Air Quality at Your Street 2.0—Air Quality Modelling for All Streets in Denmark

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

General comment

 

The paper reports an investigation of the model performances for air quality at all streets in Denmark discussing spatial variability and the compliance with EU regulations and WHO indications. The topic is of interest and the results useful for the scientific community, however, some aspects are not completely clear and a revision following my specific comments is suggested.

 

Specific comments

 

Lines 208-209. Here it should be mentioned that eBC is often evaluated using a MAC derived from EC so that it is essentially representing EC measured with an optical approach, mentioning the recent work of Merico et al (Atmospheric Pollution Research, 102668, 2025).

 

Line 277. 500 what? Figure 1, please add measurement units, what is vehicles per day?

 

Lines 320-323. Essentially, traffic of 2015 was considered for simulation in 2019. Is this reasonable? What kind of uncertainty could result from this?

 

Caption of figure 2.2. What “velocity” is km/t?

 

Lines 380-382 and the conclusions drawn from this comparison. What is the meaning to compare modelling of 2019 with measurements of 2020, considering also that 2020 is a particular year because of COVID-19 restrictions. I would not draw any real conclusion from this. The same apply for the comparison in lines 430-432.

 

The comparisons shown in supplementary material demonstrate that model performances are quite different for the different typologies of sites. This should be interpreted and commented.

Author Response

Please see comments in the attached file.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript presents Air Quality at Your Street 2.0, an advanced multi-scale air quality modelling system applied across all Danish addresses for 2019. The study combines regional, urban, and street-level chemistry-transport models (DEHM/UBM/OSPM) and integrates real traffic data, meteorology, and emission inventories. The work offers a national-scale, high-resolution analysis with direct public accessibility through an online platform.

1. Technical Highlights
   （1） Multi-scale coupling: The paper effectively describes how DEHM provides regional input to UBM and OSPM, achieving a consistent nesting from hemispheric to street level (5.6 km → 1 km → address scale).
   （2） Validation: Strong correlation with Danish Air Quality Monitoring Programme data (R² up to 0.96 for NO₂, 0.84–0.86 for PM).
   （3） Traffic input: The integration of Green Mobility Model (GMM) traffic flows and SpeedMap GPS data significantly enhances realism compared with earlier studies.
   （4） Adjustment for mass closure: Application of an empirical 1.33 correction factor for PM₂.₅/PM₁₀ addresses underestimation bias and ensures comparability with regulatory limits.
   （5） Comprehensive uncertainty discussion: Limitations near highways, intersections, and wood-burning areas are transparently analyzed.
2. Major Comments and Recommendations
   （1） Clarify the novelty:
   The manuscript should explicitly highlight what technical developments distinguish Air Quality at Your Street 2.0 from version 1.0 and other European mapping systems (e.g., SHMI Sweden 2023). In addition, a summary table comparing input data, pollutants, and resolution between versions would strengthen the claim of innovation.
   （2） PNC uncertainty:
   The overestimation of background and underestimation of street PNC should be analyzed quantitatively (e.g., bias statistics, sensitivity analysis).     Recommend discussing possible methodological improvements (e.g., updated emission factors, nucleation modelling, or hybrid measurement–model assimilation).
   （3） Model evaluation:
   The validation section could include statistical indicators (MB, NMB, RMSE, IOA) in tabular form for all pollutants to facilitate reproducibility and transparency.
   （4） Policy relevance and public communication:
   Since the work aims to inform policy and the public, a concise discussion on how this system supports EU 2024 Directive compliance and urban air-quality planning would enhance impact.
   （5） Figures:
   Improve readability of Figures 3.4–3.8 (maps). Add scale bars and consistent legends to allow quantitative interpretation of concentration gradients.
3. additional aspects

   (1) Line 23–25: Replace “supports national-scale assessment” with “supports high-resolution national-scale assessment and citizen access.”
   (2) Section 2.1.2: Provide a brief justification or reference for the chosen correction factor 1.33 beyond prior literature (e.g., whether it remains stable across years).
   (3) Section 3.3: Specify the exact percentage of addresses exceeding new EU and WHO limits to better illustrate exposure magnitude.
   (4) Conclusion: Suggest highlighting potential for model application beyond Denmark and possible coupling with population exposure or health impact models.

