Evaluation of the Cooling Effect of an Outdoor Misting Fan for Workers in Hot Environments Wearing Personal Protective Equipment (PPE)
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe author has picked very important topic regarding PPE. Mist fan evaporative cooling can be very good solution to this problem. Author has explained theoretically as well as experimentally this research study. Introduction includes detailed literature review also. I liked the way how author has analyzed the convection heat transfer and body skin temperature in whole manuscript. Overall, this manuscript is well written and can be accepted as it is.
Author Response
Comment 1: The author has picked very important topic regarding PPE. Mist fan evaporative cooling can be very good solution to this problem. Author has explained theoretically as well as experimentally this research study. Introduction includes detailed literature review also. I liked the way how author has analyzed the convection heat transfer and body skin temperature in whole manuscript. Overall, this manuscript is well written and can be accepted as it is.
Response 1: Thank you for your evaluation and approval.
For your information, we will be making some small edits of minor grammar mistakes, adding more to the literature review, and removing some of the more basic parts of the theory/equations based on some ideas from other reviewers.
Reviewer 2 Report
Comments and Suggestions for AuthorsThis study is important and necessary, before publication, some modifications should be needed.
1. In introduction part, the discussion of the research background is too short, And authors should add the description of the research importance. That’s very important.
2. In section 2.1, it seemed that the description of the different theory is too long, too tedious, just the words, if authors have modified the equations. That’s necessary. If not ,please reduce the waste descriptions.
3. In section 3, please add the figures of your experiment, we should know your experiment design.
4. All the references are used in Roman numbers, this is not convenient, please choose the ordinary Arab numbers.
In conclusion, this study is important and very necessary, after modifying the mentioned questions. It can be published.
Comments on the Quality of English Language
Minor improvements
Author Response
Comment 1.
In introduction part, the discussion of the research background is too short, And authors should add the description of the research importance. That’s very important.
Response 1.
Thanks for this point. We have added much more background about recent developments in worker cooling and personal cooling as well as surveys of adverse effects of PPE. With additions and edits, we created section 1.2 “Relevance and potential of the research.”
Comment 2.
In section 2.1, it seemed that the description of the different theory is too long, too tedious, just the words, if authors have modified the equations. That’s necessary. If not ,please reduce the waste descriptions.
Response 2
Agreed that our explanation of all the equations is far too long. We have removed many of the more basic parts that are common knowledge in the field, limiting mainly to the equations we actually used in our analysis.
Comment 3.
In section 3, please add the figures of your experiment, we should know your experiment design.
Response 3.
We have added photos of the main components of the measurement device Fig 3, the experiment site, and the apparatus during experiment Fig 6 a and b.
Comment 4.
All the references are used in Roman numbers, this is not convenient, please choose the ordinary Arab numbers.
Response 4.
We have corrected all references to use the journal format.
Comment 5
In conclusion, this study is important and very necessary, after modifying the mentioned questions. It can be published.
Response 5
Thank you for your constructive comments and understanding.
Reviewer 3 Report
Comments and Suggestions for Authors1. There is no uniformity in the font of references;
2. The table does not use the format of a three-line table;
3. Because sweat evaporation should be different from water evaporation, can water-soaked clothes really simulate sweating? What standards are used to determine the humidity of clothing?
4. Provide a more detailed exploration of existing techniques and methods used in similar environments to highlight the novelty of your work;
5. Why is 34°C used as the initial skin temperature?
6. Is it possible to present some pictures of the experimental site and the spray fan to make it easier for readers to understand the article?
7. Whether the mannequin can be presented in the form of a picture is very unintuitive, which makes it difficult for readers to imagine the model.
Comments on the Quality of English Language
Minor editing of English language required.
Author Response
Comment 1.
There is no uniformity in the font of references;
Response 1:
Apologies for this. The references are now formatted correctly.
Comment 2.
The table does not use the format of a three-line table;
Response 2.
Apologies for this. Tables are fixed.
Comment 3.
Because sweat evaporation should be different from water evaporation, can water-soaked clothes really simulate sweating? What standards are used to determine the humidity of clothing?
