CARBON MONOXIDE IN THE WORKPLACE
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365-BSA-01-IMOT © 2024, Workplace Safety & Prevention Services (WSPS)
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What does carbon monoxide do while in the body?
Carbon monoxide interferes with the ability of the blood to transport oxygen. Haemoglobin, a protein
present in the red blood cells, normally binds oxygen (to form oxyhemoglobin) and transports it to
all parts of the body. Carbon monoxide competes with oxygen and binds to haemoglobin (to form
carboxyhemoglobin or COHb) much more easily. Carbon monoxide is therefore a chemical asphyxiant.
This means that it prevents sufficient oxygen from reaching the tissues of the body (see Table 4 below).
Insufficient oxygen can cause DEATH.
Table 4: Effects of Varying Levels of Carbon Monoxide
CO Level
Effects
PPM in Air % COHb in
Blood
1-3 0.7-0.8 Normal
25
Time Weighted Average (8 hrs.)
Source: Control of Exposure to Biological or Chemical Agents
Regulation. https://www.ontario.ca/page/current-occupational-
exposure-limits-ontario-workplaces-under-regulation-833
30-60 5-10 Exercise tolerance reduced; heavy smoker has these levels or
higher. Ten percent COHb is maximum allowable body burden
60-150 10-20 Frontal headache. Shortness of breath on exertion
150-300 20-30 Throbbing headache, dizziness, nausea, manual dexterity
impaired
300-650 30-50 Severe headache, nausea and vomiting, confusion and collapse
700-1000 50-65 Coma, convulsions
1000-2000 65-70 Heart and lung function impaired, fatal if not treated
Over 2000 Over 70 Unconsciousness and death
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