Carbon Monoxide and Human Vigilance

Abstract

This study was conducted to determine whether carbon monoxide gas is a factor responsible for deterioration of vigilance in men breathing polluted air. Ten subjects were exposed for slightly longer than two hours, on separate occasions, to CO levels approximating the average (26 ppm) and peak (111 ppm) levels found while driving in urban traffic. During the last hour of each exposure the subjects undertook a, standard test of visual vigilance. They also undertook the test while breathing air without CO. Blood carboxyhemoglobin levels were measured prior to exposure, before and after the tests. Heart rates and minute ventilatory volumes were also measured The results showed that vigilance was impaired by breathing 111 ppm CO which raised the average COHb level to 6.6.% Heart rates and minute ventilatory volumes were not affected.