percent. Thus, in the future as controls rise above present level, total pollution costs would be relatively less burdensome.
If pollution policy develops over time as we think it might--somewhere between what we have called the relaxed and the strict cases-- environmental damages resulting from the mass pollutants covered in this chapter are likely to remain the same or fall over time despite the growth in the economy and greater number of people at risk. They would rise somewhat if the relaxed policy were pursued while the economy grows at the most rapid of the rates considered, but they would fall under either the relaxed or the stringent policy if the rate of growth were lower. In all cases, after 1985 they fall over time on a per capita basis and as a percentage of consumption.
Pollution control costs, though never a large percentage of GNP, will increase over time relative to both population and economic growth in all scenarios. The net effect is that total costs (damage plus control costs) as a percentage of GNP or of consumption remain roughly the same or fall slowly over time. The result is similar for scenarios with high rates of population and economic growth and those with low rates of growth. Though the mass of pollutants to be treated differs significantly among scenarios, the appropriate level of controls to minimize total costs and the cost of control as a percentage of the GNP do not differ greatly. Clearly, control policy is central to achieving acceptable levels of environmental quality; indirect approaches that would alter population and economic growth can have little impact on their own.
The policies we have analyzed, and which we believe to be most likely, are based on uniform national emission standards. In fact, some regions will be "overcontrolled," while others could experience deterioration in environmental quality; and some industries will find the costs of meeting control regulations rising rapidly, while others are not seriously burdened. Differential standards for special regions and some means of easing the transition for especially hard-hit sectors and regions would be worthy of serious consideration.
A possible example of "overcontrol" in some regions may be regulations on CO and NO. from transportation. Our analysis of these pollutants suggests that control levels may be set far above the point of