Carbon Monoxide (CO)
Carbon Monoxide (CO): Risks, Detection, Exposure and Monitoring
What is carbon monoxide (CO)?
Carbon monoxide (CO) is a highly toxic, colorless, odorless gas produced by the incomplete combustion of fuels such as gas, oil, and wood. Even at low concentrations, it can interfere with the body’s ability to transport oxygen, leading to serious illness or death. Because it cannot be detected by human senses, carbon monoxide must be monitored using specialized gas detection equipment.
Carbon monoxide forms when carbon-based fuels do not burn completely due to a lack of oxygen. It is commonly generated by:
- Engines and generators
- Heating systems
- Industrial combustion processes
Because it is invisible and has no smell or taste, it is often referred to as a “silent killer.”
Why carbon monoxide is dangerous?
When carbon monoxide is inhaled, it binds with hemoglobin in the blood to form carboxyhemoglobin, reducing the blood’s ability to carry oxygen.
This prevents oxygen from reaching vital organs such as:
- The brain
- The heart
The effects depend on both the concentration of carbon monoxide and the duration of exposure.
Symptoms of CO poisoning include:
- Headache or dizziness
- Shortness of breath
- Nausea
- Loss of consciousness
- Fatigue
- Chest or abdominal pain
- Confusion or erratic behavior
- Visual disturbances
Severe exposure can result in coma or death.
Where is carbon monoxide found?
Carbon monoxide is commonly found in a wide range of environments:
Industrial environments
CO is produced as a byproduct of combustion and can be generated during a variety of industrial processes, including:
- Steel production
- Cement manufacturing
- Chemical production
- Fossil fuel combustion
Gas monitoring systems are used in these environments to detect and measure CO and other pollutants, helping maintain regulatory compliance and protect workers and nearby communities.
Marine & confined environments, including submarines
Maintaining safe atmospheric conditions inside a submarine is critical to the safety, health, and wellbeing of onboard personnel.
CO can be produced onboard through several sources, including:
- Engine exhaust - generated by diesel engines and fuel cells used for propulsion and power
- Generator exhaust - produced during electricity generation
- Cooking activities
- Fire and smoke incidents onboard
- Incomplete combustion of chlorate candles, which can result in CO leaks
Diving applications
Breathing air compressors rely on clean atmospheric air to safely fill diving cylinders.
Carbon monoxide can be introduced into diving environments in several ways, including:
- Diving equipment - CO generated by compressor engines can contaminate breathing air systems
- Dive boats - engines and onboard generators can produce CO that may enter surrounding air intake systems
- Rebreather systems - chemical reactions within closed-circuit rebreathers can potentially lead to CO buildup within the breathing loop
General environments
- Poorly ventilated buildings
- Areas containing combustion equipment
How carbon monoxide is detected
Carbon monoxide is measured using specialized sensing technologies, including:
Electrochemical sensors
Electrochemical carbon monoxide sensors use a chemical reaction to measure the concentration of CO gas in the air.
The sensor typically consists of three main components:
- The sensing electrode, coated with a material that reacts with CO gas and produces an electrical current proportional to the amount of CO present
- The reference electrode, which provides a stable voltage reference
- The electrolyte, a liquid or gel that allows ions to flow between the electrodes
When carbon monoxide comes into contact with the sensing electrode, a reaction occurs that generates an electrical current. The strength of this current is proportional to the concentration of CO in the air. The reference electrode and electrolyte maintain stability within the sensor, allowing accurate measurement of carbon monoxide levels.
Infrared (GFC) sensors
Infrared (IR) gas filter correlation (GFC) sensors measure carbon monoxide by analyzing how CO absorbs infrared light.
These sensors typically include:
- An IR light source, such as an LED or laser, that emits infrared light through the air sample
- An IR filter designed to pass a specific wavelength associated with carbon monoxide absorption
- A detector, typically photovoltaic or pyroelectric, that measures the intensity of light passing through the sample
As infrared light passes through air containing CO, some of the light is absorbed by carbon monoxide molecules. The amount of absorption is proportional to the concentration of CO present.
GFC sensors are highly selective and sensitive to carbon monoxide while being less susceptible to interference from other gases. However, they are generally more complex and often more expensive than electrochemical sensors.
Where should CO detectors be installed?
-
Near combustion sources
-
In enclosed or poorly ventilated spaces
-
At breathing height
Proper placement helps ensure early detection before carbon monoxide reaches dangerous exposure levels.
Common safety mistakes
- Assuming CO can be detected by smell
- Poor ventilation in enclosed spaces
- Using incorrect or uncalibrated detectors
- Failing to monitor compressed air systems
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FAQs
Can you smell carbon monoxide?
No, it is odorless and cannot be detected by human senses.
How is carbon monoxide produced?
Through the incomplete combustion of fuels.
Where should CO detectors be placed?
Near combustion sources and in enclosed or poorly ventilated spaces.
Key takeaway
Carbon monoxide is a highly toxic gas that cannot be detected without specialized monitoring equipment. Continuous monitoring is essential in any environment where combustion processes are present.