Effect of low level carbon monoxide on compensatory tracking and event monitoring.

Experiments by Putz et al. concerning the effect of carbon monoxide (CO) exposure on compensatory tracking and monitoring in healthy young men were replicated. Task and procedural variables were reproduced as closely as practical. Subjects were exposed to either room air or 100 ppm CO. Mean carboxyhemoglobin (COHb) levels in the high CO exposure groups were 5.1% for Putz et al. (70 ppm exposure), and 8.24% for the present study (100 ppm exposure). In both studies elevated COHb produced a statistically significant increase over time in log mean absolute deviation scores (tracking error) with respect to control groups. The magnitude of the effect was smaller in the present study, perhaps because of subtle methodological or training differences between studies. The relationship between task difficulty and magnitude of CO-induced dysfunction remains unresolved. In contrast to Putz et al., no statistically significant effect of COHb in monitoring behavior was found. The failure to replicate this feature of may reflect the large differences in baseline performance, and higher variance in the present study.