A Possible Scenario
Based on our analysis, which used empirical data, it appears that when control strategies are implemented, the "piston" effect will result in the higher hourly average concentrations to be reduced faster than the mid-level values. Similar to the results obtained for the hourly values, the rate of decline for the 8-hour daily maximum values in the mid range will be much slower than the higher 8-hour values. The next figure illustrates the slowing down process for Fairfield County, Connecticut. Note the rapid decrease in the early years and then a "flattening" of the curve in the later years.