Preprints
https://doi.org/10.5194/egusphere-2026-341
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/egusphere-2026-341
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
17 Mar 2026
| 17 Mar 2026
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
Quantifying the impact of vehicle fleet electrification on local aerosol concentrations in Helsinki using high-resolution Large Eddy Simulation
Abstract. Urban air quality strategies increasingly rely on transitioning to battery electric vehicles (BEVs), yet their impact on non-exhaust aerosol emissions remains uncertain. This study uses high-resolution Large Eddy Simulation (LES) to investigate aerosol concentrations in a planned Helsinki neighborhood where a highway corridor is being converted into a residential boulevard. We consider three scenarios with varying BEVs shares: a baseline year 2022 (10 % of BEVs), and projected years 2035 (60 %) and 2040 (100 %).
The findings reveal a "dual impact" of vehicle electrification. Increased BEV shares significantly reduce particle number concentrations (PN2.5), with a projected 60 % decrease by 2040 compared to the baseline. Conversely, fine particle mass (PM2.5) is projected to increase by approximately 15 % by 2040. This divergence occurs because while BEVs eliminate tailpipe exhaust, their greater weight increases unregulated non-exhaust emissions (NEE) from tire and brake wear. Results show high spatial variation, with pollutants concentrated along boulevard roads and limited penetration into residential blocks. This study underscores the challenges of BEV adoption in realistic urban environments and provides vital insights for sustainable urban planning and pollution mitigation strategies.
How to cite. Atashi, N., Li, X., Karttunen, S., Viri, R., Harrison, R., Strömberg, J., Kaltianen, A., Leinonen, M., Ruotsalainen, L., and Järvi, L.: Quantifying the impact of vehicle fleet electrification on local aerosol concentrations in Helsinki using high-resolution Large Eddy Simulation, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2026-341, 2026.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
Download & links
- Preprint
(15472 KB) - Metadata XML
-
Supplement
(2935 KB) - BibTeX
- EndNote
Status: open (until 29 Jun 2026)
Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor
| : Report abuse
- RC1: 'Comment on egusphere-2026-341', Anonymous Referee #1, 17 Jun 2026 reply
-
RC2: 'Comment on egusphere-2026-341', Anonymous Referee #2, 18 Jun 2026
reply
General Comments
This manuscript describes a Large Eddy Simulation (LES) study investigating aerosol concentrations in a planned urban boulevard in Helsinki under three vehicle electrification scenarios. The topic is timely and the application of high-resolution LES to a realistic urban planning context is commendable.
However, this paper has several shortcomings. The LES simulation covers only two hours, which raise questions about the reliability. The model results also lack observational data for model validation, undermining the credibility of the quantitative findings. Furthermore, restricting the analysis to morning peak hour conditions introduces potential systematic bias, as emission characteristics, dispersion patterns, and traffic compositions vary substantially across the diurnal cycle and seasons. The manuscript requires major revisions and it’s recommended for reconsideration after major revision. Detailed comments are provided below.
- The reference list contains relatively few publications from the past three years, indicating an incomplete survey of recent advances. A more thorough literature review incorporating up-to-date studies is needed to better situate this work within the current state of the field.
- Lines 30–31: Describing LES as “the most novel tool” for resolving three-dimensional pollutant distributions in urban environments is inaccurate-- LES has been widely used in urban atmospheric dispersion modelling for well over a decade. And the reference (Salim et al., 2011) is also outdated. The authors should revise this claim and replace or supplement the reference with more recent literature.
- Lines 89–91: References show good agreement between PALM-SALSA and observations in prior studies, but does not validate the present simulation, which involves a different domain, configuration, and emission scenario (Kurppa et al., 2019; Du et al., 2024a). The lack of site-specific observational data for model evaluation is a notable weakness. The authors should either provide direct measurement-based validation for the current domain or explicitly acknowledge this limitation and discuss its implications for result reliability.
- Lines 176–178: A one-hour spin-up (7:00–8:00 UTC+2) is likely insufficient for the LES to reach a statistically steady turbulent state in a complex urban environment, and a one-hour main run is very short for deriving robust conclusions. The authors should justify the adequacy of the spin-up duration and discuss how the limited simulation period may affect the reliability and generalizability of their results.
- Lines 190-191: The claims made here are unsupported. Please add appropriate citations.
- Lines 218–220: The reported wind speed increases contain numerical errors. Based on the values given, the increases at 10 m and 20 m are approximately 33% and 78%, respectively — not 30% and 56% as stated. Additionally, Figure 4c cited in this passage does not appear in the manuscript. The inconsistent use of “Fig.” and “Figure” throughout the manuscript should also be standardized.
- Lines 260–262: The authors attribute a measurement campaign conducted in “January–February 2022” to Teinilä et al. (2019), which is a clear chronological inconsistency. The actual measurement period in the cited reference should be verified and the description corrected accordingly. And lines 279–280 present a similar issue, where the reported values appear inconsistent with the cited reference. The authors should recheck this paper.