Response 3:
Good point. Tap water used to wet the clothes will likely yield the highest evaporation cooling simulation of sweating effects, with no reduction in evaporation due to salt and salt buildup on the skin and clothes. One of the initial investigations on this effect by Berglund (1973) showed the vapor pressure reduction would be up to about 25% lower than pure water. Examination of the effect of salt concentration would add another parameter to the experiment, thus increase the number of trials necessary for statistically significant results, plus time and effort to set up each trial (including washing and drying clothes each day), so it was not done for this case, but it is definitely an important point for investigation.
We added the above explanation of this point into Section 3.7.2
We do plan to do much more detailed experiments next summer with just 1 or 2 warmed cells, rather than a full mannequin, in a rig similar to the standard used to measure thermal resistance of clothing spelled out in ISO 11092 but adding more sensors to measure temperature, vapor pressure and heat flux between all layers of clothing. The simpler rig will allow much faster experiment turnaround time, thus much greater number of trials to investigate more experiment parameters in more detail. We will include realistic salt-water “sweat”, wind speed, various clothing layers, and more accurate measurement of the wetting due to mist on the outer layer. We are already examining the wetting pattern of mist onto clothes by microscope, with interesting initial results showing it is quite complex.
Comment 4.
Provide a more detailed exploration of existing techniques and methods used in similar environments to highlight the novelty of your work;
Response 4:
We are adding much more background about recent developments in personal cooling systems to better show the relevance and problems faced, as well as more background about common techniques for thermal mannequins.
A search specifically for use of mist cooling with PPE yielded few results other than our own conference papers done as progress reports of the research in 2022 and 2023.
Added information from these sources:
Martinez-Albert M, Díaz-García P, Bou-Belda E. Development of a new testing protocol to evaluate cooling systems. EXCLI J. 2023 Jul 6;22:583-594. doi: 10.17179/excli2023-6105.
National Institute for Occupational Safety and Health(NIOSH). PPE Heat Burden. https://www.cdc.gov/niosh/heat-stress/recommendations/ppe.html, (accessed 2024-12-20)
Comment 5.
Why is 34°C used as the initial skin temperature?
Response 5:
The neutral skin set point temperature in the ASHRAE 55 model is 33.7C. The ISO 7933 model algorithm designed for hot environments uses an initial skin temperature of 34.1C.
The ISO model predicts that skin temperature will be 34.16C after 1 hour of exposure to a hot environment at air temperature of 30C, MRT of 30C, rel. humidity 40%, standing (1 met) in practically still air (v = 0.1m/s) wearing long sleeve work clothes (0.85 clo).
Both the ASTM F1291-22 standard for a dry mannequin in a cool environment and the ASTM F2371-16 standard for a sweating mannequin in a hot environment calls for skin temperature 35C +/- 0.5C. According to Jette et al. typical set values are 34C or 35C depending on the lab.
The AIJ Environmental Standards call for calibrating thermal mannequin surface temperature sensors in a 34C environment.
Added to text:
The skin temperature is typically set at about 34°C or 35°C in thermal comfort models, and standards and practice of experiments with thermal mannequins.
Comment 6.
Is it possible to present some pictures of the experimental site and the spray fan to make it easier for readers to understand the article?
Response 6:
Yes. Thanks for asking about this. We have added photos of the main components of the measurement device Fig 4, the experiment site, and the apparatus during experiment Fig 7 a and b.
Comment 7.
Whether the mannequin can be presented in the form of a picture is very unintuitive, which makes it difficult for readers to imagine the model.
Response 7:
This is also in the photos we have added. We can add more photos and diagrams if needed. Not sure about size limits for the journal.
Reviewer 4 Report
Comments and Suggestions for AuthorsThe article presents an important issue of cooling at workstations in hot climates. The problem concerns the thermal quality of workers wearing Personal Protective Equipment. As a solution, the authors propose the use of mist fan evaporative cooling. The research tool was a thermal mannequin with heat flux sensors in 8 places on the body. The article raises an interesting issue and includes an in-depth analysis of the proposed methodology and solution. The authors analyzed many variants and configurations over a long period. While reading the article, several issues were noticed that should be considered to increase the quality of the publication.
A detailed analysis is presented below.
