In an effort to control air pollution, the EPA uses a Command and Control system of enforcement. That is, the government sets levels that industry is required to meet and then enforces those standards. With a few exceptions, history shows that this is usually effective.
Industry points out the problem of risk assessment .
He questions whether the cost we bear is worth the protection we gain. There is often a great deal of disparity here. The Clean Air Act requires the EPA to review and possibly revise standards every 5 years and subsequently propose new measures. Revisions are based on the presence of new scientific discoveries, or evidence, that support a such action. Under the Clean Air Act, NAAQs set the safety level for six criteria pollutants.