Breakthrough intended to provide an estimate of the service life for air purifying respirators based on the latest scientific information. The accuracy of this estimate will depend on the accuracy and completeness of the data entered by the user. The program is intended as a tool to help an industrial hygienist or a qualified person to set cartridge changeout schedules. It is not a replacement for regulatory requirements or professional judgments. Also, the current version of the program can only handle calculations related to a single organic vapor. Please note the expiration date of this version for the Breakthrough program (December 31, 2006). The purpose of the expiration date is to encourage users to obtain the latest versions of the software and updated databases.