Poster: Carbon Monoxide
Poster: Carbon Monoxide Poster (Spanish)
Fact Sheet: Carbon Monoxide (Spanish)

Carbon monoxide (CO) is a colorless, odorless, tasteless gas with a molecular weight of 28.

CO is generated when organic material is heated or burned with a limited supply of oxygen.

High levels of CO may be found in and around:
• Fires
• Petroleum refining
• Coal refining
• Blast furnaces in metal refining
• Vehicle exhaust
• Some welding operations
• Cigarette smoke
• Burning or combustion processes

Fossil fuel vehicles (autos, forklifts) can be a primary source of CO in enclosed or poorly-ventilated areas (garages, auto shops, warehouses, underground parking lots, and tunnels).

Toxicology and Symptoms of Exposure
CO is toxic through inhalation and has no warning properties (smell, taste). It affects the body’s ability to carry oxygen molecules to the cells, and thus is considered a chemical asphyxiant. CO binds readily to the oxygen carrying protein in the blood (hemoglobin). Hemoglobin’s affinity for CO is estimated to be over 200 times that for oxygen.

Exposures to CO above 1000 parts per million (PPM) can cause loss of consciousness and death. Typical symptoms at exposure levels above the OSHA permissible exposure limit (PEL), or 50 parts per million (PPM), may include headache, nausea, vomiting, dizziness, weakness, rapid breathing, mental confusion, and a cherry-red coloration of the skin.

The general treatment for CO poisoning is to remove the source and provide fresh air to the affected person while keeping them at rest. Medical treatment may include administration of enriched oxygen or treatment in a hyperbaric oxygen chamber. It is important that all CO poisoned persons receive a medical check up and/or treatment following overexposure.

Fossil fuel vehicles should be used in areas with adequate mechanical or natural ventilation. Properly-adjusted combustion sources put out less CO emissions. As a general rule, propane- and diesel-fueled vehicles exhaust far less CO than gasoline-fueled vehicles. CO monitoring is also recommended for high-traffic and poorly-ventilated areas, as well as confined spaces.

Exposure Limits
The OSHA PEL for CO is 50 PPM averaged as an eight-hour time weighted average (TWA). A ceiling limit (exposure level that should never be exceeded regardless of eight-hour TWA) of 200 PPM has been set by the National Institute of Occupational Safety & Health (NIOSH). The American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value is 25 PPM as an eight-hour TWA. A level of 1200 PPM has been designated by NIOSH as immediately dangerous to life or health (IDLH).

Additional Resources
WCF Insurance Safety Department
(385) 351-8103

Ask a Safety Consultant

NOTICE: This guide may make reference to the Occupational Safety and Health Administration (OSHA) regulations; however the guide is not legal advice as to compliance with OSHA or other safety laws, codes, or regulations. Compliance with OSHA and other safety laws codes or regulations, and maintaining a safe work environment for your employees remains your responsibility. WCF Insurance does not undertake to perform the duty of any person to provide for the health or safety of your employees. WCF Insurance does not warrant that your workplace is safe or healthful, or that it complies with any laws, regulations, codes, or standards.