Round 1

Reviewer 1 Report

1.     The author claimed that "The method of detection limit (MDL) for chemical species affects the results of risk assessment" and "Our study can be used to understand the effects of MDL on the health risk assessments of HAPs" in the Abstract. How does MDL affect risk assessment?

2.     "We determined the MDL for high levels of formaldehyde and acetaldehyde and observed a high fraction of health risk in the investigated area." Specific risk level, carcinogenic or non-carcinogenic needs to be stated in the Abstract.

3.     Introduction is too long. This section states a lot of well-known knowledge about VOCs. However, the significance of the study was not emphasized. The authors should summarize existing research results and clarify unresolved issues. What is the significance of this study? The relationship between the MDL for chemicals with risk assessment should be emphasized. Please rewrite this section.

4.     There is some redundancy in the Results and Discussion section, and there are too many segments that do not emphasize the key points. It is recommended to modify them.

5.     All data in the Results and Discussion section should be kept to two significant figures.

6.     The entire article is too long. It is recommended that some of the content in the Materials and Methods section, and some graphs and tables in the Results and Discussion section can be placed in the Supporting Materials.

Moderate editing of English language required.

Author Response

Reply to reviewers’ comments

 

Manuscript ID: atmosphere-2521882

 

Title: Effect of Method Detection Limit on Health Risk Assessment of Hazardous Air Pollutants in an Urban Industrial Complex Area

 

Reviewer 1

1. The author claimed that "The method of detection limit (MDL) for chemical species affects the results of risk assessment" and "Our study can be used to understand the effects of MDL on the health risk assessments of HAPs" in the Abstract. How does MDL affect risk assessment?

Response: Thank you for your comments. We have revised the abstract. If the ambient concentration is lower than MDL, the risk value cannot reflect the true condition of health risk. However, high MDL can lead the high risk. Therefore, the improvement of analysis methods and instruments is important to reduce MDL and achieve health risk assessment.

 

2. "We determined the MDL for high levels of formaldehyde and acetaldehyde and observed a high fraction of health risk in the investigated area." Specific risk level, carcinogenic or non-carcinogenic needs to be stated in the Abstract.

Response: Thank you for your comments. We have revised the abstract and made it clearer.

 

3. Introduction is too long. This section states a lot of well-known knowledge about VOCs. However, the significance of the study was not emphasized. The authors should summarize existing research results and clarify unresolved issues. What is the significance of this study? The relationship between the MDL for chemicals with risk assessment should be emphasized. Please rewrite this section.

Response: Thank you for your comments. We have revised and shortened the introduction.

 

4. There is some redundancy in the Results and Discussion section, and there are too many segments that do not emphasize the key points. It is recommended to modify them.

Response: Thank you for your comments. We have revised the manuscript thoroughly.

 

 

5. All data in the Results and Discussion section should be kept to two significant figures.

Response: Thank you for your comments. We have revised the manuscript thoroughly.

 

6. The entire article is too long. It is recommended that some of the content in the Materials and Methods section, and some graphs and tables in the Results and Discussion section can be placed in the Supporting Materials.

Response: Thank you for your comments. We have revised the manuscript thoroughly.

 

 

Author Response File: Author Response.docx

Reviewer 2 Report

1. The paragraph including lines 326-343 is a description in detail of the table 3. The paragraph should give the reference to the table only

2. The terms "screening  values" and "screening procedures" emerge in 2.3 without any definition and explanation. The definition and clarifications should be made as this approach is used further for analysis

3.  The paragraph of lines 220-221states "The cancer unit risk estimates (UREs) and non-cancer reference concentrations (RfCs) were used to estimate the cancer and non-cancer risks". Here the reference concentrations for all compounds have to be given. Given paper references are not enough.

Moreover, the paper does not include non-cancer risk calculation results.

4.  The results of the cancer risk calculations are placed before the compound concentration data being the basis for said calculations. It seems not logical. The discussion of cancer risks might be moved toward the end of the article.

 

 

Author Response

Reply to reviewers’ comments

 

Manuscript ID: atmosphere-2521882

 

Title: Effect of Method Detection Limit on Health Risk Assessment of Hazardous Air Pollutants in an Urban Industrial Complex Area

Reviewer 2

 

1. The paragraph including lines 326-343 is a description in detail of the table The paragraph should give the reference to the table only

Response: Thank you for your comment. We have revised the paragraph and shortened them in the text.

