Phosgene in the ambient air

Abstract

IN recent years the atmosphere has become contaminated with a large number of halogenated compounds. Whereas inert fluorocarbons are suspect as precursors of stratospheric ozone-destroying chlorine atoms, other halocarbons, such as vinyl chloride, chloroform and trichloroethylene, have been found to be carcinogens^1,2. We present here the first measurements of ambient phosgene (COCl₂), and demonstrate that chloroethylenes (primarily C₂Cl₄ and C₂HCl₃), which are emitted worldwide in extremely large quantities (1.5 × 10⁶ t in 1975), photodecompose to form highly toxic species such as phosgene and chloroacetylchlorides. A consideration of the sources, the distribution, and the fate of these species suggests that a significant environmental impact is possible. The results presented here are based on laboratory and field studies conducted within California in 1976.