Reliability of Lower-Cost Sensors in the Analysis of Indoor Air Quality on Board Ships

Round 1

Reviewer 1 Report

Please see the attached file.

Comments for author File: Comments.pdf

Author Response

You can find our replies on the comments in the document in attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

In the manuscript atmosphere-1922124 describes the results of a study in which the authors carried out measurements of airborne pollutants in different indoor environments of a ship, using at the same time reference-grade instruments and "lower cost" instruments. The results obtained with the different techniques were then compared.

 

Overall, the manuscript should be improved in terms of with clarity of exposure and exhaustiveness. The introduction and results sections need to be consolidated. Some methodological doubts have been raised in the following comments, which I ask the authors to clarify. This could have a not negligible impact on the results obtained.

I report below a couple of comments that I ask you to consider

1.     Line 25: “older ship”: older than what? What are the characteristics of this ship, anyway?

2.     Line 19-23. The objective and design of the study do not emerge clearly from these sentences. If I understand correctly, monitoring was conducted using in the same scenario "reference-grade" instruments and alternative instruments (low-cost, portable, etc. This should be specified well, while now the generic term "sensor boxes" is indicated). The results of this comparison were then discussed. Please re-phrase to improve the clarity of these concepts.

3.     Line 32. I would recommend using a more generic term than "domestic activities" such as "occupants' activity" as the problem may concern not only the domestic environment but also other non-industrial living or working environments (offices, schools, public buildings etc. )

4.     Line 33-34. Perhaps this sentence needs to be rewritten for clarity. To be precise, indoor air quality is determined both by internal sources and by external sources (infiltration).

5.     Line 34-35: would it be possible to cite more references from bibliography, and more recent ones?

6.     Line 35-36. I would also recommend mentioning here a concept that is suggested later, namely that the theme of IAQ on ships presents substantial differences compared to what is expected for IAQ in buildings.

7.     Line 36-37.  Perhaps there can be an analogy (for some aspects) with the concentrations of in-cabin pollutants studied in cars and other means of road transport, for which there is a good body of literature?

8.     Line 50-67. I agree with what has been said here and I understood its meaning, also to motivate the use of low-cost and miniaturized sensors. However, it could also refer to the ISO 16000 standards series, that mentions a series of portable samplers and instruments usually worn by people during indoor activities to monitor their personal exposure, even though no guidelines are clearly specified for these kinds of devices. the issue of using miniaturized / low cost sensors for IAQ assessment instead of reference grade tools has already been discussed quite extensively, anyway (see for example Spinazzè et al., Applied Spectroscopy Reviews, DOI: 10.1080/05704928.2021.1995405; Ródenas García, et al. Applied Spectroscopy Reviews, DOI: 10.1080/05704928.2022.2085734; Kang et al., Sci Total Environ. 2022, 818, 151769. doi:10.1016/j.scitotenv.2021. 151769)

9.     Line 89-92: There are also studies that highlight what the advantageous implications of these technologies can be. For example, to name just one Howard, et al. Am. J. Ind. Med. 2022, 65, 3-11

10.  Line 139-140. What do the authors mean with “dare are cleaned and quantified”?

11.  In general (in the title already, but also throughout the manuscript) the concept of “lower-cost sensors”, should be defined. Lower than what? I am more familiar with the terminology of "low-cost" sensor, which however is a generic term and should be defined (see Fanti et al. Sensors 2021, 21, 4513. https://doi.org/10.3390/s21134513 , And Howard et al. Am. J. Ind. Med. 2022, 65, 3-11)

12.  Number and duration of the measurement sessions, as well as the number and consistency of the data obtained should be better specified.

13.  Line 125-173. If I understand correctly, a low-cost sensor and a corresponding reference-grade instrument were not used for all the pollutants investigated (for VOCs for example). For what reason? In this case, then, what evaluation was carried out? A summary table of the techniques used and compared and the type of evaluation performed could be useful.

14.  Figure 1 is not very immediate to understand. First of all, the value of the ordinate scales are different for each pair of graph, and this makes the comparison unintuitive. I suggest plotting the data obtained with reference-grade instruments and the corresponding low-cost sensors on the same graph, to facilitate comparison. Furthermore, the temporal trend already provides a good indication for a direct comparison between the two data series but also other types of graphs (scatter plots, bland-altman plots) can provide more precise information on the comparison between two data series, obtaining also quantitative information on the relative performance of the compared instruments.

15.  Line 175-214. The discussion is correct, but it essentially remains on an interlocutory and qualitative level. There are quantitative methods for this type of evaluation. See for example Kang et al. Science of the Total Environment 818 (2022) 151769 for information in this regard. The same applies to the discussion on PM measures (from line 277 onwards)

16.  I understood the meaning of "Invisible nanoparticles" but the term seems misleading to me. Perhaps it would be better to refer to the sensitivity of the instrument or to the instrumental limit imposed by the technique.

 

17.  As explained in the previous points, the results section may require substantial changes or, rather, the discussion of the obtained results should be broadened and improved. This could have an impact on the conclusions, which should be revised accordingly.

Author Response

You can find our replies on the comments in the file in attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors have addressed my comments adequately. The second sentence in section 2.3 "... and sometimes even why" reads a little awkward. Otherwise, I have no further comments. 

Reviewer 2 Report

The authors replied duly and completely to all the submitted comments and clarified the doubts posed by the reviewers. I have no further comments to submit.