Assessing Worker and Pedestrian Exposure to Pollutant Emissions from Sidewalk Cleaning: A Comparative Analysis of Blowing and Jet Washing Techniques
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
In general, the article is written in a satisfactory way, the state-of-the-art is presented and supported by references.
Line 234, a reference to Table S4 appears, in the supplementary material appears an excel without a legend referring to this table. Or place this reference to the excel file in the word document (supplementary material). In line 388 the reference of Table S4 are missing.
The discussion and conclusion could be further developed, there is a lot of interesting data in the article.
This manuscript clearly falls within the scope of the Air and I recommend the publication with these suggestions.
Author Response
In general, the article is written in a satisfactory way, the state-of-the-art is presented and supported by references.
Line 234, a reference to Table S4 appears, in the supplementary material appears an excel without a legend referring to this table. Or place this reference to the excel file in the word document (supplementary material). In line 388 the reference of Table S4 are missing.
Answer: We apologize for the oversight. We have updated the supplementary material to include Table S4 in the main document at line 390. Additionally, we have renamed the Excel file as requested. Thank you for bringing this to our attention.
The discussion and conclusion could be further developed, there is a lot of interesting data in the article.
Answer: Thank you for your feedback. We appreciate your suggestion to further develop the discussion and conclusion sections. In response to your comment, we have expanded these sections to provide a more comprehensive analysis of the data and its implications.
This manuscript clearly falls within the scope of the Air and I recommend the publication with these suggestions.
Reviewer 2 Report
Comments and Suggestions for Authors
The article needs minor revision:
1) I suggest adding a photo of the sites and 2, it will help the readers to imagine the sampling areas.
2) Table 1: How do you explain such high results (40.7ug/m3), compared to other results
Author Response
The article needs minor revision:
1) I suggest adding a photo of the sites and 2, it will help the readers to imagine the sampling areas.
Answer: Thank you for the suggestion. We have incorporated photos depicting the sampling sites into the manuscript Figure 1b and 1c. We hope these images will provide readers with a clearer understanding of the sampling areas and the techniques used.
2) Table 1: How do you explain such high results (40.7ug/m3), compared to other results
Answer: Thank you for your comment. The unusually high concentration observed at site 2 during winter (40.7 ug/m3) can be attributed to specific meteorological conditions, particularly intermittent wind gusts, as indicated in Table S2. We have now included a mention of these conditions in the legend of Table1 to explain the difference between this result and the others collected.
Reviewer 3 Report
Comments and Suggestions for Authors
Review of Assessing Worker and Pedestrian Exposure to Pollutant Emissions from Sidewalk Cleaning.
This is an interesting and professional study that should be published after minor revision to address the points listed below.
1. In the abstract it says that pedestrian operators are exposed to metallic particles - Cu, Zn, Mn. Please add a bit more detail to say which metals were (perhaps surprisingly) not seen, and, which metals were/were not analysed.
2. I am an experienced native speaker of English, author, reviewer and so on, but I have never encountered the word 'flashing' (e.g. 'blowing or flashing') as it is used in this manuscript and I am pretty sure it is a mistake that should be corrected. 'Flash' is to shine (light) briefly or make visible briefly. 'Flush' is A sudden flowing; a rush which fills or overflows, as of water for cleansing purposes. I have never considered these two words to be connected in the least bit, and the use of 'Flash', 'Flash cleaning' made me think that it was some kind of fast infrared heating or something, instead of a water jet. I strongly recommend removing use of 'flash' in the sense of using water and instead use flush or water jet or spray.
3. Line 149 etc. no need to have the multiplication dot in the units - a space implies multiplication.
4. Line 184 change 'blanc' to 'blank'
Great study, thank you, I enjoyed reading it. Very professional job of analysis and writing and excellent methodology.
Comments on the Quality of English Language
See comments in main review.
Author Response
Review of Assessing Worker and Pedestrian Exposure to Pollutant Emissions from Sidewalk Cleaning.
This is an interesting and professional study that should be published after minor revision to address the points listed below.
- In the abstract it says that pedestrian operators are exposed to metallic particles - Cu, Zn, Mn. Please add a bit more detail to say which metals were (perhaps surprisingly) not seen, and, which metals were/were not analysed.
