35ppm Headache/dizziness w/in 6-8hrs of constant exposure
100ppm Slight headache in 2-3 hours
200ppm Slight headache in 2-3 hours
400ppm Frontal Headache w/in 1-2 hours
800ppm Dizziness, nausea and convulsions w/in 45 minutes
1,600ppm Headache, dizziness, nausea w/in 20 minutes. Death within 2 hours
3,200ppm Headache, dizziness, nausea w/in 20 minutes. Death within 30 minutes
6,400ppm Headache, dizziness, nausea w/in 1-2 minutes. Death in less than 20 minutes
12,800ppm Unconsciousness after 2-3 breaths. Death in less than 3 minutes (above this level, it is also flammable)
Carbon monoxide is colorless, tasteless and just slightly lighter than air. Your best defense is a functioning CO detector and checking all systems that use combustible materials for fuel.