Current Status, Trends, and Future Directions in Chilean Air Quality: A Data-Driven Perspective

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The tone in this work is incorrect. A scientific article should avoid using a first person tone (ex. we). Please fix similar issues throughout the text.

In this work, the authors systematize all the information available from the SINCA network to evaluate the completeness of the records and the current trends of several pollutants in Chile. 

The citation formats used in this work are incorrect. Please follow the journal guidelines.

Section 2 Experimental should be combined with Section 3 Materials and Methods for better clarity and readability. 

FIgure 1 shows the map of Chilean air quality monitoring stations. However, it does not indicate whether these stations are roadside or background stations. 

Figure 4 shows the different trends of PM2.5, O3, and NOx in Santiago. What about the other pollutants such as PM10, SO2, and CO?

Figure 5 shows a temporal trend of PM2.5 and SO2 concentrations. Can the authors explain why is there a sudden peak in Coronel - PM2.5 daily concentration? Also, why is O3 not shown in Figure 5? 

In Figure 6, PM2.5 used the unit of ug/m3, while O3 and NOx used ppbv. Please consider using the same units as PM2.5 for better clarity and readability.

The conclusion section is clearly missing in this work, which is a major flaw. The limitations of this study were not discussed in this section. Also, the novelty of this work is unclear as it only analyses the past trends of air pollution in Chile. The authors also mentioned the use of machine learning being applied to this work, but it is nowhere to be found.

Author Response

The tone in this work is incorrect. A scientific article should avoid using a first person tone (ex. we). Please fix similar issues throughout the text.

Response: We corrected 3 places in the text where “we” was not the correct tone, especially in the last paragraph of the Introduction.

In this work, the authors systematize all the information available from the SINCA network to evaluate the completeness of the records and the current trends of several pollutants in Chile. 

The citation formats used in this work are incorrect. Please follow the journal guidelines.

Response: All references have been changed to a number in the text and the formatting of the references was changed according to the journal´s chosen format.

Section 2 Experimental should be combined with Section 3 Materials and Methods for better clarity and readability.

Response: Much of section 2 and 3 were combined and the details were taken out and placed in Section 1 of the supplementary Materials. We now only have 2. Experimental

Figure 1 shows the map of Chilean air quality monitoring stations. However, it does not indicate whether these stations are roadside or background stations.

Response: We added something in Figures 1 and before table 1 in the text we added “In Chile there is no classification of stations regarding the type of area (e.g. urban, suburban or rural) or according to the influence of the immediate surroundings (traffic, industrial or background) as in Europe and North America, they tend to all be in an urban or industrial settings - there are no background stations.”

Figure 4 shows the different trends of PM2.5, O3, and NOx in Santiago. What about the other pollutants such as PM10, SO2, and CO?

Response: We have mentioned that Figure S8 for SO2, CO and PM10 is in the Supplementary Materials

Figure 5 shows a temporal trend of PM2.5 and SO2 concentrations. Can the authors explain why is there a sudden peak in Coronel - PM2.5 daily concentration? Also, why is O3 not shown in Figure 5?

Response: O3 is not shown in this Figure because given they are coastal industrial zones, we are not concerned by high ozone levels here. The sudden peak in PM2.5 in Coronel

In Figure 6, PM2.5 used the unit of ug/m3, while O3 and NOx used ppbv. Please consider using the same units as PM2.5 for better clarity and readability.

Response: We have decided to have PM in ug/m3 and gases in ppbv and ppmv throughout the paper in the figures. We updated Table 1 which is now Table S1 to show both ppbv and ug/m3 for the gases but we state in section 2.4 that “PM₁₀ and PM_2.5 are displayed as µg m^-3 and NO₂, SO₂, CO and O₃ in ppbv mixing ratio (and CO in ppmv) in all the figures shown in this study and in all Chilean Air quality databases and reports.” As the gases are always shown as ppbv in Chilean law and monitroring.

The conclusion section is clearly missing in this work, which is a major flaw. The limitations of this study were not discussed in this section. Also, the novelty of this work is unclear as it only analyses the past trends of air pollution in Chile. The authors also mentioned the use of machine learning being applied to this work, but it is nowhere to be found.

