Accession Number:

AD0684101

Title:

EFFECT ON AIRBORNE BACTERIA OF EXTRANEOUS PARTICULATE MATTER OR AIR FILTRATION,

Descriptive Note:

Corporate Author:

NAVAL DENTAL SCHOOL BETHESDA MD

Report Date:

1969-01-07

Pagination or Media Count:

12.0

Abstract:

Dissemination of microorganism-bearing aerosols in dental operatories has raised questions about potential risks of airborne infection. The purpose of this study was to evaluate methods of reducing microbial concentrations in such aerosols. Measurements were made of the influence of particulate matter on airborne bacteria and the effectiveness of an 800-cfm high-efficiency particulate air HEPA filter unit in reducing airborne bacteria. A room, approximately 700 ft3 in size, was constructed of plastic material, and was kept sealed except for an intake of dust-free, bacteria-free air. The fallout rate of Bacillus subtilis spores was determined in a dust-free environment and also in the presence of known amounts of airborne particulate matter 3.0 to 15.0 gm of Ca3PO42 powder, or 0.3- or 1.0-gm of hair spray. The fallout rate of the spores 32 percent per hour was found to increase with the addition of either form of particulate matter, resulting in a maximum 2-fold increase with 5 gm of powder, and a 1.6-fold increase with 1 gm of spray. The HEPA filter unit was effective in reducing peak concentrations of airborne bacteria by 35 percent, and in clearing the room of all airborne spores in 8-10 minutes. Author

Subject Categories:

  • Medicine and Medical Research

Distribution Statement:

APPROVED FOR PUBLIC RELEASE