Identification of Bacteria and Fungi in Various Types of Multi-Use Facilities in Bucheon, South Korea
Round 1
Reviewer 1 Report
The selected topic, the design and the methods are appropriate.
It is of concern that no explanation found for the presence of Bacillus anthracis in some samples, which is a higly dangerous pathogen, and such findings might be similar to the bioterror incidence 20 years ago in the USA. This issue could not be left without appropriate elucidation.
Author Response
Please see the attachment
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The paper illustrates an interesting approach and uses robust techniques. I think the scientific part of the paper is reasonable and makes this manuscript interesting. However, there are certain areas where some concerns need to be addressed. The authors should consider the below issues for the betterment of the work.
1. A concise and informative introduction is suggested to the authors rather current introductory write-up.
2. In the case of Discussion, I recommend elaborating the discussion in the revised manuscript focusing on the implications of these findings going to the publication of this manuscript in the Journal.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 3 Report
The manuscript presents an interesting piece of work on identifying buildings with higher potential for bioaerosol issues, and sampling to identify some of the species and airborne concentrations. The literature in this field is still evolving, and any additional good data is a useful contribution to the topic. In general this manuscript seems to be of good quality and interest, however there are a few areas that should be revised or addressed to further improve its potential impact. These are listed below in no particular order:
Title: not all species identified in the sampling would be considered "infectious" in a medical sense, in my opinion. I think this word should be deleted from the title.
Introduction, line 36: can some examples of what are considered "multi-use facilities" be provided? The interpretation of this may depend on the reader to some extent.
Line 40: "fine dust" - is this to mean fine particulate, or PM2.5?
Line 43 etc: airborne bacteria as a source of infectious disease is discussed, but generally in public environments viral respiratory disease transmission is more significant and common. Some small mention of this may be useful, even if it is not the topic of the work.
Line 48: "within 800 CFU/m3" should be "less than 800 CFU/m3" I believe?
Section 2.1: some some additional detail on the swab sampling method would be useful. How many swabs were done per sampling event at a location, and what area of surface was swabbed? Was only one spot swabbed? The number and extent of surfaces sampled can have a significant effect on the species collected and identified, so further information is needed to provide more context.
Line 99: how long was the sampling period at 100 L/min? Were there minimum and maximum allowable plate counts used to quantify the results?
Line 111: it is not clear how "airtightness" would be characterized for each facility. Was this based on qualitative survey answers, or some sort of physical measurements?
Line 181: some aspects of the selection criteria may require more discussion and justification. For example, it's not clear to me why "number of confirmed COVID-19 cases" would be a factor. It is quite different from the other factors, such as user density, ventilation, etc., and it is hard to see how it would be linked to bacteria and fungi concentrations. How was the number of cases attributed to a specific facility, since the transmission may have occurred elsewhere? A similar comment applies to the "fatality rate". Fatality due to what cause? Presumably fatalities would be quite rare in many of these facilities, which could skew the ranking in some way?
Table 2: it would be more consistent to use the same number format for the "mean total airborne bacteria" column, i.e. not the scientific notation currently used.
For Fig 3 and 4, the y-axes should have labels for better clarity. The decimal place in the y-axis numbers is not really necessary and makes it harder to read at first glance.
Section 3.2.2: these species identifications are interesting, but for better impact and meaning the authors should compare and contrast their results with others in literature for offices, schools, and other similar building environments.
General Discussion and Conclusions:
Some discussion of the study limitations should be added. For example, there is no direct way to link the CFU/m3 numbers to the species identified by 16S rna analysis. The collision sampling and culturing will only detect culturable/viable bacteria, whereas the 16S method is more inclusive of all species including non-culturable ones. It also cannot easily determine the actual numbers of each, only relative abundance, so it would be difficult to draw links between CFU counts and identifications.
There is also the issue that air sampling and surface swab analysis are addressing two different portions of the environment. These may or may not be directly related, as surface samples only collect those particulates or aerosols that have settled in that specific location.
It is also useful to reflect on the sources of the identified species. Are these sources within the buildings, or the local environment and brought in by air exchanges, or are they from humans shedding them from skin and clothing or other materials brought into the building? The sources may be quite different depending on the building and its uses.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
No further comments
