ABSTRACT
This chapter describes the airspace regime, which had the potential of becoming a global commons regime but did not. One of the limits of national airspace was that sovereign airspace was usable airspace, that portion of the atmosphere above a nation in which aircraft could operate. The chapter provides the background explaining why resolution of issues involving atmospheric pollution is so dependent on national legislation and compliance. It examines atmospheric pollution in three critical areas: acid deposition, global climate change, and stratospheric ozone depletion. Ultraviolet radiation from the sun is both mutagenic and carcinogenic, and stratospheric ozone prevents 99 percent of ultraviolet radiation from reaching Earth. Why is the ozone layer so susceptible to loss? The answer lies in the peculiar chemical properties of chlorine free radicals, a breakdown product of chlorofluorocarbons. Seasonal loss of ozone over the Antarctic in 1992 and 1993 was near total at some altitudes, and the long-term impact on the Antarctic food chain is troubling.
