Optical instruments are affected during their use by a number of different environmental parameters which they are required to resist without signification reduction in performance and to remain within defined specifications. The type and severity of these parameters depend on the conditions of use of the instrument (for example, in the laboratory or workshop) and on its geographical location. Individual parameters cause a variety of different and overlapping effects on instrument performance. The manufacturer attempts to ensure, and the user naturally expects, that instruments will resist the likely rigours of their environment throughout their life. This expectation can be assessed by exposure of the instrument to a range of simulated environmental parameters under controlled laboratory conditions. This part of DIN ISO 9022 specifies the methods relating to the environmental tests of optical instruments including additional assemblies from other fields (for example, mechanical, chemical, and electronic devices), under equivalent conditions, for their ability to resist the influence of salt mist. Exposure to salt mist mainly results in the corrosion of metals. Effects might also occur by way of clogging or binding of moving parts. The committee responsible for this standard is Working Committee NA 027-01-02-03 AK "Umweltbedingungen und -prüfungen für optische Geräte" ("Environmental requirements and test methods for optical instruments") of Standards Committee Optics and Precision Mechanics at DIN.