This set of guide­lines is based on the pre­cau­tion­ary prin­ci­ple and pri­mar­ily intended for use in eval­u­at­ing sleep­ing areas. It is based on sci­en­tific stud­ies that show the low­est level of expo­sure at which adverse bio­log­i­cal reac­tion can be observed, as well as col­lec­tive build­ing biol­ogy case stud­ies and field expe­ri­ence, with an aim toward an achiev­able goal.