Abstract
The last sentence of the abstract is constructed incomprehensibly and should be rephrased. This is about a sentence: "Under international standards for workers in hot environments based on metabolic rate and WBGT(wet bulb globe temperature), such as ISO 7243, this equate to an average of about a 0.35ºC (dry clothes with PPE) to 0.61ºC (wet clothes with PPE) increase in acceptable WBGT. "
Introduction
The bibliography list contains a list of 39 publications, of which the introductory part includes references to only 16. For instance, publications 17-24 were mainly used to present the theory. Further citations are mainly guidelines and standards, and citations regarding the adopted methodology. In the reviewer's opinion, the authors should extend this chapter to include a discussion of a larger number of articles addressing this issue, e.g.:
1. Bongers, C.C.W.G.; de Korte, J.Q.; Zwartkruis, M.; Levels, K.; Kingma, B.R.M.; Eijsvogels, T.M.H. Heat Strain and Use of Heat Mitigation Strategies among COVID-19 Healthcare Workers Wearing Personal Protective Equipment—A Retrospective Study. Int. J. Environ. Res. Public Health 2022, 19, 1905. https://doi.org/10.3390/ijerph19031905
2. Haihua Jiang, Bin Cao, Yingxin Zhu, Improving thermal comfort of individual wearing medical protective clothing: Two personal cooling strategies integrated with the polymer water-absorbing resin material, Building and Environment 243, 2023. https://doi.org/10.1016/j.buildenv.2023.110730
3. Dąbrowska, A.; Kobus, M.; Sowiński, P.; Starzak, Ł.; Pękosławski, B. Integration of Active Clothing with a Personal Cooling System within the NGIoT Architecture for the Improved Comfort of Construction Workers. Appl. Sci. 2024, 14, 586. https://doi.org/10.3390/app14020586
4. Wen Yi, Yijie Zhao, Albert P.C. Chan, Edmond W.M. Lam, Optimal cooling intervention for construction workers in a hot and humid environment, Building and Environment 118, 2017, https://doi.org/10.1016/j.buildenv.2017.03.032
Chapter 1.1 containing the description of the experiment, as the name suggests, should be included in the Materials and Methods chapter, according to the template. Chapter 2 - Theory, on the other hand, could be a subchapter of the introduction chapter.
Experiment
The chapter describes in detail the measuring station, components, including the mannequin used, and the adopted methodology. The abbreviation RMSE (root mean square error) should be explained in line 337. The abbreviation "WC" (I assume it stands for "work clothes") used in Table 2 is not explained.
Results
The caption of Figure 9 should include an explanation of each of the graphs (it would be good to divide them into parts (a)-(h) with an explanation of which part of the body they refer to, as in the template). It refers also to Figure 10.
General remarks
Formatting and the editorial page require significant corrections. The page layout, the citation format, and the way of presenting tables and figures are inconsistent with the journal's requirements and the provided template.
The authors' note should not be placed at the beginning of the article but in the appropriate subsection at the end of the article.
The text contains numerous linguistic and grammatical errors and typos, for example:
- line 32: "...regions where is currently almost never occurs [i]."
- line 33 "Heat stress on can lead to heat-related illness..."
- line 535 "The 4 least statistically significant cases includes..."
In conclusion, the article is interesting and requires only minor changes to improve the quality of the entire publication and clarity for the reader. The reviewer has no comments on the substantive side, including the content regarding the methodology or the presented results. The authors presented the adopted methodology and the proposed solution in great detail. They analyzed the results in depth and correctly presented the obtained results. The main comment concerns the editorial side. Typos and language errors were noticed in the text. Additionally, the entire article does not meet the requirements of the journal regarding the layout, presentation of figures and tables, and the entire format. Before publication, it will be necessary to adjust the form and edit the text. However, this does not reduce the overall positive reception of the entire article.
Therefore, I recommend accepting the article after making any necessary corrections in accordance with the review.
Best regards.
Comments on the Quality of English LanguageTypos and language errors were noticed in the text as described in the review.
