Peroxyacetyl Nitrate (PAN): Historical Perspective

Peroxyacetyl nitrate (PAN), an important intermediate in the photochemical production of ozone, acts as a reservoir for NO2. An overview of the history of PAN's discovery and its connections to the plant damage observed in the South Coast Air Basin of Southern California will be presented. The work done by pioneers in this research area will be the focus, particularly the long-path infrared spectroscopy and electron capture detection chromatography measurements that enabled further exploration of PAN chemistry. The period from the 1950s to the present will be briefly highlighted, including synthetic procedures, measurement techniques, laboratory properties (rates of reaction, ultraviolet photolysis, aqueous solubilities), and field measurements. The work summarized has led to the determination that PAN and its analogs play key roles in urban, regional, and global tropospheric chemistry. The phytotoxicity of PAN will also be discussed, along with its connections to other key trace species, namely the organic peracids, peroxides, and nitrates.

This work was supported by the U.S. Department of Energy, Office of Biological and Environmental Research, Atmospheric Chemistry Program, under contract W-31-109-Eng-38.