A high level of CO for a short period (e.g. 350 ppm CO for 30 minutes) will cause the same symptoms,
a slight headache, as a lower level for a longer time (e.g. 150 ppm for 90 minutes). Table A shows how
exposure to different concentrations of CO generally affects people.
Many cases of reported Carbon Monoxide poisoning indicate that while victims are aware they are not
well, they become so disorientated they are unable to save themselves by either leaving the building or
calling for assistance. Young children and household pets may be the first affected.
Table A: Effects of Carbon Monoxide Poisoning
35
The maximum allowable concentration for continuous exposure in any 8 hour period according to OSHA *.
150
Slight headache after 1.5 hours.
200
Slight headache, fatigue, dizziness, nausea after 2-3 hours.
400
Frontal headaches within 1-2 hours, life threatening after 3 hours, also maximum parts per million in flue gas (on an
air free basis) according to US Environmental Protection Agency.
800
Dizziness, nausea and convulsions within 45 minutes. Unconsciousness within 2 hours. Death within 2-3 hours.
1,600
Headache, dizziness and nausea within 20 minutes. Death within 1 hour.
3,200
Headache, dizziness and nausea within 5-10 minutes. Death within 25-30 minutes.
6,400
Headache, dizziness and nausea within 1-2 minutes. Death within 10-15 minutes.
12,800
Death within 1-3 minutes.
ppm
Concentration
of CO in Air
Inhalation Time (approx) and Symptoms Developed
ppm = parts per million
*OSHA Occupational Safety & Health Association
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