A sedimentation plate is a passive air sampler used for the semi-quantitative determination of airborne microbial counts in the pharmaceutical industry. The sedimentation plate contains a culture medium that enables the growth of microorganisms such as bacteria, yeasts and molds. The sedimentation plate is left open in a Cleanroom or other controlled area for a period of time to collect the airborne particles. The sedimentation plate is then incubated to count the visible colonies.