Author Response
Comment 1
Abstract
The last sentence of the abstract is constructed incomprehensibly and should be rephrased. This is about a sentence: "Under international standards for workers in hot environments based on metabolic rate and WBGT(wet bulb globe temperature), such as ISO 7243, this equate to an average of about a 0.35ºC (dry clothes with PPE) to 0.61ºC (wet clothes with PPE) increase in acceptable WBGT. "
Response 1:
Yes, looking with fresh eyes, that really is a jumble! Edited down to half the size and just the important point.
Edited version:
“Under the ISO 7243 international standard for workers in hot environments, this would increase the acceptable WBGT(wet bulb globe temperature) by over 0.6°C.”
Comment 2
Introduction
The bibliography list contains a list of 39 publications, of which the introductory part includes references to only 16. For instance, publications 17-24 were mainly used to present the theory. Further citations are mainly guidelines and standards, and citations regarding the adopted methodology. In the reviewer's opinion, the authors should extend this chapter to include a discussion of a larger number of articles addressing this issue, e.g.:
Response 2:
Agreed that our literature section is too short on background. Thank you for the references. The major relevant points from these sources and others found along the way are added. The case of using Peltier devices with clothing for personal cooling is especially interesting and opens up interesting possibilities. We have added several more sources about current issues and developments in worker cooling and personal cooling systems.
- Bongers, C.C.W.G.; de Korte, J.Q.; Zwartkruis, M.; Levels, K.; Kingma, B.R.M.; Eijsvogels, T.M.H. Heat Strain and Use of Heat Mitigation Strategies among COVID-19 Healthcare Workers Wearing Personal Protective Equipment—A Retrospective Study. Int. J. Environ. Res. Public Health 2022, 19, 1905. DOI:10.3390/ijerph19031905
This can have a negative impact beyond that on the workers themselves. Bongers et al. found that 19% of health workers surveyed during the initial year of the COVID-19 pandemic reported they had performed their medical duties less accurately while wearing PPE.
Cold drinks and longer breaks were used far more often than means that could be used while working (cooling vests or cold towels) both due to ease of availability and worker preference for the former.
- Haihua Jiang, Bin Cao, Yingxin Zhu, Improving thermal comfort of individual wearing medical protective clothing: Two personal cooling strategies integrated with the polymer water-absorbing resin material, Building and Environment 243, 2023. https://doi.org/10.1016/j.buildenv.2023.110730
Jiang et al developed a combination of water-absorbent hygroscopic material inner clothing and a condensation package for use under PPE, tested with human subjects in typical medical scrubs. The combination of both strategies yielded slight decreases in skin temperature over time compared to PPE without cooling, and improved thermal comfort votes to nearly the same as to wearing only surgical scrubs with no PPE. A limitation for future improvement being the usable time of the absorbent material before replacement, and the effect of heating generated by condensation.
Addition from CDC/NUSTL 2016
According to a survey by DHS of several manufacturers’ personal cooling systems PCM vests typically can be used for a period of about 2 hours, while longer periods of over 4 hours are possible at the cost of more weight (many over 3 kg)
National Urban Security Technology Laboratory. Personal Cooling Systems Market Survey Report. 2016. https://www.dhs.gov/sites/default/files/publications/PCS-MSR_0514-508.pdf (accessed 2024-12-20)
Addition from Lou 2022
Lou et al are developing a wearable cooling and dehumidifying system for use under PPE while still maintaining the PPE barrier by using a thermoelectric cooling unit attached to the lower back which can circulate cooled air through a vest and wick away moisture. The system can extract about 52W of heat for up to 6 hours at low weight of 1.2kg including battery, which is claimed as up to 5 times more effect per unit weight of the unit as compared to a common PCM or ice/liquid systems.
Lun Lou, Yiying Zhou, Yishu Yan, Yang Hong, Jintu Fan. Wearable cooling and dehumidifying system for personal protective equipment (PPE), Energy and Buildings 276,
2022, 112510. DOI: 10.1016/j.enbuild.2022.112510.
Addition from Delkumburewatte
Delkumburewatte and Dias developed a personal cooling pouch using thermoelectric cooling and circulation of R-134a refrigerant for fitting into clothing such as PPE. It effectively removed about 20W using a single unit of roughly 25cm X 20cm.
