become another victim.

Remember

You cannot see, smell, or taste carbon monoxide. Never rely on your senses to determine whether an area is safe. Control combustion sources, provide adequate ventilation, monitor potentially hazardous atmospheres, and recognize the early symptoms of exposure.

Key Safety Points

• CO is a colorless, odorless, and highly toxic gas.
• Fuel-burning engines and equipment are common workplace sources.
• CO prevents the blood from effectively carrying oxygen.
• Hazardous concentrations can develop rapidly in enclosed or partially enclosed areas.
• Never use fuel-powered equipment indoors without appropriate hazard controls.
• Use CO monitoring whenever conditions indicate that hazardous concentrations could develop.
• Headache, dizziness, nausea, weakness, confusion, and drowsiness may indicate CO exposure.
• If CO exposure is suspected, leave the area immediately and seek appropriate medical attention.