 

 

2. The terms "screening values" and "screening procedures" emerge in 2.3 without any definition and explanation. The definition and clarifications should be made as this approach is used further for analysis

Response: Thank you for your comments. We have revised the paragraph.

 

 

3. The paragraph of lines 220-221states "The cancer unit risk estimates (UREs) and non-cancer reference concentrations (RfCs) were used to estimate the cancer and non-cancer risks". Here the reference concentrations for all compounds have to be given. Given paper references are not enough.

Response: Thank you for your comments. We have cited the reference for the UREs and RfCs.

 

4. Moreover, the paper does not include non-cancer risk calculation results.

Response: Thank you for your comments. We have added a table in the supplementary materials and explained the non-cancer risk (Table S9).

 

5. The results of the cancer risk calculations are placed before the compound concentration data being the basis for said calculations. It seems not logical. The discussion of cancer risks might be moved toward the end of the article.

Response: Thank you for your comment. We have rearranged the text and made it more logical.

 

 

Author Response File: Author Response.docx

Reviewer 3 Report

The article by Tsai et al. analyzes how the detection limit in hazardous air pollutant can influence the evaluation of the health risk.

I really enjoyed reading the article by Tsai et al., well written, clear and very relevant to the scientific community.

Please consider my comments and include suggested quotes, as well as fix small issues in the text.

The introduction is well written but far too long. I recommend shortening it, especially the VOCs part. I understand that it is one of the main topics of the article, but as it is presented it is very dispersive.

 

I suggest deleting the paragraph from lines 63 to 71: “In metropolitan Hong Kong…. Pose a significant risk to human health.”; and relocate the paragraph from lines 72 to 80: “Studies using Computer Programme to Calculate Emissions….Southern Coast Air Quality Management District.” This paragraph would be best placed on line 57, after “…[as suggested by 55 the International Agency for Research on Cancer (IARC, 2019)].” In this way the paragraphs relating to VOCs are placed below.

 

Also, I recommend cite the following articles in the sentence in lines 50-52: https://doi.org/10.1007/s10653-022-01403-9 and https://doi.org/10.1016/j.apr.2023.101787.

 

In lines 126-128 please cite the following article: https://doi.org/10.1016/j.scitotenv.2020.143384.

 

In lines 131-134 please cite the following articles: https://doi.org/10.1007/s10661-022-10107-7 and https://doi.org/10.1016/j.apgeochem.2021.105102.

 

Line 165: what do you mean by basic iron and basic aluminium?

 

Line 182: can you provide the detection limit of the GC-FID analysis?

 

Line 185: “The PM was determined using the PM10 sampler…”, which sampler was used? Please specify the type of instrument, the brand and the physical principle of this technique.

 

Line 187-189: please specify the ASTM method and cite the source.

 

Line 190: the method of TO-13A is also based on GC-FID analysis?

 

Table 1: Be inPM₁₀ → Be in PM₁₀

 

Table 1 (Note: line 232): NPM → NMP

 

Line 257: Is there a webpage of the TEDS? If exists, please insert it in the text.

How the emissions data was obtained? Please specify.

 

Table 4: why Cr(IV) was analyzed in TSP?

 

Line 389: please cite this article https://doi.org/10.1007/s10653-022-01403-9.

 

Table 6: the level of some hazardous air pollutant, such as cis-1,3-Dichloropropene, was zero, why? This contaminate hasn't been detected? or the detection limit of the instrument did not allow to detect this contaminant?

 

Figure 3: the variation in the different months, to which year does it refer? or is it an average of the years being analyzed? Please specify in caption.

 

Figure 4: in each plot the concentration of ng/m3 is specified, but ppb is specified on the side of the graphs. Please fix it.

Specify in the caption the analyzed years of this month.

Author Response

Reply to reviewers’ comments

 

Manuscript ID: atmosphere-2521882

 

Title: Effect of Method Detection Limit on Health Risk Assessment of Hazardous Air Pollutants in an Urban Industrial Complex Area

Reviewer 3

 

The article by Tsai et al. analyzes how the detection limit in hazardous air pollutant can influence the evaluation of the health risk.

I really enjoyed reading the article by Tsai et al., well written, clear and very relevant to the scientific community.

Please consider my comments and include suggested quotes, as well as fix small issues in the text.

Response: Thank you for your comments. We have revised the manuscript thoroughly.

 

1. The introduction is well written but far too long. I recommend shortening it, especially the VOCs part. I understand that it is one of the main topics of the article, but as it is presented it is very dispersive.

Response: Thank you for your comment. We have revised and shortened the introduction.

