By Griggs TR.
Journal of Occupational Medicine. 1977 Nov;19(11):759-61.

The firefighter's exposure to carbon monoxide represents a relatively contant occupational hazard. Unfortunately, attempts to predict the level of this exposure in work situations have failed to be of practical benefit. This study was designed to examine the several determinants of carbon monoxide uptake by firefighters in a controlled situation.

Twenty firefighters were monitored for heart rate and carboxyhemoglobin (COHb) levels during a search-and rescue drill in a smokefilled building. Carbon monoxide levels were maintained at 200 to 1000 ppm. Heart rates increased to 90% of maximum for age within minutes, and COHb levels increased at more than 1% per minute. The use of breathing apparatus provided full protection from uptake of COHb but was associated with significantly increased heart rates.

The results show that exertional levels and, therefore, ventilatory rates may be so great during firefighting that even in moderate or low levels of atmospheric carbon monoxide the COHb can rise to dangerous levels within minutes. These findings suggest that no firefighter should be allowed to work in a burning or smoke-filled structure without the protection of breathing apparatus.