Health effects of exposure to ambient carbon monoxide

Abstract Atmospheric trace gases such as carbon monoxide (CO) are essential for the healthful function of the Earth’s plants, animals, and natural environment. Biological organisms not only adapt to background levels of CO, but also produce and utilize CO for normal life processes. Increasing concentrations of CO from man-made sources became a public health problem, however, when levels disturbed the established natural balances. Unfortunately, the common atmospheric gases are not always taken seriously as environmental “pollutants”. Concerns about the potential health effects of exposure to CO have been addressed in extensive studies with various animal species as subjects. Under varied experimental conditions, considerable information has been obtained on the toxicity of CO, its direct effects on blood and other tissues, and the indications of these effects in the form of changes in organ function. The lethality of CO that results from extremely high concentrations is well known, but other effects of CO often are overlooked, especially in susceptible individuals. The health effects of low concentrations, such as levels found in ambient air, are far more subtle and considerably less threatening to the general public.