Gaseous air cleaners that are most practical and effective for indoor applications consist of granular adsorbents, with or without special impregnations. The nonpolar adsorbent of choice is activated carbon; polar adsorbents include activated alumina, silica gel, and surface-active clays.

This paper describes an air sampler that consists of 16 cylindrical cartridges manifolded in a 4 by 4 pattern. The sampler may be used in any of three modes: to test a given adsorbent for its service life in any particular indoor environment, to set up competitive tests between different adsorbents or impregnations, or to test a partially saturated adsorbent for its residual efficiency.