    

4. Additional Comment on Data Timeliness and Post-COVID Relevance
   While the study provides a comprehensive and technically robust evaluation of Danish air quality for the year 2019, the reliance on pre-pandemic data raises concerns regarding the current relevance of the findings. The year 2019 represents the last full year before the COVID-19 pandemic, during which substantial and well-documented changes in mobility patterns, traffic emissions, and industrial activity occurred across Europe. These changes, along with subsequent economic and behavioral adjustments, have likely altered emission inventories and urban air-quality dynamics.
   Therefore, I recommend that the authors:
   （1） Acknowledge this limitation explicitly in the Discussion or Conclusion section, emphasizing that 2019 provides a valuable baseline but may not reflect post-pandemic emission conditions.
   （2） Discuss potential implications of COVID-19–related emission reductions and recovery trends on future applications of the Air Quality at Your Street modelling framework.
   （3） Suggest future updates using more recent traffic, emission, and monitoring data (e.g., 2020–2024) to assess temporal changes and validate the model’s adaptability to evolving environmental conditions.
   Including this discussion would significantly strengthen the manuscript’s scientific relevance and temporal context, demonstrating awareness of recent global developments in air quality and emission dynamics.

 

 

 

 

 

Comments on the Quality of English Language

Language and Formatting
(1) The manuscript is clearly written, but the overall length could be reduced to improve focus and readability.
(2) Minor language tightening is advised for conciseness.
(3) Ensure consistent reference formatting (e.g., remove duplicated years, unify “et al.” style).
(4) Review spacing and typographic details (e.g., “µg/m³,” “PM₂.₅,” “NO₂”) to meet Atmosphere style guidelines.

Author Response

Please see comments in the attached file.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript entitled “Air Quality at Your Street 2.0 – Air Quality Modelling for All Streets in Denmark” presents a national-scale, high-resolution modelling framework integrating the DEHM/UBM/OSPM model chain within the AirGIS system to estimate annual mean concentrations of NO₂, PM₂.₅, PM₁₀, BC, and PNC for all Danish addresses in 2019. The study expands on previous efforts by including additional pollutants (BC and PNC) and updating the simulation period from 2012 to 2019. The modelling framework itself is scientifically solid and well established, and the topic is relevant for both scientific and policy purposes, given its potential to support local air quality management and exposure assessment in Denmark. However, despite these positive aspects, the manuscript raises serious ethical and structural concerns related to extensive text overlap with the authors’ own previous publication (Jensen et al., 2017, Transportation Research Part D) and the technical report “LUFTEN PÅ DIN VEJ 2.0” (2021). The iThenticate report shows 52% similarity, and manual inspection confirms that large portions of the Introduction and Methodology are reproduced almost verbatim or with minimal paraphrasing from the 2017 paper. Substantial textual overlap is found in the descriptions of DEHM, UBM, OSPM, and the AirGIS system, as well as in general background paragraphs on air pollution and regulatory frameworks. This level of duplication exceeds acceptable standards of methodological repetition and constitutes self-plagiarism. Although the authors implicitly acknowledge that this is an updated version of a previous study, they do not clearly explain what has been reused, what has been expanded, and what is truly new in this version.

The authors need to completely reformulate the presentation and structure of the manuscript. The Introduction and Methodology, in particular, must be rewritten to remove the large portions of repeated text. The paper should explicitly and transparently acknowledge the existence of the previous version (Air Quality at Your Street 1.0) and clearly describe how this work represents an extension or update. The Introduction should contextualize the evolution of the project, briefly referring to the 2017 publication and the “LUFTEN PÅ DIN VEJ 2.0” report, while focusing on the motivations and new objectives of the 2.0 version. In the Methodology, instead of repeating detailed model descriptions already published, the authors should summarize the general model framework concisely, cite the 2017 paper for detailed formulations, and focus their writing on what has changed or improved (e.g., new pollutants, updated traffic and emission inventories, refined meteorology, and new validation datasets). This approach will make the manuscript more concise and scientifically transparent while avoiding redundancy and text recycling. Only after these substantial revisions can the manuscript be further considered.

