Inherent in the ability to accurately assess the performance of a material exposed in the atmosphere is an understanding of the relative corrosivity of that environment. The most reliable of present test methods for ranking materials' corrosion behavior have necessarily utilized long-term exposures to the natural environment in question. Given the variable nature of many atmospheric factors, it becomes important to determine the relative stability in the corrosivity of an atmospheric exposure site. Only in this way can the desired credence be given to atmospheric corrosion data generated for a variety of materials over an extended duration.

A review is provided of the major factors which must be considered in establishing a program to monitor and calibrate an atmospheric test site. These factors include both environmental assessments and corrosion evaluations. Consideration is given to the specific environmental parameters which could be monitored as well as experimental procedures which affect the atmospheric corrosion behavior of materials.