ELECTROSTATIC PRECIPITATION VS. HEPA FILTRATION IN REDUCTION OF AIRBORNE MICROORGANISMS IN DENTAL OPERATING ROOMS

The purpose of this study was to measure the ability of electrostatic precipitation ESP to reduce the number of airborne microorganisms in two DORs of 1,800 and 850 cu ft size, and to compare the results with those obtained with a high efficiency particulate air HEPA filter module. The effect of air cleaning by either one or two ESP units AIR FLOW RATE OF 175 CFM EACH or a floor model HEPA module 800 cfm was studied. The effectiveness of the units was tested using a Reyniers slit sampler to measure the reduction of microbial air concentrations. The reduction in number of microorganisms in the air of empty DORs was found to be influence by the ratio of room size to unit capacity. At a ratio of 21 the air cleaning effectiveness of the ESP and HEPA filter units was the same. A mean concentration of 5.0 VPcu ft was significantly reduced to 1.0 to 2.0 VPcu ft by either the ESP or the HEPA filter units. Peak microbial air concentrations in DORs where dental procedures were being performed were reduced by air cleaners at a higher rate than that found with no cleaners.