 

 

2. I suggest deleting the paragraph from lines 63 to 71: “In metropolitan Hong Kong…. Pose a significant risk to human health.”; and relocate the paragraph from lines 72 to 80: “Studies using Computer Programme to Calculate Emissions….Southern Coast Air Quality Management District.” This paragraph would be best placed on line 57, after “…[as suggested by 55 the International Agency for Research on Cancer (IARC, 2019)].” In this way the paragraphs relating to VOCs are placed below.

Response: Thank you for your comment. We have revised these paragraphs.

 

 

3. Also, I recommend cite the following articles in the sentence in lines 50-52: https://doi.org/10.1007/s10653-022-01403-9 and https://doi.org/10.1016/j.apr.2023.101787.

Response: I am sorry; one is not suitable for our manuscript for citation. One is the oxidative potential of metal pollution in urban dust and the other is mercury pollution from brick kilns. I selected to cite the article as follows:

[30] Schiavo, B., Meza-Figueroa, D., Vizuete-Jaramillo, E.et al. Oxidative potential of metal-polluted urban dust as a potential environmental stressor for chronic diseases. Environ Geochem Health45, 3229–3250 (2023). https://doi.org/10.1007/s10653-022-01403-9

 

4. In lines 126-128 please cite the following article: https://doi.org/10.1016/j.scitotenv.2020.143384.

Response: The article is presented the CeO₂-ZrO₂in dust from catalytic converters. It is a great job for publication in the Science of the Total Environment. However, it seems not to suit for citation in this article.

 

 

5. In lines 131-134 please cite the following articles: https://doi.org/10.1007/s10661-022-10107-7 and https://doi.org/10.1016/j.apgeochem.2021.105102.

Response: One of the articles is presented the gas phase mercury distribution in Mexico City and the other is presented the bioaccessibility of Mn in school dust. Both of them are not suitable for this manuscript.

 

 

6. Line 165: what do you mean by basic iron and basic aluminium?

Response: Thank you for your comment. It is the iron and steel industry and aluminum refinery industry.

 

 

7. Line 182: can you provide the detection limit of the GC-FID analysis?

Response: Thank you for your comment. We have provided the method detection limit of GC-FID in the supplementary material.

 

 

8. Line 185: “The PM was determined using the PM10 sampler…”, which sampler was used? Please specify the type of instrument, the brand and the physical principle of this technique.

Response: Thank you for your comment. We have explained the sampler of PM₁₀ (Tisch TE-6070 PM₁₀ High Volume Air Sampler, OH, USA).

 

 

9. Line 187-189: please specify the ASTM method and cite the source.

Response: Thank you for your comment. We have cited the source of the ASTM method.

[37] ASTM D7614-20, Standard Test Method for Determination of Total Suspended Particulate (TSP) Hexavalent Chromium in Ambient Air Analyzed by Ion Chromatography (IC) and Spectrophotometric Measurements. https://www.astm.org/d7614-20.html, (Accessed October 5, 2020)

 

 

10. Line 190: the method of TO-13A is also based on GC-FID analysis?

Response: BaP is analyzed following the method of TO-13A by Gas Chromatography/Mass Spectrometry (GC/MS).

 

 

11. Table 1: Be inPM10 → Be in PM10

Response: We have revised “ Be in PM₁₀”

 

 

12. Table 1 (Note: line 232): NPM → NMP

Response: We have revised it.

 

 

13. Line 257: Is there a webpage of the TEDS? If exists, please insert it in the text.

Response: Thank you for your comment. We have provided the reference.

[44]Taiwan Environmental Protection Agency (TEPA), (2021) Taiwan Air Pollutants Emission Data System, https://teds.epa.gov.tw/Introduction.aspx (access August, 26, 2021)

 

 

14. How the emissions data was obtained? Please specify.

Response: The emission data is in the Taiwan Emission Data System (TEDS) which is prepared by the Taiwan Environmental Administration.

[44]Taiwan Environmental Protection Agency (TEPA), (2021) Taiwan Air Pollutants Emission Data System, https://teds.epa.gov.tw/Introduction.aspx (access August, 26, 2021)

 

 

15. Table 4: why Cr(IV) was analyzed in TSP?

Response: It is followed the standard method of ASTM D7614.

