Carbon monoxide and human performance in a single and dual task methodology.

Does carbon monoxide (CO) exposure limit man's ability to time share two concurrent tasks? In our study 15 subjects underwent two different 2.5-h exposures to either filtered air or to 100 ppm CO. They performed two tasks singly and in combination. The central task was a compensatory tracking task with three levels of difficulty, whereas the peripheral task was a signal detection task with three probabilities of signal occurrence. When HbCO levels reached 5% (during the last half hour of the exposure) performance on the peripheral signal detection task was altered. This was demonstrated by a 6% decline in signals detected correctly (p less than 0.05). This decline in signals detected was found when the signal detection task was performed alone. These results suggested that exposure to CO decreased arousal and interacted with fatigue to produce decreases in performance.