We have improved the conclusions, mostly by taking out more explicative text from the results section. We have mentioned the limitations as being that we can only chose what the Government stations make available. But we have added the fact that these are only urban and industrial stations and that background or rural stations would be useful to install.

The novelty is in the fact that previous studies look at one particular region of chile or one type of pollutant and we have looked at all of the data to give an overview of the effectiveness  of the whole monitoring network.

We could include this in the discussion but in the end we didn’t- please comment:

“The only data used in this study were all the available SINCA monitoring stations and these are all based in urban or industrial zones. Chile has no long term background or baseline stations, so this could be seen as a limitation in this study, that we do not know what has happened to remote locations that may be affected by increased air pollutants after transport from nearby urban or industrial zones. However we belive this study is novel in that it has looked at pollution on a national scale and focusing on all the criteria pollutants, which as far as we know has never been done.”

 We removed the key word Machine learning

Reviewer 2 Report

Comments and Suggestions for Authors

The article is written chaotically and as presented does not meet the standards of scientific publications. Much irrelevant information is given. The Introduction section is excessively verbose, with few references. Why are sections 2. Experimental and 3. Materials and Methods separated? It is unclear. Section 4. Results should contain the results, and the text should refer to the figures/tables provided. Meanwhile, the Authors do not refer to Figues and it is not clear what they are discussing. Therefore, it is difficult to assess the results. Figure captions should be precise. The bibliographic descriptions are inconsistent.

Detailed comments:

1. The Introduction section contains comprehensive information on the background of the research and the general concept of the research. The text is written in a clear and logical style. I have no substantive comments, except for the way the bibliography is given. The bibliographic descriptions are inconsistent with the journal's editorial recommendations.
2. Table 2. WHO air quality limit levels for SO2 and O3 were entered incorrectly. Please correct. Also, I don't think the ClNAQS 8-hourly concentration is 40 μg/m3.
3. Figure 3. Unfortunately, I do not understand the idea of ​​Fig. 3 and the way of expressing this idea. The result is a colorful motley that is impossible to interpret. It's a pity that Figure 3 can't be enlarged while reading. It has very poor resolution and electronic magnification does not improve readability. Generally, the figures should be legible and allow reading the values ​​of the mean daily concentrations. I can only advise to give up unnecessary colors and show the values. The drawings can be black and white. The description before the Figure 3 is incomprehensible due to the illegibility of the Figure itself. I think they tried to present too much information in this Figure. I assume, because it wasn't written, that they tried to present medians for subsequent measurement years, for each station separately. An ambitious goal, but difficult to achieve, because there are so many stations. Maybe it would be better to present changes for macrozones.
4. Figure 5. This Figure do not present “Temporal trends of PM₂.₅ and SO₂ concentrations …”. It presents only time-series. This figure has an incorrect caption and is not discussed in the text.
5. 3. Industrial zone historical concentrations. What is discussed in this subsection? Literature information? Results should be discussed in this section. Discussion of other reports should be conducted in Chapter 4. Discussion.
6. Figure 6. This Figure do not present “Long-term trends of PM₂.₅, O₃, and NOₓ concentrations …”. It presents only time-series.
7. Chapter 4. Discussion is rather a Summary.

Author Response

The article is written chaotically and as presented does not meet the standards of scientific publications. Much irrelevant information is given. The Introduction section is excessively verbose, with few references. Why are sections 2. Experimental and 3. Materials and Methods separated? It is unclear. Section 4. Results should contain the results, and the text should refer to the figures/tables provided. Meanwhile, the Authors do not refer to Figues and it is not clear what they are discussing. Therefore, it is difficult to assess the results. Figure captions should be precise. The bibliographic descriptions are inconsistent.

Response: We have cited the Figures much more regularly in the text now

Much of section 2 and 3 were combined and the details were taken out and placed in Section 1 of the supplementary Materials. We now only have 2. Experimental

All references have been changed to a number in the text and the formatting of the references was changed according to the journal´s chosen format.