Delkumburewatte, G. B.; Dias, T. Wearable cooling system to manage heat in protective clothing. Journal of The Textile Institute, 2011, 103(5), 483–489. DOI:10.1080/00405000.2011.587647
- Dąbrowska, A.; Kobus, M.; Sowiński, P.; Starzak, Ł.; Pękosławski, B. Integration of Active Clothing with a Personal Cooling System within the NGIoT Architecture for the Improved Comfort of Construction Workers. Appl. Sci. 2024, 14, 586. https://doi.org/10.3390/app14020586
Flexible thermoelectric elements are being adapted for use in worker clothing. Dabrowska et al. fitted outdoor laborer safety clothing with such TE cooling and a dedicated electronic control system. Subjects at a high exertion level over an hour in a 23C indoor environment showed reduced skin temperature by up to 2.6C with average reduction of 1C below the initial state. The authors propose the system could be improved with AI training to create a personalized cooling system.
- Wen Yi, Yijie Zhao, Albert P.C. Chan, Edmond W.M. Lam, Optimal cooling intervention for construction workers in a hot and humid environment, Building and Environment 118, 2017, https://doi.org/10.1016/j.buildenv.2017.03.032
Yi et al. found that PCM cooling vests improved comfort and reduced skin temperature during heavy exertion in a hot summer environment, but did not alleviate heat strain or prolong work duration. However, their use after exertion speeded cardiovascular and thermal strain recovery.
Comment 3
Chapter 1.1 containing the description of the experiment, as the name suggests, should be included in the Materials and Methods chapter, according to the template. Chapter 2 - Theory, on the other hand, could be a subchapter of the introduction chapter.
Response 3:
Yes, that will definitely make the flow of the article much better. Thank you.
We have moved Chapter 1.1 into Chapter 3 and added more subchapters in Ch 3. The Theory section is kept in Ch 2, but shortened by removing the more basic elements which are already common knowledge in the field, focusing mainly on the equations actually used in the analysis here.
Comment 4.
Experiment
The chapter describes in detail the measuring station, components, including the mannequin used, and the adopted methodology. The abbreviation RMSE (root mean square deviation) should be explained in line 337. The abbreviation "WC" (I assume it stands for "work clothes") used in Table 2 is not explained.
Response 4:
Thank you for finding these omissions. Looking again, RMSE really should be “RMSD Root mean square difference” as it is not an error, but a difference.
These 2 items are fixed and we have checked the whole text again for similar omissions.
Comment 5.
Results
The caption of Figure 9 should include an explanation of each of the graphs (it would be good to divide them into parts (a)-(h) with an explanation of which part of the body they refer to, as in the template). It refers also to Figure 10.
Response 5:
Thank you for this point. We have adjusted all figures to match the template format.
Comment 6.
General remarks
Formatting and the editorial page require significant corrections. The page layout, the citation format, and the way of presenting tables and figures are inconsistent with the journal's requirements and the provided template.
The authors' note should not be placed at the beginning of the article but in the appropriate subsection at the end of the article.
The text contains numerous linguistic and grammatical errors and typos, for example:
- line 32: "...regions where is currently almost never occurs [i]."
- line 33 "Heat stress on can lead to heat-related illness..."
- line 535 "The 4 least statistically significant cases includes..."
Response 6:
Apologies for the poor formatting. The journal editors kindly helped to start to work the paper a bit more into the journal format and we made the rest of the adjustments. Looking at the paper with fresh eyes, the lines you kindly listed as well as few other points that were wrong or unclear have been corrected.
Comment 7.
In conclusion, the article is interesting and requires only minor changes to improve the quality of the entire publication and clarity for the reader. The reviewer has no comments on the substantive side, including the content regarding the methodology or the presented results. The authors presented the adopted methodology and the proposed solution in great detail. They analyzed the results in depth and correctly presented the obtained results. The main comment concerns the editorial side. Typos and language errors were noticed in the text. Additionally, the entire article does not meet the requirements of the journal regarding the layout, presentation of figures and tables, and the entire format. Before publication, it will be necessary to adjust the form and edit the text. However, this does not reduce the overall positive reception of the entire article.
Therefore, I recommend accepting the article after making any necessary corrections in accordance with the review.
Best regards.
Response 7:
Thank you for the very constructive comments and understanding.
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsAuthors have modified the quality of the manuscript
