Some topics discussed are: relationship of carbon monoxide emission to ambient levels and levels in the human population; location of monitoring stations; effects on the central nervous system and cardiovascular system; use of epidemiologic methods to determine clustering of heart attacks by states or by time; amount of CO in blood of individuals dying of arteriosclerotic heart disease in comparison to those dying of other causes; relationship between amount of smoking and amount of carboxyhemoglobin; and thiocyanate levels in blood of myocardial infarction patients. (HLW)