Dust counting Critical review and presentation of vermont practice

Counting respirable dust particles using bright field microscopy has been the classic approach for rapid practical evaluation of the dustiness of workplace atmospheres. The technique has been beset with difficulties arising out of variations in the optical systems and the counting cells used by various laboratories. This paper reviews the history of the technique and some of the problems which have been encountered. It also details the method used by the Vermont Division of Occupational Health for the past 20 years to count dust, describing the easily reproducible optical system and the use of a “thin” hemocytometer cell employed.