[38] ASTM D7614-20, Standard Test Method for Determination of Total Suspended Particulate (TSP) Hexavalent Chromium in Ambient Air Analyzed by Ion Chromatography (IC) and Spectrophotometric Measurements. https://www.astm.org/d7614-20.html, (Accessed October 5, 2020)

 

 

 

16. Line 389: please cite this article https://doi.org/10.1007/s10653-022-01403-9.

Response: We have cited the reference. The work presented oxidative stress for chronic diseases from metal-polluted dust.

[30] Schiavo, B., Meza-Figueroa, D., Vizuete-Jaramillo, E.et al.Oxidative potential of metal-polluted urban dust as a potential environmental stressor for chronic diseases. Environ Geochem Health45, 3229–3250 (2023). https://doi.org/10.1007/s10653-022-01403-9

 

 

17. Table 6: the level of some hazardous air pollutant, such as cis-1,3-Dichloropropene, was zero, why? This contaminate hasn't been detected? or the detection limit of the instrument did not allow to detect this contaminant?

Response: Some compounds are not detectable in Table 5 for different sampling times. We have revised the table and explained the issue in the table.

 

 

18. Figure 3: the variation in the different months, to which year does it refer? or is it an average of the years being analyzed? Please specify in caption.

Response: Thank you for your comment. We have explained the yearly average in Figure 3.

 

 

19. Figure 4: in each plot the concentration of ng/m3 is specified, but ppb is specified on the side of the graphs. Please fix it.

Response: Thank you for your comment. We have revised the figure.

 

 

20. Specify in the caption the analyzed years of this month.

Response: Thank you for your comment. We have revised it.

Author Response File: Author Response.docx

Reviewer 4 Report

The manuscript submitted by Tsai and co-workers discusses how method detection limits and number of analysed samples can influence the health risk assessment of toxic air pollutants, focusing on volatile organic compounds (VOCs) and heavy metals present in the air particulate matter (PM).

The topic seems interesting and important, but authors fail to describe and discuss it. In fact, two thirds of the manuscript is devoted to describing the concentration, seasonal and monthly trends, and spatial distribution of the studied compounds, instead of focusing on the topic indicated in the title, which ends on the first page of the result and discussion section.

On the other hand, the manuscript is plenty of inaccuracies, poorly organised, with confusing and repetitive information, too long for the importance of the study, and redundant figures and tables. Moreover, some statements mentioned in the abstract and conclusions are not supported (or even, mentioned) in the results and discussion section (see comments below).

 

Detailed comments

Keywords. Try not repeat words already in the title as then you are not increasing the discoverability of your article via search engines.

Line 25 and 28 to 29. This conclusion is not mentioned in the corresponding section within Results and Discussion.

Line 58-59. One-third of all cancers in the USA since the 1990s have been due to exposure to ambient VOCs. Is it a prediction? How could they describe this in a reference from 1990?

Line 75. Write nitrogen in lower case letter.

Line 80. SCAQMD, 2015 is not in the reference list. Are these data from Europe? Please clarify as the paragraph begins with data from this continent.

Line 90. There are two references that could be cited as Li et al , 2021.

Line 91-92. Consider to rewrite this sentence, it seems as if BTEX come from biogenic emissions. On the other hand, this statement would probably be true for many regions of the world; however, it seems that the authors focus on studies in Asia, for this reason it is strange to mention here Canada. If you want to give a general overview, please include references from other regions besides Canada, otherwise limit it to Asia.

Line 98-99. Averaged emission profile of what?. In addition, this statement needs a reference.

Line 102-105. Reorganise the information in order to be more concise and clear. This paragraph could be combine with line 63.

Line 106-109. Where? In Hong Kong or in general? Which processes? The reference is focused on pharmaceutical production.

Line 112-113- Rewrite this sentence, it is confusing.

Line 151-152. I do not think these compounds have been determined in PM.

Line 180. It is not clear which compounds have been determined. These 71 VOCs are the target compounds or are they additionally analysed compounds?. In addition, in line 184 it is written 52 HAP species. Please, clarify.

Line 189. Correct Benzo(a)pyrene.

Perhaps is my fault, but I have not found table 1 cited in the text.

Line 272-273 give the same information than line 273-274. Combine them

Section 3.1. Is the main topic of the paper focused finally only on formaldehyde and acetaldehyde?. I addition, I would be expected that no risk assessment can be performed for compounds whose toxic concentrations in the air are lower than their method detection limits, it would not have sense. Please, explain of it is a common feature and how it is corrected (if it is).

Line 301-303. I do not understand this sentence, if the MDL is higher, then you cannot determine properly the cancer risk, can you? Please, clarify.

