RISK INSIGHT: Carbon Monoxide – The Quiet Killer

Property & Casualty, Risk

Carbon monoxide (CO) is an odorless, tasteless, colorless gas that, given the right conditions (or wrong conditions for that matter), can create hazardous environments dangerous to human health. Carbon monoxide is not only a potential dangerous gas in the workplace, but also at home and in the office. It is almost undetectable and invisible, and, when inhaled at high concentrations, can result in severe adverse health effects up to, and including, death.

Key Facts about Carbon Monoxide

  • The CDC states that approximately 50,000 people in the U.S. visit the emergency room annually due to accidental CO poisoning.
  • Approximately 430 people die each year from accidental CO poisoning according to the CDC.

Where will I find Carbon Monoxide in my home, office, or workplace?

Carbon monoxide is a component of incomplete combustion and is commonly found in industrial environments resulting from a variety of sources. Some examples include: liquid propane (LP)-powered industrial equipment such as forklifts, man-lifts, and booms, as well as gasoline-powered equipment such as portable generators and tools. Natural gas heat sources are another common contributor of CO exposures if operating inefficiently or not properly maintained. This may include: ovens, furnaces, air-handling units, direct-fired heaters, and boilers.

Office and residential settings can also be at risk. Natural gas-fired furnaces, stoves, ovens, water heaters, and other fuel-burning heat sources have the potential to off-gas CO if running poorly, are neglected, or not maintained properly. Gas-powered equipment such as snow blowers, snowmobiles, ATVs, and even vehicle exhaust can be problematic in the winter months if running for extended periods of time in enclosed spaces such as garages or sheds.

What are the signs and symptoms of exposure?

Common symptoms include the following:

  • Headache
  • Dizziness
  • Nausea
  • Confusion
  • Chest pain
  • Weakness
  • Upset stomach

The above symptoms can dissipate and self-correct if the individual(s) are removed from the area into fresh air (e.g. outdoors). However, these symptoms can be mistaken for other health-related conditions and, if left unchecked, can lead to severe consequences with little warning especially in confined spaces or other enclosed areas with very little fresh air infusion.

How to prevent Carbon Monoxide poisoning? 


  • Ensure proper preventative maintenance is performed on all equipment that is fuel-burning. Examples include: CO emission measurements as part of your LP powered forklift maintenance, CO emission control devices, and annual air-handler/furnace tune-ups prior to the winter months.
  • Ensure adequate dilution ventilation in an industrial environment. The American Conference of Governmental Industrial Hygienists (ACGIH) recommends 5,000 cfm of fresh air infusion per LP powered forklift and 8,000 cfm per gasoline powered forklift.
  • Install CO monitors with audible alarms and calibrate the monitors per the manufacturer specifications (e.g. annually).
  • When working in confined or enclosed spaces, ensure personal CO monitors are worn to alert individuals if elevated CO concentrations are detected.
  • Consider electric-powered forklifts and similar equipment to eliminate the CO source as a long term capital improvement project.


  • Perform annual or more frequent scheduled maintenance on natural gas-fired air-handlers/furnaces utilizing a qualified HVAC contractor. Prior to the winter months, it is ideal to ensure the systems are operating at peak efficiencies and to provide early detection of deficiencies.
  • Install CO monitors (if not already in place). Best design set-ups are hard wired with battery back-ups. Replace back-up batteries on an annual basis. A good rule of thumb is to replace the batteries in concert with daylight savings.
  • In office environments, maintaining adequate fresh air infusion can also prevent CO build-up, among other benefits including improved indoor air quality and minimal occupant comfort concerns.

What if I think there is a CO problem?

  • Immediately leave the area. Go outdoors or to another area of known fresh air.
  • Call 9-1-1 and do not reenter the space until safe to do and directed by local authorities (e.g. Fire Department).

Early intervention can be life-saving. Be aware of potential for CO exposure, and don’t ignore signs or symptoms. Contact your M3 Account Executive or Risk Manager to learn more about strategies to prevent CO overexposure in your workplace or at home.

Back to Insight Center