The Air Pollution Control Law was passed in 1968 to replace the Smoke and Soot Regulation Law. Emission standards that were earlier determined by emission concentration regulation were now based on emission volume regulation that took into consideration the effects on the atmosphere. All regulations, however, were for individual facilities, and proved to be insufficient for conditions at Yokkaichi, where a large number of factories were concentrated.
In 1971, Mie Prefecture took a major step towards improving air pollution in Yokkaichi by becoming the first prefecture in Japan to establish regulation on the Total Pollutant Load Control of sulfur oxides (SOx).
Based on the Total Pollutant Load Control, methods to first simulate environmental concentration (to calculate the concentration of atmospheric pollutants) in the area were first established. Target concentration levels for the area were then set and permissible emission levels to achieve the target determined. Based on this, regulations were placed on emissions from each factory in the area.
This chart was drawn up to simulate the environmental concentration in the Yokkaichi area, based on the Total Pollutant Load Control by Mie Prefecture.
Measures to achieve the reduction targets were commenced in fiscal 1972 and completed a year ahead of the originally scheduled date in fiscal 1977. Through these measures, emissions of sulfur oxides (SOx) in the Yokkaichi area were reduced drastically.