The need for an inexpensive, direct reading, personal monitor to measure employee exposure to workplace atmospheric contaminants still exist. A passive monitor using variable length orifices and the principle of diffusion was designed and investigated. A colorimetric media fixed at the end of the orifices was used to indicate contaminant relative concentration. The system was tested with Hydrogen Chloride, Sulfur Dioxide, and Ammonia as atmosphere contaminants. The system showed a graduated response in relationship to the increasing orifice lengths. Parallel scale alignment charts were prepared to allow interpretation of the monitor readings by the individual employee. It is felt that the use of a system of this nature would meet the needs of industry to provide employee exposure information at an acceptable cost.