Thesis
Respirator and face mask filtration efficiency enhancement due to unipolar ion emission
University of Iowa
Master of Science (MS), University of Iowa
Summer 2023
DOI: 10.25820/etd.006864
Abstract
The filtration capabilities of surgical face masks and respirators are crucial in preventing the transmission of airborne pathogens and particles in healthcare settings as well to the general public. Previous studies have shown that the filtration efficiency of face masks can be influenced by various factors, such as the size and composition of aerosols. However, the potential enhancement in filter efficiency through the addition of ions remains largely unexplored. The main goal of the study was to investigate whether the addition of ions to an atmosphere containing aerosols increases filter efficiency of surgical facemasks and N95 respirators. The primary objective was to demonstrate whether aerosol ionization enhancement in surgical face masks results in successfully meeting National Institute of Occupational Safety and Health (NIOSH) standards for the particulate filtration efficiency of N95 respirators.
The experimental design involved the comparison of two ASTM-rated face masks, differing in filtration efficiency, with an N95 respirator, where the criteria of success was to investigate whether ionization enhancement increases filter capture efficiency, and a “quality factor” that combines the effect of both filter efficiency and flow resistance. Air ionization was observed with a small, portable air ionizer. An aerosol particle counter was used to collect ambient (upstream) and respirator (downstream) particulate counts in the size range of 0 to 380 nm to determine filter efficiency. A scanning mobility particle sizer was used to measure the overall capture efficiency of the masks in the fine and ultrafine range of particle size range where filter capture efficiency is typically poorest. Pressure drop was measured by using a calibrated pressure voltage reader.
When comparing efficiency and pressure drop by flow rate and ionizer status, each facepiece achieved a greater capture efficiency with the use of an ionizer with an increase from 79% to 94% at a low flow and from 79% to 91% at a high flow for the ASTM Level 1 face masks, and an increase from 87% to 98% for low flow and from 88% to 97% at a high flow for the ASTM Level 2 face masks . The quality factor also increased with the addition of the ionizer for each mask, according to data collected for pressure drop and penetration of each facepiece. Particle size capture efficiency testing demonstrated that particle capture efficiency increased as a result of addition of the ionizer. Increased quality of breathing as a result of increased filtration and capture efficiency from ionization demonstrates a protective method to enhance filtration of particulate aerosol for all FFR respirators and face masks.
Details
- Title: Subtitle
- Respirator and face mask filtration efficiency enhancement due to unipolar ion emission
- Creators
- Christian Feye
- Contributors
- Patrick T O'Shaughnessy (Advisor)T. Renée Anthony (Committee Member)Thomas M. Peters (Committee Member)
- Resource Type
- Thesis
- Degree Awarded
- Master of Science (MS), University of Iowa
- Degree in
- Occupational and Environmental Health
- Date degree season
- Summer 2023
- Publisher
- University of Iowa
- DOI
- 10.25820/etd.006864
- Number of pages
- xi, 83 pages
- Copyright
- Copyright 2023 Christian Feye
- Language
- English
- Date submitted
- 07/25/2023
- Description illustrations
- color illustrations
- Description bibliographic
- Includes bibliographical references (pages 75-83).
- Public Abstract (ETD)
The aim of this study was to investigate whether adding ions to an atmosphere containing aerosols increases the filter efficiency of surgical face masks and N95 respirators. By enhancing aerosol ionization in surgical face masks, the aim was to demonstrate that the National Institute of Occupational Safety and Health (NIOSH) standards for particulate filtration efficiency of N95 approved respirators could be successfully met.
To achieve this, two ASTM-rated face masks of different rated filtration efficiencies were compared to an N95 respirator. The criteria for success were to prove that ionization enhancement on an aerosol increases overall efficiency and "quality factor" which was affected by both filter efficiency and breathability through a face mask or respirator. A small, portable air purifier ionized the air for this experiment.
The research methods included using an aerosol particle counter to collect ambient and penetrating particulate counts inside a mask or respirator to determine the filter efficiency, and using an aerosol particle sizer and counter to measure the sizes of particles that penetrate or are captured by the filter in a face mask or respirator. Breathability was measured using pressure drop.
This study found that each mask increased in particle filtration efficiency and quality factor with the addition of the ionizer. An ASTM Level 1 mask reached greater than 90% filter efficiency, an ASTM Level 2 mask reached greater than 95% filter efficiency, and an N95 respirator reached nearly 99% efficiency at low and high simulated breathing flow rates. Particle size capture efficiency testing proved that particle capture efficiency increased as a result of the addition of the ionizer for all sized particles. Overall, the increased filtration and capture efficiency resulting from ionization demonstrates a protective method for enhancing filtration of particulate aerosol for all respirators and face masks. This can lead to an improved quality of breathing for individuals using such masks and respirators.
- Academic Unit
- Occupational and Environmental Health
- Record Identifier
- 9984454433802771
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