Detailed comments:

1. The Introduction section contains comprehensive information on the background of the research and the general concept of the research. The text is written in a clear and logical style. I have no substantive comments, except for the way the bibliography is given. The bibliographic descriptions are inconsistent with the journal's editorial recommendations.

Response: the references in the text have been changed from author to sequential numbers

Table 2. WHO air quality limit levels for SO2 and O3 were entered incorrectly. Please correct. Also, I don't think the ClNAQS 8-hourly concentration is 40 μg/m3. Response: Due to other reviewers comments we moved Table 1 and Table 2 to Tables S1 and S2 of Supplementary Materials and included both ppbv and ug/m3 but we have kept using ppbv in the graphs because in Chilean databases and Chilean laws are reported in ppbv for SO2, NOx and O3 and ppmv for CO.

SO2 and O3 CINAQS have been corrected.

Figure 3. Unfortunately, I do not understand the idea of ​​Fig. 3 and the way of expressing this idea. The result is a colorful motley that is impossible to interpret. It's a pity that Figure 3 can't be enlarged while reading. It has very poor resolution and electronic magnification does not improve readability. Generally, the figures should be legible and allow reading the values ​​of the mean daily concentrations. I can only advise to give up unnecessary colors and show the values. The drawings can be black and white. The description before the Figure 3 is incomprehensible due to the illegibility of the Figure itself. I think they tried to present too much information in this Figure. I assume, because it wasn't written, that they tried to present medians for subsequent measurement years, for each station separately. An ambitious goal, but difficult to achieve, because there are so many stations. Maybe it would be better to present changes for macrozones. Kevin

Response: A longer figure has been produced with the geographical zones colours removed for clarity and replaced with regional sections named in the caption. Only PM2.5 and PM10 are shown now. Figures S2, S3 and S4 show SO2, CO no, no2, nox and o3 with the new longer formatting were placed in the supplementary Materials.

Figure 5. This Figure do not present “Temporal trends of PM₂.₅ and SO₂ concentrations …”. It presents only time-series. This figure has an incorrect caption and is not discussed in the text.

Response: Temporal trends has been replaced with timeseries and the same in Figure 6.

3. Industrial zone historical concentrations. What is discussed in this subsection? Literature information? Results should be discussed in this section. Discussion of other reports should be conducted in Chapter 4. Discussion.

Response: we have taken discussions out  of the results section and increased the discussion in conclusions.

Figure 6. This Figure do not present “Long-term trends of PM₂.₅, O₃, and NOₓ concentrations …”. It presents only time-series.

Response: Temporal trends has been replaced with timeseries

Chapter 4. Discussion is rather a Summary.

We have improved the conclusions, mostly by taking out more explicative text from the results section. We have mentioned the limitations as being that we can only chose what the Government stations make available. But we have added the fact that these are only urban and industrial stations and that background or rural stations would be useful to install.

Reviewer 3 Report

Comments and Suggestions for Authors

The authors summarized the current state of air quality observations in Chile and analyzed the variation trends of several pollutants. I consider the topic significant and the presented data valuable. However, several issues need to be addressed before publication. 

1. The primary problem lies in that the overly detailed description of the observation network has obscured the purposes of this study. I suggest simplifying this kind of description in Section 1 and Section 2.1. 
2. The majority of the contents in the Introduction are not pertinent to the main aims of this study. 
3. Place Figure 1 in Section 2.2. 
4. Line 244, is it Section "2.2"? 
5. I suggest moving Section 2.4 to the supplementary materials. 
6. I suggest removing the contents regarding the softwares and tools, such as Section 3.1 and 3.2. 
7. I am unable to obtain the main information of Figure 3. I suggest making certain improvements. 
8. I suggest correcting "ug". 

Author Response

The authors summarized the current state of air quality observations in Chile and analyzed the variation trends of several pollutants. I consider the topic significant and the presented data valuable. However, several issues need to be addressed before publication. 

1. The primary problem lies in that the overly detailed description of the observation network has obscured the purposes of this study. I suggest simplifying this kind of description in Section 1 and Section 2.1.