From line 355 to the end of the Results and Discussion section, the authors show and discuss results than do not have any relationship with the title of the paper. If they are interesting in including these results, they should consider changing the title. In addition, most of the information given in these subsections is the same than that given in the tables and figures. It is not necessary to repeat the number already in the tables and it is not necessary to give the same information as a Table and as a figure, for example  figure 6  shows the information of the last three columns of tables 4 and 5.

Table 5, most of the compounds show a concentration of 0.000±0.000. In one hand, it should be the MDL/2 and, on the other hand, these numbers do not correspond to the numbers that are mentioned in the text (from line 401 to line 475).

Line 470-471. This refers to the study area or a “general” heavily industrialized region, the text is confusing.

Spatial distribution. From line 520 to 534, authors are not describing neither discussing the spatial distribution of the analysing compounds. In addition, I would expect here a paragraph explaining the spatial distribution of heavy metals in PM that justifies the conclusions in lines 566-568 and in the abstract.

I would recommend that an expert review the English of the manuscript.

Author Response

Reply to reviewers’ comments

 

Manuscript ID: atmosphere-2521882

 

Title: Effect of Method Detection Limit on Health Risk Assessment of Hazardous Air Pollutants in an Urban Industrial Complex Area

Reviewer 4

The manuscript submitted by Tsai and co-workers discusses how method detection limits and number of analysed samples can influence the health risk assessment of toxic air pollutants, focusing on volatile organic compounds (VOCs) and heavy metals present in the air particulate matter (PM).

 

 

1. The topic seems interesting and important, but authors fail to describe and discuss it. In fact, two thirds of the manuscript is devoted to describing the concentration, seasonal and monthly trends, and spatial distribution of the studied compounds, instead of focusing on the topic indicated in the title, which ends on the first page of the result and discussion section.

Response: Thank you for your comments. We have revised the manuscript and emphasized the effects of MDL and sampler number on the work of health risk assessment.

 

 

2. On the other hand, the manuscript is plenty of inaccuracies, poorly organised, with confusing and repetitive information, too long for the importance of the study, and redundant figures and tables. Moreover, some statements mentioned in the abstract and conclusions are not supported (or even, mentioned) in the results and discussion section (see comments below).

Response: Thank you for your comment. We have revised the manuscript thoroughly.

 

 

Detailed comments

1. Try not repeat words already in the title as then you are not increasing the discoverability of your article via search engines.

Response: Thank you for your comment. We have revised the keywords.

 

2. Line 25 and 28 to 29. This conclusion is not mentioned in the corresponding section within Results and Discussion.

Response: Thank you for your comment. We have revised the paragraph in the abstract.

 

 

3. Line 58-59. One-third of all cancers in the USA since the 1990s have been due to exposure to ambient VOCs. Is it a prediction? How could they describe this in a reference from 1990?

Response: Thank you for your comment. We have revised the paragraph and made them clear.

 

4. Line 75. Write nitrogen in lower case letter.

Response: Thank you for your comment. We have revised it.

 

 

5. Line 80. SCAQMD, 2015 is not in the reference list. Are these data from Europe? Please clarify as the paragraph begins with data from this continent.

Response: Thank you for your comment. We have cited the reference in the manuscript.

[9] Southern Coast Air Quality Management District (SCAQMD), 2015. Multiple Air Toxics Exposure Study IV (MATES IV), Final Report. Diamond Bar, CA.

 

 

6. Line 90. There are two references that could be cited as Li et al , 2021.

Response: Thank you for your comment. We have revised it.

[18] Li, B., Ho, S. S. H., Qu, L., Gong, S., Ho, K. F., Zhao, D., Qi, Y., Chan, C. S., 2021. Temporal and spatial discrepancies of VOCs in an industrial-dominant city in China during summertime. Chemosphere 264, 128536.

[24] Li, F., Yan, J., Wei, Y., Zeng, J., Wang, X., Chen, X., Zhang, C., Li, W., Chen, M., Lü, G., 2021. PM2.5-bound heavy metals from the major cities in China: Spatiotemporal distribution, fuzzy exposure assessment and health risk management. J. Clean. Prod. 286, 124967.

 

 

7. Line 91-92. Consider to rewrite this sentence, it seems as if BTEX come from biogenic emissions. On the other hand, this statement would probably be true for many regions of the world; however, it seems that the authors focus on studies in Asia, for this reason it is strange to mention here Canada. If you want to give a general overview, please include references from other regions besides Canada, otherwise limit it to Asia.