Answer: Thank you for your feedback. We have revised the abstract to provide additional details on the metals analyzed and those that were not detected in our study.
- I am an experienced native speaker of English, author, reviewer and so on, but I have never encountered the word 'flashing' (e.g. 'blowing or flashing') as it is used in this manuscript and I am pretty sure it is a mistake that should be corrected. 'Flash' is to shine (light) briefly or make visible briefly. 'Flush' is A sudden flowing; a rush which fills or overflows, as of water for cleansing purposes. I have never considered these two words to be connected in the least bit, and the use of 'Flash', 'Flash cleaning' made me think that it was some kind of fast infrared heating or something, instead of a water jet. I strongly recommend removing use of 'flash' in the sense of using water and instead use flush or water jet or spray.
Answer: We apologize for the error. The term "Flash" has been replaced throughout the text with “jet washing” or "water jet", as recommended.
- Line 149 etc. no need to have the multiplication dot in the units - a space implies multiplication.
Answer: The modification has been made. Thank you for bringing it to our attention.
- Line 184 change 'blanc' to 'blank'
Answer: Done
Great study, thank you, I enjoyed reading it. Very professional job of analysis and writing and excellent methodology.
Answer: Thank you very much for your positive feedback! We're glad to hear that you enjoyed reading the study and found the analysis, writing, and methodology to be of high quality.
Reviewer 4 Report
Comments and Suggestions for Authors
This manuscript compares the effect of different sidewalk cleaning techniques on ambient concentrations of particulate matter, focusing on bioaerosols and metals and differentiating between occupational and passerby exposure. It provides a direct comparison of the degree of aerosolization during cleaning in different situations, information that can be used to adjust cleaning approaches and reduce exposure. Another strength of the paper is the focus on bioaerosols and metals in the near-road environment, which can also be used for comparison with similar measurements in other situations. The study is somewhat limited by relatively small sample size for the various combinations of factors – cleaning type, street type, season, operator/passerby, so careful interpretation of the results is needed. However, the reported concentrations are a useful benchmark for comparison with other studies.
In addition to these overall comments, I have several specific comments for the authors to consider:
- L35: Should this be “from” instead of “into”?
- L114: Should be “particulate matter” instead of “particles matter”.
- L119: Since you are talking about occupational exposure, it would be good to mention any personal protective equipment used by the operators in Section 2.3.
- L134-135: What was the duration of each cleaning activity? If there are important differences, a table would be helpful. For example, did site 1 take longer than site 2, or did blowing take less time than flashing? Either way, knowing the duration of exposure is important for considering potential health effects.
- L158-159: Some additional calibration is likely needed over the several months of this sampling campaign. Were any calibration checks done between sampling events, or at the end of sampling? Please describe the calibration and quality control activities in a bit more detail.
- L248-249: How long between cleanings at each site? Could this be part of the observed differences between site 1 and site 2?
- L251-252: Were these exposures measured on actual passersby and drivers, or at a representative location? How far away were the passersby from the cleaning activity?
- L263-264: Even though the levels of Cd and Pb were very low, it would be good to show the actual values, together with the respective LODs. This helps place the results in context with other near-road measurements. I suggest expanding Table 2 to include Cu, Cd, Pb, Zn, and Mn (or putting that table in the supplementary information).
- L290: I would say “blower operators” rather than “blowers”, and “were” instead of “where”.
- L314-317: Very good - this statement is helpful to put the study results in context.
- L326-327: This statement on the minor influence of the water jet on metal particle concentrations doesn’t seem to have clear support in the text or figures. This could be expanded upon in Table 2 and the surrounding text (see also the comment on L263-264).
- L356-358: This sentence is a little bit of overinterpretation and could be hedged a bit. First, the data from Table 3 don’t show a consistently large difference between water jet and electrical blower, although water jet does produce the lowest exposures. Also, the pathogenicity of the bioaerosols was not considered, so the degree of public health protection (as opposed to exposure reduction) is not clear.
- L364-365: This is an appropriate caveat.
- L375: When talking about occupational health risks, personal protective equipment (e.g., masks) should be mentioned.
Author Response
This manuscript compares the effect of different sidewalk cleaning techniques on ambient concentrations of particulate matter, focusing on bioaerosols and metals and differentiating between occupational and passerby exposure. It provides a direct comparison of the degree of aerosolization during cleaning in different situations, information that can be used to adjust cleaning approaches and reduce exposure. Another strength of the paper is the focus on bioaerosols and metals in the near-road environment, which can also be used for comparison with similar measurements in other situations. The study is somewhat limited by relatively small sample size for the various combinations of factors – cleaning type, street type, season, operator/passerby, so careful interpretation of the results is needed. However, the reported concentrations are a useful benchmark for comparison with other studies.
In addition to these overall comments, I have several specific comments for the authors to consider:
- L35: Should this be “from” instead of “into”?
Answer: Thank you for the suggestion. The modification has been implemented.
- L114: Should be “particulate matter” instead of “particles matter”.
Answer: Thank you for the suggestion. The modification has been implemented.
- L119: Since you are talking about occupational exposure, it would be good to mention any personal protective equipment used by the operators in Section 2.3.
Answer: This information was added in lines 150 and discussed in the current version of the manuscript.
What was the duration of each cleaning activity? If there are important differences, a table would be helpful. For example, did site 1 take longer than site 2, or did blowing take less time than flashing? Either way, knowing the duration of exposure is important for considering potential health effects.
Answer: The sampling time is provided in the Table S3 of the Supplementary methods and mentioned of the main text lines 161-163.
- L158-159: Some additional calibration is likely needed over the several months of this sampling campaign. Were any calibration checks done between sampling events, or at the end of sampling? Please describe the calibration and quality control activities in a bit more detail.
Answer: We are grateful to the reviewer for bringing to our attention the omission of this information. The relevant details have now been included in lines 172-176.
- L248-249: How long between cleanings at each site? Could this be part of the observed differences between site 1 and site 2
Answer: We appreciate your feedback. We do agree that the information provided in the previous version of the manuscript was not sufficiently detailed. To ensure consistency in the meteorological conditions for comparison, the two sites were sampled on the same day. This information has been added to lines 134-135 in the Materials and Methods section of the manuscript.
- L251-252: Were these exposures measured on actual passersby and drivers, or at a representative location? How far away were the passersby from the cleaning activity?
Answer: Personal air sampling for bioaerosols characterization was conducted on blower operators, drivers and pedestrians who were not involved in the cleaning process (scientific collaborators of the project who participated in data collection). Pedestrians were either following or preceding the blower operators during their activity at distances ranging from 5 to 10 meters. Furthermore, stationary sampling of bioaerosols was conducted at a distance of 2 meters behind the blower operator during blowing or jet washing to document the punctual exposure of passersby. We add these information lines 146-156 to clarify these different aspects in the material and methods and we have avoided the usage of the word “pedestrian” for blower operators to avoid any potential confusion.
- L263-264: Even though the levels of Cd and Pb were very low, it would be good to show the actual values, together with the respective LODs. This helps place the results in context with other near-road measurements. I suggest expanding Table 2 to include Cu, Cd, Pb, Zn, and Mn (or putting that table in the supplementary information).
Answer: The Table 2 was modified in accordance with the suggested modifications.
- L290: I would say “blower operators” rather than “blowers”, and “were” instead of “where”.
Answer: The modification was done.
- L314-317: Very good - this statement is helpful to put the study results in context.
Answer: Thank you for acknowledging this point.
- L326-327: This statement on the minor influence of the water jet on metal particle concentrations doesn’t seem to have clear support in the text or figures. This could be expanded upon in Table 2 and the surrounding text (see also the comment on L263-264).
Answer: We acknowledge that the sentence in the discussion section was overly broad and lacked support from our data. Consequently, we have revised this portion of the discussion to accurately reflect our findings
- L356-358: This sentence is a little bit of overinterpretation and could be hedged a bit. First, the data from Table 3 don’t show a consistently large difference between water jet and electrical blower, although water jet does produce the lowest exposures. Also, the pathogenicity of the bioaerosols was not considered, so the degree of public health protection (as opposed to exposure reduction) is not clear.
Answer: We agree with the reviewer's assessment. The discussion was revised to align more closely with the findings of the current study.
- L364-365: This is an appropriate caveat.
Answer: Thank you for acknowledging this point.
- L375: When talking about occupational health risks, personal protective equipment (e.g., masks) should be mentioned.
Answer: We thank the reviewer for pointing out this aspect. We have addressed this issue in the revised manuscript
