Air Quality in the Italian Northwestern Alps during Year 2020: Assessment of the COVID-19 «Lockdown Effect» from Multi-Technique Observations and Models

Round 1

Reviewer 1 Report

The paper is interesting and deserves publication. 

In my view, the authors should only include a mentioning in the introduction of the impact of seaports as 'air pollution hub', see e.g. https://link.springer.com/chapter/10.1007/978-3-030-39990-0_10

Should the reader have an interest for the SOX then the same source provides a detailed analysis on the subject matter https://www.nomos-elibrary.de/10.5771/9783845271873-607/ii-commentary-on-directive-1999-32-ec-as-regards-the-sulphur-content-of-marine-fuels-as-amended-by-directive-2012-33-ec

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

This manuscript investigates the air quality in Alps by using different observations and models and further analyzes the effects of lockdown. I only have a few comments for the authors. My recommendation is to accept it after minor revision.

1. The manuscript is well written, but the content of this article is too long. I suggested that the author should try to reduce the content of the article.
2. The authors cited too many references, which looks like a review paper, but this is an original article. The authors can remove some references.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

What is novel about this study?  There is a focus on pristine mountain areas rather than polluted towns and year-round rather than the first wave. Use of predictive statistical models to take meteorology into account

Is the introduction section sufficiently clear?

In the section introduction, a set of research questions are listed as bullet points. This is a great approach that sets the tone for the reader to start following along easily.

Methods Section

The experimental set-up for this study appears to be really thorough and uses extensive in-situ surface measurements and vertical profiles. This section is described to the very last detail including the inversion codes used which would be very useful for any other research team trying to reproduce the results

An average of 5 years spanning from 2015- 2019 is used as a reference for ‘business-as-usual/normal conditions. There is a mention of finding a balance between having enough data to provide a reasonable average and avoiding any long term meteorological trends.

What metrics help the authors choose a time span of five years? It is mentioned that 5 years is believed to be a good compromise but it would be good to get some more clarity in this regard.

Results/ Discussion

The subject matter is of great interest for our time. Although several research papers have been published on the variation of NOx and aerosols over the past year, this one shifts the focus from highly populated areas to a pristine valley. The limitations in the availability of high-altitude data make the scope of this study limited. The addition of vertical profiles acts as a partial integration. It is up to the editorial committee to decide if the contribution is significant enough for publication but as a scientific research paper, this was very comprehensive and well structured.

In addition to the box plots, some visualization of Nox and aerosol variation in the form of maps would be helpful in following the trends easier.

Minor printing errors

Line 25: throughout years to throughout the years

Line 29: similarly to à similar to or similarly

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

The content of the submitted manuscript is good but the presentation way of current form is not fulfilling the journal requirements. Modification is needed to consider for publication.

  - Title of the paper

The title of the paper looks good but in the same time, it can be modified to represent the manuscript in a better way.

Abstract

-          The abstract is not well written

-          You should include some of the main findings in the abstract section.

The abstract should have a conclusion of the study.

Introduction  

• The objective of the study is also not clearly mention.
• Add more on the basic of the problem in the introduction
• More details about COVID-19 are required in the introduction section.
• The author should focus mainly on the importance and significance of the study.
• I suggest the author to demonstrate what does the paper add to the current literature? and what new knowledge is added by this study?
  
  

Literature review part is need to be updated.

Include a table Like

Add the unique of this study compared to other studies discuss the same issue.

-Discus merits and limitations of technique applied.

 Material and Methods

-     The material and method section is too weak in the manuscript and you need to focus on it more.

Result and discussion

• The presentation fails to discuss the summary, and trying to some of vague reason which is not the explanation.
• The explanation for the critical analysis is not sufficient, although some of the good points have has been identified.

Conclusion

-          Please rewrite the conclusion with the proper explanation in the R & D.

References

Reference section should be increased with number of recent studies. I would like to suggest to author to include following published article to improve the quality of articles, these are

Bherwani H, Anjum S, Kumar S, et al. 2020. Understanding COVID-19 Transmission through Bayesian Probabilistic Modelling and GIS Based Voronoi Approach: A Policy Perspective. Environmental Development and Sustainability. DOI: 10.1007/s10668-020-00849-0.

Gautam S. 2020 The influence of COVID – 19 on air quality in India: A boon or inutile. Bulletin of Environmental Contamination and Toxicology 104(6): 724-726.

Gupta A, Bherwani H et al. 2020. Air pollution aggravating COVID‑19 lethality? Exploration in Asian cities using statistical models. Environment Development and Sustainability, DOI:10.1007/s10668-020-00878-9.

Bherwani H, Nair M, Musugu K et al. 2020. Valuation of air pollution externalities: comparative assessment of economic damage and emission reduction under COVID-19 lockdown. Air Quality Atmosphere and Health DOI: 10.1007/s11869-020-00845-3.

Gautam S. 2020. COVID – 19: Air pollution remains low as people stay at home. Air Quality Atmosphere and Health DOI: 10.1007/s11869-020-00842-6.

Ambade B et al. 2021. COVID-19 lockdowns reduce the Black carbon and polycyclic aromatic hydrocarbons of the Asian atmosphere: source apportionment and health hazard evaluation. Environmental Development and Sustainability DoI.org/10.1007/s10668-020-01167-1.  

Gautam AS, Dilwaliya N et al. 2020. Temporary reduction in air pollution due to anthropogenic activity switch‑of during COVID‑19 lockdown in northern parts of India. Environmental Development and Sustainability. DOI: 10.1007/s10668-020-00994-6.

Other comments:

English editing is needed in some parts of the manuscript.
Abbreviations should be explained before the introduction.

Author Response

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Author Response File: Author Response.pdf