PONE-D-20-25645

Comparing the Fit N95, KN95, Surgical, and Cloth Face Masks & Assessing the Accuracy of Fit Checking

PLOS ONE

Dear Dr. O'Kelly,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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We look forward to receiving your revised manuscript.

Kind regards,

Amitava Mukherjee, ME, Ph.D.

Academic Editor

PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Partly

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: No

Reviewer #3: No

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: No

Reviewer #2: Yes

Reviewer #3: No

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: This paper evaluates the level of fit offered by various types of masks, and most importantly, assess the accuracy of implementing fit checks by comparing fit check results to quantitative fit testing results. This work seems interesting, however there are some remarks and comments which improve the present quality of the paper.

Introduction: Please improve the state of art using more scientific papers. Honestly, the authors reviewed the recent articles in this subject but more attention to the scientific paper could improve the introduction parts.

Materials and methods: This section is not clear for readers. Please provide more comprehensive way to express the Fit method. For example, using a schematic. Moreover, why did you use this method? Why not other methods? Also, the structure of this section should be modified.

Results and discussion: Please improve the quality of the figures. In my opinion it is better to combine results and discussion sections. What do the authors think about the relation between diffusion phenomenon and Fit testing?

Reviewer #2: This manuscript introduced the fitting tests of N95, KN95, surgical and cloth face masks, and compared the fit check results to quantitative fit testing results, emphasizing the importance of fitting of face coverings. This study is related to the current situation of COVID-19, and provided important information on the proper usage and evaluation of respirators and face masks. However, a few important aspects regarding the testing of the fitting and data analysis still need further clarification. The reviewer, therefore, recommends a major revision of this manuscript.

General comments:

1. A schematic diagram of the experimental setup is needed to show how the measurement of fit score was conducted. Including photos of the masks will also be very helpful. It was mentioned that two KN95 respirators and a selection of fabric face coverings were tested, but only one set of results for each were provided. Moreover, which N95 mask is the “Xiantao Zong” mask? It was not listed in Table 1.

2. Proper sealing of the respirators requires that should be no facial hair between the mask and face. However, as mentioned in the “Strength and Limitations” section, “M-51 and M-29 had some degree of facial stubble or hair.” It is, therefore, not clear on the purpose of evaluating the fitting of respirators with these two participants.

3. The author introduced a fit check according to the UK National Health Service (NHS) guidelines and the details of choosing seven participants. Although it can cover all the range, as the author stressed that this study quantified the fitting test results, the number of samples (participants) is indeed not sufficient to reflect such efforts. Also, there are more subjective results due to limited participants, even if it represented a range of age and prior experience. It appears in Fig. 2 that M-74 and F-28 operated the respirators and face masks with higher filtration efficiencies. Are the deviations in mask filtration largely dependent on the skills of the participants in using the masks? Including more participants in the study would improve the results of this study.

4. It was mentioned that several N95 and the KN95 did not fit the participants because of loose fits. Was it because of the straps or the respirator itself? Were the straps adjustable? Agan, including photos of the masks and identifying the locations of leakage would be very helpful.

Specific comments:

1. “Fit factor” or “fit score”? Please consider unifying these terms.

2. Page 5, masks tested section, last paragraph: “N95 and KN95 masks were worn for at least five minutes before testing to purge interior particles. Surgical masks and fabric face coverings, which were non-sealing, were worn for at least three minutes before testing.” What is the reason for choosing 3 mins and 5 mins each? Can the author explain this or relevant references?

3. Page 6, quantitative fit testing section, second paragraph: it should be quantitative fit testing, not qualitative fit testing, in “Qualitative fit testing was performed with…”

4. Regarding the fit factor, how to measure mask particle concentration (Cr)? Please clarify this equation and the value of 100 and 200. In addition, please specify the experiment conditions of fit tests.

5. Why are the fit check results for surgical mask and fabric face mask not shown?

6. If the authors are confident that the test of M-74 in Fig. 1 is an outlier, please remove the data and provide justification in the discussion. Otherwise, it will be misleading if readers directly refer to the figure.

7. Page 5: “Participants were asked to don the mask…” –> “… do to mask…”?

8. Page 9, fit checks section, second paragraph: “Out of 35 tests on N95 masks, participants believed 17 masks fit, 2 with low confidence, 7 with medium confidence, and 7 with high confidence.” The total number does not match 17.

Reviewer #3: The authors studied the fit and filtration efficiency of masks and respirators. As written, the text contributes very little to the current understanding of respirators. The conclusion that, “Some respirators don’t fit” is not very helpful.

1. What is the reproducibility within one subject? That is, have them put it on and off.

2. Different races and ethnicities have different face shapes. Could this be impacting the fit?

3. How does fit change over time? Or with decontamination?

4. Qualitative fit testing can use odorants.

5. A positive control with a 3M 6200 respirator, i.e., painters respirator, might be helpful.

6. The figures are very blurry. Not publishable in current state.

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Reviewer #1: No

Reviewer #2: No

Reviewer #3: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

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PONE-D-20-25645R1

Comparing the Fit N95, KN95, Surgical, and Cloth Face Masks & Assessing the Accuracy of Fit Checking

PLOS ONE

Dear Dr. O'Kelly,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Jan 07 2021 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

We look forward to receiving your revised manuscript.

Kind regards,

Amitava Mukherjee, ME, Ph.D.

Academic Editor

PLOS ONE

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #4: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #4: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #4: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #4: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #4: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #4: General comments:

1. It is recommended to replace “N95 and KN95 masks” with “N95 and KN95 respirators” throughout the paper because masks are not designed for complete sealing.

Specific comments:

1. Page 4: the full name of CDC is the Centers for Disease Control and Prevention.

2. Page 12 and 17: it will be very helpful to illustrate the impact of minor facial differences on the fit of the respirators. It will be good to compare more fit factor scores on page 12, instead of qualitative comparison only. Also, please quantify the subcutaneous fat under the chin if possible. The authors may consider adding “bone structure and nose length and width” to page 17 as your examined factors.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #4: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Attachments

Attachment

Submitted filename: paper review_PLOS ONE_1121.pdf

Comparing the Fit N95, KN95, Surgical, and Cloth Face Masks & Assessing the Accuracy of Fit Checking

PONE-D-20-25645R2

Dear Dr. O'Kelly,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Kind regards,

Amitava Mukherjee, ME, Ph.D.

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments: