Citing concerns for public health and welfare, the USEPA has proposed new regulations under the Clean Air Act that impose tighter controls on emissions to the air of particulate matter and ozone producing substances, such as volatile organic compounds and nitrogen oxides. If adopted, the states will be required to revise their State Implementation Plans to address these stricter controls. These revised standards, when implemented by the states, are likely to affect the utility, petroleum, mining, iron and steel, automobile, and chemical industries, as well as other manufacturing concerns that emit particulate matter or precursors to particulate matter or ozone. The extent of these effects will depend upon the implementation policies and strategies adopted by the states in response to USEPA's demand for more stringent controls.