Response: Thank you for your comment. We have revised the paragraph and made it clear.

 

 

 

8. Line 98-99. Averaged emission profile of what?. In addition, this statement needs a reference.

Response: Thank you for your comment. We have revised the paragraph and made them clear.

 

 

9. Line 102-105. Reorganise the information in order to be more concise and clear. This paragraph could be combine with line 63.

Response: Thank you for your comment. We have revised the paragraph and made them clear.

 

 

10. Line 106-109. Where? In Hong Kong or in general? Which processes? The reference is focused on pharmaceutical production.

Response: Thank you for your comment. We have revised the paragraph and made them clear.

 

11. Line 112-113- Rewrite this sentence, it is confusing.

Response: Thank you for your comment. We have revised it.

 

 

12. Line 151-152. I do not think these compounds have been determined in PM.

Response: Thank you for your comment. We have revised it.

 

13. Line 180. It is not clear which compounds have been determined. These 71 VOCs are the target compounds or are they additionally analysed compounds?. In addition, in line 184 it is written 52 HAP species. Please, clarify.

Response: Thank you for your comment. We have revised it.

 

 

14. Line 189. Correct Benzo(a)pyrene.

Response: Thank you for your comment. We have revised it.

 

 

15. Perhaps is my fault, but I have not found table 1 cited in the text.

Response: Thank you for your comment. We have checked the figures and tables cited in the text thoroughly.

 

 

16. Line 272-273 give the same information than line 273-274. Combine them

Response: Thank you for your comment. We have revised it.

 

17. Section 3.1. Is the main topic of the paper focused finally only on formaldehyde and acetaldehyde?. I addition, I would be expected that no risk assessment can be performed for compounds whose toxic concentrations in the air are lower than their method detection limits, it would not have sense. Please, explain of it is a common feature and how it is corrected (if it is).

Response: Thank you for your comment. We have revised and made it clear. The lower MDL could be more accuracy to determine the health risk from environmental chemical exposure.

 

 

18. Line 301-303. I do not understand this sentence, if the MDL is higher, then you cannot determine properly the cancer risk, can you? Please, clarify.

Response: Thank you for your comment. We have revised and made it clear.

 

19. From line 355 to the end of the Results and Discussion section, the authors show and discuss results than do not have any relationship with the title of the paper. If they are interesting in including these results, they should consider changing the title. In addition, most of the information given in these subsections is the same than that given in the tables and figures. It is not necessary to repeat the number already in the tables and it is not necessary to give the same information as a Table and as a figure, for example figure 6 shows the information of the last three columns of tables 4 and 5.

Response: Thank you for your comment. We have revised the manuscript thoroughly and made it clear

 

 

20. Table 5, most of the compounds show a concentration of 0.000±0.000. In one hand, it should be the MDL/2 and, on the other hand, these numbers do not correspond to the numbers that are mentioned in the text (from line 401 to line 475).

Response: Thank you for your comment. We have revised Table 5.

 

21. Line 470-471. This refers to the study area or a “general” heavily industrialized region, the text is confusing.

Response: Thank you for your comment. We have revised and made it clear.

 

 

22. Spatial distribution. From line 520 to 534, authors are not describing neither discussing the spatial distribution of the analysing compounds. In addition, I would expect here a paragraph explaining the spatial distribution of heavy metals in PM that justifies the conclusions in lines 566-568 and in the abstract.

Response: Thank you for your comment. We have added a paragraph to explain the distribution of heavy metals in PM.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Accepted in current form.

Reviewer 4 Report

I have revised the new version of the manuscript submitted by Tsai and co-workers. I found it quite difficult to see to what extent my comments had been taken into account, as in their replies the authors mostly just have written "we have revised it and made it clear". No further comment about the changes made or justification of those not made (if they disagreed with my suggestions). On the other hand, the revised version only marks in red the paragraphs that were supposed to have changed, but not the actual changes, as I could not find some of my former comments that I imagine resulted in text deletions.

Therefore, if I rely solely on the changes marked in red, I have to say that the authors have not considered most of my comments and have not implemented hardly any changes (and have not rebutted/explained why).

In particular, they have not taken into account the major problem of the manuscript which is that, if the main objective is to examine the effects of MDLs and sampling programmes on health risk assessment, why not mention it in the introduction by commenting on their starting hypothesis, reporting on previous publications on the subject (if any), etc. I insist again that if the paper is about something else, as it seems to be reading the introduction and the text dedicated to each result, they should change the title and the manuscript accordingly.