| CO Parts per million (ppm) |
Inhalation time (approx) and symptoms developed |
| 35ppm |
The maximum allowable concentration for continuous exposure in any 8 hr period according to HSE |
| 150ppm |
Slight headache after 1 ½ hrs |
| 200ppm |
Slight headache, fatigue, dizziness, nausea after2-3 hrs |
| 400ppm |
Frontal headache within 1-2 hrs, life threatening after 3 hrs |
| 800ppm |
Dizziness, nausea and convulsions within 45 minutes. Unconsciousness within 2 hrs. Death within 2-3 hrs |
| 1600ppm |
Headache, dizziness and nausea within 20 minutes. Death within 1hr |
| 3200ppm |
Headache, dizziness and nausea within 5-10 minutes. Death within 25-30 minutes |
| 6400ppm |
Headache, dizziness and nausea within 1-2 minutes. Death within 10-15 minutes |
| 12800ppm |
Death within 1-3 minutes |
