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Carbon Monoxide

Who is at risk?

Coal miners are particularly at risk of carbon monoxide poisoning. It is the most dangerous of all gasses which occur in mines and is commonly found after blasting operations and explosions.

Operators of petrol powered machinery or vehicles within an enclosed space are susceptible to carbon monoxide exposure.




Carbon monoxide is an odourless gas and can be particularly dangerous as it is difficult to detect exposure. In addition, inhalation symptoms can be mistaken for the common flu.

Carbon monoxide competes with oxygen and binds to haemoglobin much more easily, preventing oxygen from reaching tissues of the body. Insufficient oxygen can cause death.

Acute Exposure

Concentration Effect
35 ppm Headache and dizziness within six to eight hours of constant exposure
800 ppm Dizziness, nausea, and convulsions within 45 min; insensible within 2 hours
1600 ppm Headache, tachycardia, dizziness, and nausea within 20 min; death in less than 2 hours
6400 ppm Rapid headache and dizziness. Convulsions, respiratory arrest, death within 30 minutes.
12800 ppm Unconsciousness after 2–3 breaths. Death in less than three minutes.

Exposure Controls & Protection

Do not use cartridge or canister respirators because there is no way of knowing that the cartridge/canister is saturated. Airline respirators and self-contained breathing apparatus are recommended.

Leak Detection & Monitoring

As carbon monoxide has no odour and is not visible, the only way to determine its presence and concentration is to sample or monitor the air:

Portable carbon monoxide detectors are essential for monitoring exposure levels to gas in an underground environment.

NFPA 704 Signal

  Hazard Value Description
Health 3 Can cause serious or permanent injury.
Flammability 4 Burns readily. Rapidly or completely vaporizes at atmospheric pressure and normal ambient temperature.
Instability 0 Normally stable, even under fire conditions
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