Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors, I believe that your manuscript is well written. I have a few comments, as follows:

1. The introduction is very long, and the first half contains generally known information. It would also be worth adding that PM2.5 pollution may consist not only of solid particles but also of acidic aerosols containing CO₂.

2. How do photocatalytic processes in the atmospheric air affect NO₂ concentrations? What is the seasonal variation of this oxide in the air?

3. What other known methods exist to reduce pollution from vehicle traffic, and are they applied? Please analyze them and highlight why your method is the best from both environmental and economic perspectives.

4. In my opinion, the conclusion in the manuscript is too long. Please shorten it according to the objective stated in the Introduction.

5. I also believe that the scientific novelty should be emphasized in the Introduction. This would enhance the scientific value of your manuscript.

with Regards

Author Response

We thank the reviewer for his helpful comments. We have responded to all comments in the following. The authors hope that all responses to the comments are substantive and sufficient.

Yellow colour in the article text.

1. The introduction is very long, and the first half contains generally known information. It would also be worth adding that PM2.5 pollution may consist not only of solid particles but also of acidic aerosols containing CO₂.

Thank you for this comment. In the introduction, we tried to emphasize the importance of this issue with some information that is known but has a fundamental relationship to this study. However, we appreciate the reviewer's recommendation and have shortened the introduction and added some information about acidic aerosols containing CO₂.

1. How do photocatalytic processes in the atmospheric air affect NO₂ concentrations? What is the seasonal variation of this oxide in the air?

Thank you for this comment. This information is really worth mentioning in the article. We have added a short text to the article discussion.

1. What other known methods exist to reduce pollution from vehicle traffic, and are they applied? Please analyze them and highlight why your method is the best from both environmental and economic perspectives.

Thank you for this comment. We have added a short text to the article discussion.

1. In my opinion, the conclusion in the manuscript is too long. Please shorten it according to the objective stated in the Introduction.

Thank you for this comment. The conclusions chapter was made shorter.

1. I also believe that the scientific novelty should be emphasized in the Introduction. This would enhance the scientific value of your manuscript.

Thank you for this comment. We have added a short text to the article introduction.

 

Green colour in the article text.

The English has been checked and some parts have been improved for a clearer expression of the research.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The topic discussed in the manuscript entitled Modeling and Measurements of Traffic-related PM10, PM2.5, 2 and NO2 emissions around the Roundabout and Three-arm Intersection in the Urban Environment is interesting and concerns current problems related to air quality. The research topic and objective are clearly presented. The original three-arm intersection was rebuilt into a roundabout. The motivation for this study was the question of what such a change in the layout of the intersection would mean in terms of the production of pollutants from road traffic. The presented research results are not necessarily obvious, but very interesting.

Please review and correct the following comments:

- Lines 327-328, Maintain consistency in the names of chemical compounds using chemical formulas; this comment applies to the entire manuscript.

- Correct the References.

- Be sure to check the literature links; some of the links provided do not refer to the cited literature, e.g., reference 36.

Correct all references so that the link directly links to the article, e.g., 19 https://doi.org/10.1016/j.envres.2025.122134 instead of doi:10.1016/J.ENVRES.2025.122134.

25, 27, 39 – Correct according to the instructions for authors.

Author Response

We thank the reviewer for the helpful comments. We have responded to all comments in the following. The authors hope that all responses to the comments are substantive and sufficient.

- Lines 327-328, Maintain consistency in the names of chemical compounds using chemical formulas; this comment applies to the entire manuscript.

The chemical formulas were checked and any deficiencies were eliminated.

- Correct the References.

- Be sure to check the literature links; some of the links provided do not refer to the cited literature, e.g., reference 36.

- Correct all references so that the link directly links to the article, e.g., 19 https://doi.org/10.1016/j.envres.2025.122134 instead of doi:10.1016/J.ENVRES.2025.122134.

- 25, 27, 39 – Correct according to the instructions for authors.

References have been checked and direct links to relevant articles have been added. Thank you for the excellent observation, reference 36 has been corrected.

Reviewer 3 Report

Comments and Suggestions for Authors

This is an interesting and well-executed study that combines field measurements with dispersion and microsimulation modeling to evaluate the impact of converting a three-arm intersection into a roundabout on local air quality. The dual approach of empirical monitoring and modeling adds credibility, and the discussion effectively highlights the trade-offs between reductions in particulate matter and increases in NO₂ concentrations. However, a few methodological clarifications and contextual enhancements would further strengthen the paper.

