Most reports on air quality trends typically begin with 1970, with the passage of the first Clean Air Act and the beginning of systematic monitoring of emissions and ambient levels of air pollution. Data from early monitors and evidence from air quality models, however, show that many forms of air pollution started to decline—in some cases rapidly—before the Clean Air Act of 1970.
For sulfur dioxide, data from 21 urban monitors show that the average ambient level fell approximately 40 percent between 1962 and 1964, as shown in Figure 1. This set the stage for progress after the Clean Air Act; the national average dropped 66 percent since then. Local data for New York City show that ambient sulfur dioxide fell by almost 50 percent between 1964 and 1970....
Ambient SO2 Level, Mean Annual Average, 1962-1997
Ambient SO2 Concentrations in New York City, 1963-1972
As it is often the case, legislation just puts into law a natural, already recurring response to a problem. Legislators then can take the praise and glory for what would have happened without their involvement and legislation. In most cases, the law passage increases costs, creates unnecessary criminality and creates rigidity where flexibility is often needed.
Legislators and enforcement agencies will be able to cite statistics showing an improvement post passage of the law. However, a trend line starting from before the law's existence will almost always show that the law did not make any improvement over the pre-existing trend.
No comments:
Post a Comment