This report reviews the progress made by EPA from March 1978 to August 1979 in regulating ozone depleting substances. In March 1978 EPA along with Food and Drug Administration (FDA) issued final rules prohibiting the manufacturing and processing of chlorofluorocarbons (CFCs) for nonessential aerosol propellant uses. EPA continues its investigation of nonaerosol and miscellaneous CFC uses, including use as refrigerants, foam blowing agents, cleaning agents in the electronic and metal industries and as solvents. The EPA study includes several regulatory strategies to reduce CFC emissions, namely, (1) direct regulation, (2) economic incentives and (3) a conservation program. Because CFC emissions in any country may have adverse effects globally, the reduction of CFC emissions is an international concern. EPA is developing programs to investigate other substances or chemicals that may deplete the stratospheric ozone. In implementing the Clean Air Act and deciding whether and to what extent further regulation is necessary, EPA is continuing its studies of current developments in ozone processes, of adverse health and environmental consequences of ozone depletion, of technological capability to reduce emissions from major sources, and of the cost of achieving control.