1) Could the authors elaborate more on the representativeness of the one-week monitoring periods in 2016 and 2017? How might seasonal variability affect the generalizability of the results?

2) The paper mentions that NO2 increased by 143% while PM fractions decreased at the roundabout. Can the authors provide additional mechanistic explanation or modeling evidence that links vehicle acceleration/deceleration cycles directly to the observed NO2 increase?

3) In the field measurements, were background concentrations of PM and NO2 controlled for or measured at a nearby reference site to separate local intersection impacts from regional background levels?

4) The discussion notes that the coarse PM2.5-10 fraction was most reduced at the roundabout. Could the authors expand on how changes in surrounding land use (e.g., paved vs. unpaved areas) may have influenced resuspension contributions?

5) The modeling section is comprehensive, but more detail on the validation of CadnaA outputs with field data would be useful. For example, what was the correlation or error margin between modeled and measured concentrations?

6) The discussion is insufficient. A more detailed interpretation of the results and a richer perspective on future directions are needed. In particular, roads significantly influence air mobility and pollution concentrations. Emerging contaminants, such as microplastics, are also becoming important issues in roadside air pollution. Please consider strengthening the discussion with these aspects (ref: https://doi.org/10.1016/j.trac.2024.117859).

7) Finally, could the authors comment on the broader implications for urban planning; whether reductions in PM but increases in NO2 should favor roundabout adoption, or if additional mitigation is needed?

Author Response

We thank the reviewer for his helpful comments. We have responded to all comments in the following. The authors hope that all responses to the comments are substantive and sufficient.

Blue colour in the article text.

• Could the authors elaborate more on the representativeness of the one-week monitoring periods in 2016 and 2017? How might seasonal variability affect the generalizability of the results?

Thank you for this comment. We have added a short text to the article methodology and discussion as well.

• The paper mentions that NO2 increased by 143% while PM fractions decreased at the roundabout. Can the authors provide additional mechanistic explanation or modeling evidence that links vehicle acceleration/deceleration cycles directly to the observed NO2 increase?

Thank you for this comment. We have added a short text to the article discussion as well.

• In the field measurements, were background concentrations of PM and NO2 controlled for or measured at a nearby reference site to separate local intersection impacts from regional background levels?

These data were not collected and subsequently correlated with the measurements made at the intersection. It is possible that background plays a significant role in pollutant concentrations. However, in this case, the background was not investigated and separated from the measured concentrations.

• The discussion notes that the coarse PM2.5-10 fraction was most reduced at the roundabout. Could the authors expand on how changes in surrounding land use (e.g., paved vs. unpaved areas) may have influenced resuspension contributions?

Thank you for this comment. We have added a explanation of road dust resuspension reduction to the article discussion.

• The modeling section is comprehensive, but more detail on the validation of CadnaA outputs with field data would be useful. For example, what was the correlation or error margin between modeled and measured concentrations?

In the case of modeling in the CadnaA program, one variant of the model setting was used according to the detected traffic intensities at the intersection. This primarily involved determining the change in concentrations using the model based on the change in the intersection structure at a given traffic intensity. Multiple modeling scenarios (say, for each day of the week) were not performed for possible comparison with field simulations. But we thank the reviewer for the stimulating comment, which we may use in other similar studies.

• The discussion is insufficient. A more detailed interpretation of the results and a richer perspective on future directions are needed. In particular, roads significantly influence air mobility and pollution concentrations. Emerging contaminants, such as microplastics, are also becoming important issues in roadside air pollution. Please consider strengthening the discussion with these aspects (ref: https://doi.org/10.1016/j.trac.2024.117859).

Thank you for this comment. We understand your comment. However, it is sometimes difficult to cover the entire area of ​​the problem in one study. We have tried to appropriately include some other facts of this problem in the discussion and we hope that this will be sufficient. The discussion has been fundamentally expanded.

• Finally, could the authors comment on the broader implications for urban planning; whether reductions in PM but increases in NO2 should favor roundabout adoption, or if additional mitigation is needed?

Thank you for this comment. You will certainly agree with us that such a statement is difficult to implement in practice. No solution is without compromises. Roundabouts also have other benefits that are also important for the quality functioning of the road network. In the conclusions, we have listed some assumptions for the effective implementation of roundabouts, also from the perspective of improving air quality.

Author Response File: Author Response.docx