Response: We have tried to reduce duplication in section 1 but believe it is useful to have a lot of background information here- there are few comprehensive studies of the whole AQ network in Chile

Much of section 2 and 3 were combined and the details were taken out and placed in Section 1 of the supplementary Materials. We now only have 2. Experimental

2. The majority of the contents in the Introduction are not pertinent to the main aims of this study.

Response: We believe it is useful to have a lot of background information here- there are few comprehensive studies of the whole AQ network in Chile

3. Place Figure 1 in Section 2.2.

Response: we have combined section 2 and 3 and believe fig 1 should stay where it is

4. Line 244, is it Section "2.2"? 

Response: The sections 2 and 3 have changed slightly and some been moved to supplementary Materials

5. I suggest moving Section 2.4 to the supplementary materials. 

Response: the technical details of the tools used have been moved to the supplementary section

6. I suggest removing the contents regarding the softwares and tools, such as Section 3.1 and 3.2.

Response: the technical details of the tools used have been moved to the supplementary section

7.I am unable to obtain the main information of Figure 3. I suggest making certain improvements.

Response: A longer figure has been produced with the geographical zones colours removed for clarity and replaced with regional sections named in the caption. Only PM2.5 and PM10 are shown now. Figures S2, S3 and S4 show SO2, CO no, no2, nox and o3 with the new longer formatting were placed in the supplementary Materials.

8.I suggest correcting "ug". 

Response: Any ug m^-3 in the figures has been replaced by µg m^-3.

 

 

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The quality of this manuscript has significantly improved after incorporating the reviewer's comments.

However, there are still some issues that exist throughout the text. 

The naming of the sections remained to be unusual, such as 2. Experimental should be Materials and Methods and a conclusion section is still missing.

It is clear that the authors ignored the recommendation to include a conclusion section, which is crucial in a scientific paper.

A conclusion should be a short and concise summary of the findings in this study.

The figure S8 in the supplementary section should be include in the main text.

The unit of concentration should follow those used in the WHO air quality guideline, which is micrograms per cubic meter.

Comments on the Quality of English Language

Some of the in-text citations and references are still missing. Please fix similar problems throughout the text. 

Author Response

The quality of this manuscript has significantly improved after incorporating the reviewer's comments. However, there are still some issues that exist throughout the text. 

The naming of the sections remained to be unusual, such as 2. Experimental should be Materials and Methods and a conclusion section is still missing.

Reply: We have changed it to 2. Materials and Methods. And changed 2.5 to 2.5 Statistical analyses

It is clear that the authors ignored the recommendation to include a conclusion section, which is crucial in a scientific paper. A conclusion should be a short and concise summary of the findings in this study.

Response: Thank you! Sorry, now we have closely looked at other papers in this journal, we understand we missed this out! We have put a short conclusion section in after the discussion.

The figure S8 in the supplementary section should be include in the main text.

Response: We had already introduced Figure S8 in the text (just above Figure 4).

The unit of concentration should follow those used in the WHO air quality guideline, which is micrograms per cubic meter.

Response: We still want to stick to our idea of showing in ppbv- we will include the conversion to ug/m3 in each caption of the main section. And in Table S2 we include the conversion to ug/m3.

Many important reputable papers use ppbv mixing ratio for ozone, NOx and SO2 and ppm for CO; https://online.ucpress.edu/elementa/article/doi/10.1525/elementa.273/112792/Tropospheric-Ozone-Assessment-Report-Present-day, https://repositorio.uchile.cl/handle/2250/175465, https://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072021000305259, https://link.springer.com/article/10.1007/s11869-013-0218-7 (for VOC, NOx) as well

Comments on the Quality of English Language: Some of the in-text citations and references are still missing. Please fix similar problems throughout the text. 

Response: We reviewed the text to find references that were missing or numbering that was wrong, We found a reference 34 that should be 31. Line 574 we found references 18 and 36 were in fact 15 and 33. and reference 50 was actually 45. Thank you!

 

Reviewer 3 Report

Comments and Suggestions for Authors

I have no more comments.

Author Response

Thanks for your two reviews!