From March 2008 PERC Reports article “Clearing the Air”:

The public’s interest is in clean-enough air, achieved at the least possible cost. But the Clean Air Act (CAA) regulatory system is mainly about process, rather than results. The CAA and Environmental Protection Agency (EPA) regulations to implement it have created large administrative burdens, economic distortions, and perverse incentives—all of which impose costs on Americans that far exceed what is necessary to merely reduce air pollution to safe levels. Furthermore, there is no end in sight, because the CAA endows the EPA with the power to keep expanding its influence. The EPA sets national air pollution standards, so the agency, in effect, decides when its own job is finished. Naturally, it never will be.