"FOREWORD The first part of this addendum is part of a larger plan to combine Standards 52.1 and 52.2 into a single standard on air filter testing. It incorporates the 52.1 sections on arrestance and dust-holding capacity into Standard 52.2 and deletes some references to Standard 52.1 that occur in Standard 52.2. Future addenda will complete the process of making Standard 52.2 self-sufficient and comprehensive@ and at this time SPC 52.1 will be able to withdraw Standard 52.1. While similar to previous definitions@ the terms arrestance and dust holding capacity are procedurally different and should not be directly compared to prior definitions in previous versions of Standard 52. Part 2 of this addendum adds a new informative appendix to Standard 52.2@ Appendix J. Appendix J provides an optional method of conditioning a filter using fine KCl particles to demonstrate efficiency loss that might be realized in field applications. When Standard 52.2-1999 was published@ the project committee recognized that the conditioning step@ also called the first dust-loading step@ was not fully adequate for revealing the drop in efficiency that some filters undergo during actual use. This is pointed out in the standard's foreword: ""The initial conditioning step of the dust-loading procedure described in this standard may affect the efficiency of the filter but not as much as would be observed in actual service."" This is further discussed in Appendix A of the standard (A2.2 and A2.3) where it is stated that ""ASHRAE Technical Committee 2.4 has funded a research project to develop a loading dust for a new loading test method that will more nearly represent the minimum efficiency points in actual real-world use."" This procedure is an outcome of that research project (ASHRAE RP-1190@ ""Develop a New Loading Dust and Dust Loading Procedures for the ASHRAE Filter Test Standards 52.1 and 52.2"") and ASHRAE RP-1189@ ""Investigation of Mechanisms and Operating Environments that Impact the Filtration Efficiency of Charged Air Filtration Media@"" and subsequent committee action. The procedure described in Informative Appendix J is the result of project committee revisions in response to comments received during two public reviews of the procedure. Since these revisions@ however@ the procedure has not been issued for another public review@ and Appendix J is not ANSI approved. "