ABSTRACT
We can distinguish between two types of pollutant discharge:
(a) Pollution due to current discharge of residuals; (b) Pollution due to residuals discharged in the past. The first kind may be said to be due to day-to-day flow of residuals. This might, for example, be air pollution, where the damage this type of air pollution inflicts on the individual at a given point of time is independent of how much of this air pollution previously existed. This form of pollution has been the object of the greatest concern in public debate. When pollution is due to the accumulation of residuals discharged at a previous point of time, it becomes particularly necessary to study pollution on a long-term basis. Today's discharges will then produce negative effects in the future.
