In general, carbon monoxide is a colorless, odorless, tasteless gas that can result in asphyxiation by preventing oxygen transport in the blood. It is created from incomplete combustion from burning fuels or microbial decomposition or organic matter in sewers, silos, and fermentation tanks.

At 200 ppm exposure for a few hours, mild frontal headache may be experienced. At 400 ppm, headache and nausea can occur. At 800 ppm, headache, dizziness, and nausea may occur after 45 minutes of exposure and possible collapse and death in 2 hours. At 1600 ppm, headache, dizziness, nausea in 20 minutes, and possible collapse and death in 1 hour. At 3200 ppm, headache and dizziness in 5-10 minutes and unconsciousness and danger of death in 30 minutes. At 6400 ppm, headache and dizziness within 1-2 minutes and unconsciousness and danger of death in 10-15 minutes. An at 12800 ppm, immediate effects such as unconsciousness and danger of death in 1-3 minutes.

Continuous air monitoring is the best means of protection. Detecting early signs and symptoms of exposure and getting to fresh air can also prevent overexposure.