Systems, methods, and devices for an end of service life indicator for a respirator are described herein. For example, a device can include a cartridge containing a filter material and an insert extending through at least a portion of the filter material having a first path with a first opening to provide a sample of air that is representative of a saturation of the filter material and a second path with a second opening configured to provide a filtered sample of the air throughout a service life of the cartridge.