Author Response

Please see comments in the attached file.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

This manuscript presents modelled annual mean concentrations of NO₂, PM2.5, PM₁₀, Black Carbon (BC), and Particle Number Concentration (PNC) for all ~2.5 million Danish addresses in 2019 using the Air Quality at Your Street 2.0 system. The modelling framework combines coupled chemistry-transport models (DEHM/UBM/OSPM) with input from the Green Mobility Model and GPS-based vehicle speed data. Model outputs were evaluated against observations from the Danish Air Quality Monitoring Programme, showing strong agreement for NO₂, PM2.5, PM₁₀, and BC, but notable overestimation of PNC background levels and underestimation of street contributions. Indicative exceedances of NO₂ EU limit values decreased markedly from 2012 to 2019, while exceedances of updated EU and WHO guidelines persist, especially for particulate matter. This work identifies key sources of model uncertainty and supports national-scale assessment, policy development, and public access via an interactive map (http://luftenpaadinvej.au.dk). It is interesting and it is relevant and within the scope of the journal.

The paper has certain novelty and advantages for this field research work, and has value for publishing in the Journal. Therefore, I suggest that this paper be accepted with further modification.

1 Figure 3.2 Add a and b to the image

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5 Figure 3.7a. Figure 3.7b Add a and b to the image

6. Through further proofreading, the quality of this article should be greatly improved.

Author Response

Please see comments in the attached file.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I accept the authors’ revisions to the manuscript. I have no further comments or questions.

Author Response

Thank you for the assessment.

Reviewer 3 Report

Comments and Suggestions for Authors

The revised manuscript shows substantial improvement in several aspects. The authors have made the Introduction and Methodology more concise, which has enhanced the overall readability and scientific presentation of the paper. Additionally, the inclusion of perspectives raised by other reviewers has added interesting dimensions to the work. Nevertheless, I still have several comments and suggestions that require attention, detailed below.

(1) Although the authors have shortened the text, thereby reducing the similarity percentage with their previous 2017 paper (“Air Quality at Your Street 1.0”) and the technical report mentioned earlier, significant overlap remains, particularly in the Introduction and in the section discussing the study’s limitations. Regarding the latter, the same limitations described in the 2017 study are essentially repeated here, both in content and wording. I find it important to question whether none of those limitations have been overcome given the technological and methodological advances of the past decade. To make this section more engaging and informative, I suggest reframing it along the lines of “These limitations reflected the state of the system in 2017 [...], since then, several aspects have been improved [cite them], but others still persist [...]” As for the Introduction, the first paragraph is almost a direct reproduction of half of the fourth paragraph from your 2017 paper. It would benefit greatly from a refreshed perspective, start by framing the current european context of air pollution. Much has changed since 2017 (health and economic impacts; guidelines...) it would be valuable to open with a broader, updated discussion rather than reusing the same wording.

(2) Some structural adjustments are still needed. In Section 3 (“Results”), subsections 3.1 and 3.3 include unnumbered headings inserted within the text for “NO₂,” “PM₂.₅ and PM₁₀,” “BC,” and “PNC.” These are not true subsections, and their current format disrupts the flow. I suggest either removing these headings and ensuring smooth transitions between pollutants or numbering them properly as subitems. Another organizational improvement concerns Sections 3.5 (“Comparison with similar systems”) and 3.6 (“Potential transferability and scalability”): both would be better placed before the section on study limitations. The limitations should appear as the final subsection of your Results and Discussion. Finally, since the current Section 3 already incorporates interpretative discussion, I recommend renaming it from “Results” to “Results and Discussion.”

Author Response

All suggestions have been followed. Please find our point-to-point comments in the attachment.

Author Response File: Author Response.pdf