We present an input-output model which determines the optimal level of economic activities and their optimal emission of air pollutants so as to maximizes the welfare function being subject to the emission standards of the air pollutants with respect to the emission taxes. By making the emission standards strict step by step, we analyze the feasibility and implementability of the reduction scenario by the numerical simulations. We also analyze impact of assumed technological progress in the air pollutant abatement activities on the feasibility of scenarios. In this paper, it is argued that even if the emission taxes are introduced so as to reflect the social cost of the air pollutants, it has potential to increase the GNP and the welfare. However, the cost of reduction in the emission of air pollutants in terms of GNP is large and the welfare rapidly decreases less than generally tolerable level as the reduction rate increases, at least in the short run. We formulate a model of the total environmental economic system which controls the air pollutants emitted by not only industries but also households. The fundamental of the model is the non-linear dual system of the input-output analysis. The model is applied to the Japanese economy in 1995. Thirty two industries are distinguished, and three types of pollutants, CO₂, SO _x and NO _x are analyzed. From this research, we obtain that, to achieve a great abatement of emission like made in the Kyoto Protocol, the technological progress in the abatement industries is an important key factor. A fairly large amount of R & D investment into the abatement technology and related sciences will more pay than ever thought generally. And, to reduce the air pollutants emission by 15% less than the actual level in 1995 should have been a fairly strict goal at least in the short run. To consider other sources of the gases, it is almost in feasible unless the abatement technology progresses rapidly.