Carbon monoxide is one of the main reactive trace gases in the earth’s atmosphere : it influences the atmospheric chemistry as well as the climate. In order to evaluate the atmospheric budget for carbon monoxide, a knowledge of its destruction/uptake rates by the individual sinks is required. In this study, our current understanding of sinks for atmospheric carbon monoxide is discussed. Although the major sinks have been identified estimates for their strengths are still uncertain. Experimental data are available for only a few locations, and more measurements in representative regions world-wide are required in order to evaluate the CO global budget more accurately. Our current understanding of the environmental impacts of carbon monoxide is reviewed. CO is a toxic gas which can cause fatal asphyxiation. However, our knowledge of the effects of exposure to moderate doses of CO on the health and behaviour of humans is limited. Carbon monoxide also contributes indirectly to global warming and ozone depletion. So, there is a need for a better understanding of the atmospheric chemical processes involving CO in order to reduce the uncertainties in the estimates of its impact on the global environment.