The emissions of CO2, SOx, and NOx of various steel alloys in the prod
uction stage were calculated by using the unit requirement of each sub
system of the steel-making process, in order to compare the superiorit
y from the viewpoint of the environmental issue among various types of
steel alloys. As steel production is a typical integrated system with
multiproducts, allocation of emissions to each product, effect of the
composition, and sharing the load by the by-product gases are conside
red. Calculated values of emission were arranged for fifteen kinds of
finished steel products and for arbitrary contents of alloying element
s.