A Miniaturized Electrostatic Precipitator Respirator Effectively Removes Ambient SARS-CoV-2 Bioaerosols

  1. Rachel K. Redmann
  2. Brandon J. Beddingfield
  3. Skye Spencer
  4. Nicole R. Chirichella
  5. Julian L. Henley
  6. Wes Hager
  7. Chad J. Roy

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Abstract

The inhalation of ambient SARS-CoV-2-containing bioaerosols leads to infection and pandemic airborne transmission in susceptible populations. Filter-based respirators effectively reduce exposure but complicate normal respiration through breathing zone pressure differentials; therefore, they are impractical for long-term use. Objectives: We tested the comparative effectiveness of a prototyped miniaturized electrostatic precipitator (mEP) on a filter-based respirator (N95) via the removal of viral bioaerosols from a simulated, inspired air stream. Methods: Each respirator was tested within a 16 L environmental chamber housed within a Class III biological safety cabinet within biosafety level 3 containment. SARS-CoV-2-containing bioaerosols were generated in the chamber, drawn by a vacuum through each respirator, and physical particle removal and viral genomic RNA were measured distal to the breathing zone of each device. Measurements and Main Results: The mEP respirator removed particles (96.5 ± 0.4%), approximating efficiencies of the N95 (96.9 ± 0.6%). The mEP respirator similarly decreased SARS-CoV-2 viral RNA (99.792%) when compared to N95 removal (99.942%), as a function of particle removal from the airstream distal to the breathing zone of each respirator. Conclusions: The mEP respirator approximated the performance of a filter-based N95 respirator for particle removal and viral RNA as a constituent of the SARS-CoV-2 bioaerosols generated for this evaluation. In practice, the mEP respirator could provide equivalent protection from ambient infectious bioaerosols as the N95 respirator without undue pressure drop to the wearer, thereby facilitating its long-term use in an unobstructed breathing configuration.

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  1. Version published to 10.3390/v14040765
  2. ScreenIT

    SciScore for 10.1101/2022.01.27.22269961: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Ethicsnot detected.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power AnalysisResults showed (Fig. 1d) that a ∼0.35 milliwatts (mw) power selection resulted in a particle collection of ∼95%.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Experimental Models: Cell Lines
    SentencesResources
    Individual all glass impingers (AGI-4, SKC, Eighty-four, PA) were used to collect aerosol sample from either the ambient chamber or the flow distal to each respirator and was actuated upon initiation of each run of the aerosol system.
    AGI-4
    suggested: None
    Positive controls consisted of SARS-CoV-2 infected VeroE6 cell lysate.
    VeroE6
    suggested: JCRB Cat# JCRB1819, RRID:CVCL_YQ49)
    Software and Algorithms
    SentencesResources
    Statistics: All data from the evaluation studies that included particle counting and viral bioaerosol removal was assessed using Prism 9 (GraphPad Software, San Diego, CA).
    GraphPad
    suggested: (GraphPad Prism, RRID:SCR_002798)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    4.1 Limitations: There are several limitations in the preliminary evaluation study performed on the mEP respirator as the generation of SARS-CoV-2 bioaerosols necessitated the use high containment (biosafety level 3) laboratory environment and unique aerobiology facilities configured for studies with high consequence pathogens and not necessarily respirator efficacy testing. The configuration conventionally used to test efficacy (NIOSH standard 42 CFR 84 also referred to as “ Part 84”) requires the use of high flow input (≈85 LPM) as inlet flow across the face of the filter substrate being tested for removal efficiency. The high flow simulates pressure drop associated with the velocity of inspiration experienced by the user when breathing through a filter-based respirator. The mEP respirator is configured whereas there is near inperceptable pressure drop upon inspiration, thus there is no utility for the use of high flows for the purposes of evaluation. Rather, the inlet flows used in this evaluation approached but did not exceed 6 LPM during the studies. The disparity between the flowrates used in the NIOSH testing and this evaluation can be considered a weakness of the study. Similarly, although the mEP and the N95 respirators were tested under the inspiration configuration (6 LPM either across the filter substrate of the N95 or through the inlet of the mEP), neither respirator was tested for efficacy for particle removal efficacy upon expiration. Although the mEP respirato...

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    Results from scite Reference Check: We found no unreliable references.

    About SciScore

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  3. Version published to 10.1101/2022.01.27.22269961v1 on medRxiv