The AirPhoton 8-slot filter cartridge is a unique design that holds and protects 8 particle sampling filters. This design minimizes the handling of the filters in the field and reduces the frequency of site visits by technicians. Used in conjunction with the AirPhoton Explorer Automated Filter Sampling Station, the cartridge can be deployed through 8 sampling cycles (one of which can be a blank for reference) before exchange with a fresh cartridge is necessary. Each of the 8 slots can hold either 1 filter for straightforward measurements of particles of one size, or 2 sequential filters of different pore sizes for separation of particles by size. When used with the dual inlet system and control box each inlet can be used separately for four sampling cycles. One filter location for each flow can be used as a reference blank.