Efficiency of Degraded Electret Filters: Part II – Field Testing Against Workplace Aerosols
Year: 2003
Type: article
Abstract: Field tests were conducted to measure the efficiency of N95, R and P95 and P100 filters from two manufacturers against workplace aerosols. Three groups of each type of filter were tested: 1) untreated; 2) irradiated with ionizing radiation; and 3) dipped in isopropanol for 15 seconds. The purpose of the irradiation and isopropanol treatments was to produce laboratory penetration values above those allowed for approval using NIOSH test conditions. Prior to exposure in the field, nearly all irradiated and isopropanol-dipped filters had laboratory penetration values higher than permitted for approval using NIOSH test conditions. The filters were exposed to either a grinding aerosol or an oil mist in a steel foundry. Results indicated that even filters with laboratory penetration values higher than permitted for NIOSH approval performed well under these field conditions. Only the isopropanol-dipped N95 filters from one manufacturer had mean field penetration greater than 1%. None of the R or P filters permitted detectable penetration of the oil mist. Some untreated and irradiated N95 filters from both manufacturers were also exposed to the oil mist. No detectable oil mist penetration was found. These results indicate that current NIOSH approved N, R and P series filters perform very well under workplace conditions. The worst-case conditions used in NIOSH testing provide a very large margin of safety in the event of exposure to degrading workplace conditions.
DOI: 10.66828/001c.167585
Authors: Larry L. Janssen*, Jeanne O. Bidwell, Haskell E. Mullins, Thomas J. Nelson
Institution: 3M (United States)
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W7203674152