Engineers responsible for controlling contaminants in the workplace need additional analytical procedures to achieve the precision necessary to satisfy Occupational Safety and Health Administration (OSHA) standards. They do not have analytical procedures to predict the concentration of contaminants in the vicinity of the source, yet OSHA requires contaminants to be controlled to concentrations in parts per million. Present design procedures consist of descriptions of control systems that are satisfactory for specific industrial operations but cannot be generalized to arbitrary configurations, such as are generally necessary in the workplace. Guidelines for sizing the ventilation volumetric flow rate and critical dimensions of the control system are also given in the current procedures. While this information is useful for a preliminary design, the designer is unable to make even qualitative estimates of the contaminant concentration in the operator's breathing zone (OBZ) or at other points in the vicinity of the source.

The objective of the present research is to begin to remedy this situation by developing a quantitative tool that will predict contaminant concentrations at locations specified by the designer in grinding booths of arbitrary size and shape. The method is based upon a computer-aided design procedure, which is coupled with computer graphics to enable engineers to (1) specify the shape of the ventilation system by physically drawing it with a light pen on a sensitized tablet; (2) input ventilation flow rates and compute the contaminant concentration at points selected by the designer; and (3) display the results graphically, as well as numerically, so that either the geometry of the ventilation system or the ventilation flow rate can be changed and the process repeated.