file (7) combined with its uniform distribution in urban and nonurban locations. This is clearly demonstrated in Figure 2 where the levels of CC14 in New York City and the White Face Mountains are remarkably similar. The corresponding data for the other halocarbons show their expected much higher urban levels.
Acknowledgment The authors wish to thank Dr. George Wolff (Interstate Sanitation Commission, N.Y.) and Dr. W. N. Stasiuk (N.Y. State Department of Environmental Conservation) for their help in arranging some of the field studies.
Conclusions
Literature Cited
The halogenated compounds studied are primarily anthropogenic and exhibit wide fluctuations in concentrations as a function of location and meteorological factors. However, typical halocarbon ranges at different locations can be inferred from the data base presented here. CC13F, CC12F2, CH3CCl3, and CC14 were ubiquitous atmospheric constituents. Their concentrations in the rural areas were typically in the sub-ppb range and urban concentrations were generally much higher. The first three compounds are of known anthropogenic origin but the cc14 atmospheric budget is inconsistent with direct anthropogenic emissions. The ubiquitous compounds and CC12F-CClF2 are tropospherically stable and will experience their ultimate fate in the stratosphere. Among the tropospherically reactive halocarbons, CpCl4 and C2HC13 should lead to the formation of large quantities of phosgene in the atmosphere that may have a potentially significant impact. It has been demonstrated that halocarbons can be used as excellent tracers of urban transport. Additionally, studies of the temporal and spatial distributions of halocarbons in nonurban areas should help to differentiate between the natural synthesis, urban transport, and stratospheric injection of ozone. Because of the possible stratospheric ozone destruction by stable halocarbons, the toxicity of phosgene, the indicated carcinogenicity of vinyl chloride and its structural similarity to other ambient chloro-ethylenes, and the unknown long-term effects of halogenated compounds and their reaction products, further research in this area is clearly warranted.
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