REDUCTION OF MICROBIAL CONCENTRATION IN AIR OF DENTAL OPERATING ROOMS BY HEPA FILTRATION
NAVAL DENTAL SCHOOL BETHESDA MD
Pagination or Media Count:
Microbial aerosols are known to be created and disseminated in dental operating rooms DORs in quantities sufficient to raise the possibility of cross infection. The purpose of this study was to evaluate the effectiveness of high efficiency particulate air HEPA filters in reducing the concentration of air-borne microorganisms. Test were made in DORs of 1600-, 1800-, and 3240-cu ft capacity with an 800-cfm HEPA filter unit. Concentrations of microorganisms were measured 4 times daily at approximately 2- to 3-hour intervals. Samples were taken in each DOR with 1-hour Reyniers air samplers drawing 1 cfm for 2 weeks without air filtration and then for 2 weeks with air filtration. In a DOR used for routine scaling with an ultrasonic instrument, the mean microbial air count of 21 viable particles VPcu ft without air filtration was reduced 90 percent when the air was filtered. In this DOR, peak recoveries of 185 VPcu ft without air filtration were reduced 84 percent when the air was filtered. Bacteria recovered during peak periods were predominantly alpha-hemolytic streptococci of the viridans group. In two DORs used only for routine operative dentistry, microbial air counts were lower, with mean values of 3-8 VPcu ft and peak values of 8-26 VPcu ft without air filtration. These concentrations were reduced 65 percent when the air was filtered. It was concluded that under normal working conditions an 800-cfm HEPA filter unit is effective in reducing the concentration of airborne microorganisms in a DOR by about 70 percent.
- Medicine and Medical Research