- Lines 281-284: The comparison with Beddows and Harrison (2021) is inappropriate, as that study reports a 21% increase in particulate mass rather than PM5 concentration — these are distinct quantities and should not be treated as directly comparable. Additionally, Wang et al. (2021) find, based on WRF-CMAQ model, that full electrification could reduce PM2.5 concentrations by 30–70% across most regions of China, which stands in contrast to the 15% increase projected in the present study. The authors should address this inconsistency and provide a clearer mechanistic explanation for the divergence between their findings and those of Wang et al. (2021).
Wang, L., Chen, X., Zhang, Y., et al. (2021). Switching to electric vehicles can lead to significant reductions of PM2.5 and NO2across China. One Earth, 4(7), 1037-1048.
- Section 3.5: The authors argue that mildly stable conditions and shared meteorology across scenarios keep uncertainties small and comparable. This reasoning is not convincing. Resler et al. (2024) report model errors of 30–66% in pollutant concentrations even under weakly stable conditions. Furthermore, atmospheric stability nonlinearly modifies vertical mixing and local ventilation, meaning biases do not necessarily cancel in scenario comparisons. No sensitivity analysis is provided to support extending these conclusions to other periods such as the evening rush hour. These points must be addressed.
Technical Corrections
- Line 68: please introduce the PALM with its complete title at first use.
- Figure 3: The unit in the figure title (# m⁻² s⁻¹) appears incorrect. The authors should verify and correct the unit accordingly.
- Figure 8 and Figure 9: The PM5 unit in Figure 8 is incorrectly labelled, and the PN2.5 unit in Figure 9 is misplaced. Both should be carefully checked and corrected to ensure consistency with the text and other figures.
- Lines 413–416: A reference is duplicated in this section. Please remove the repeated entry.
- Lines 475–476: The reference listed here has since been formally published. Please update it to include the correct volume, issue, and page numbers or article number.
- Lines 485–486, 507–508, and 522–523: The formatting of these references is not correct. Please revise all affected entries accordingly.
Citation: https://doi.org/10.5194/egusphere-2026-341-RC2 -
RC3: 'Comment on egusphere-2026-341', Anonymous Referee #3, 26 Jun 2026
reply
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2026/egusphere-2026-341/egusphere-2026-341-RC3-supplement.pdf
Viewed
Total article views: 1,628 (including HTML, PDF, and XML)
Cumulative views and downloads
(calculated since 17 Mar 2026)
| HTML | XML | Total | Supplement | BibTeX | EndNote | |
|---|---|---|---|---|---|---|
| 1,061 | 503 | 64 | 1,628 | 119 | 53 | 69 |
- HTML: 1,061
- PDF: 503
- XML: 64
- Total: 1,628
- Supplement: 119
- BibTeX: 53
- EndNote: 69
Viewed (geographical distribution)
Total article views: 1,626 (including HTML, PDF, and XML)
Thereof 1,626 with geography defined
and 0 with unknown origin.
| Country | # | Views | % |
|---|
| Total: | 0 |
| HTML: | 0 |
| PDF: | 0 |
| XML: | 0 |
- 1
1
Latest update: 26 Jun 2026
Institute for Atmospheric and Earth System Research (INAR/Physics), Faculty of Science, University of Helsinki, Helsinki, 00014, Finland
School of Engineering and Computer Science, Bern University of Applied Sciences, Biel/Bienne, Switzerland
Xiaoyu Li
Institute for Atmospheric and Earth System Research (INAR/Physics), Faculty of Science, University of Helsinki, Helsinki, 00014, Finland
Sasu Karttunen
School of Engineering and Computer Science, Bern University of Applied Sciences, Biel/Bienne, Switzerland
Department of Geoscience and Remote Sensing, Delft University of Technology, Delft, The Netherlands
Riku Viri
Faculty of Built Environment, Tampere University, Tampere, Finland
Roy Harrison
Division of Environmental Health Risk Management, School of Geography, Earth Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
Jani Strömberg
Institute for Atmospheric and Earth System Research (INAR/Physics), Faculty of Science, University of Helsinki, Helsinki, 00014, Finland
Aino Kaltianen
Department of Meteorology, Stockholm University, Stockholm, Sweden
Matti Leinonen
Department of Computer Science, Faculty of Science, University of Helsinki, Helsinki, 00014, Finland
Laura Ruotsalainen
Division of Environmental Health Risk Management, School of Geography, Earth Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
Helsinki Institute of Sustainability Science (HELSUS), University of Helsinki, Helsinki, Finland
Leena Järvi
Institute for Atmospheric and Earth System Research (INAR/Physics), Faculty of Science, University of Helsinki, Helsinki, 00014, Finland
Helsinki Institute of Sustainability Science (HELSUS), University of Helsinki, Helsinki, Finland
Short summary
We studied how switching to electric cars affects air quality in a new Helsinki neighborhood. Using advanced computer models, we found that a full shift to electric vehicles by 2040 will cut the number of tiny harmful particles by 60 % because tailpipe exhaust is removed. However, the total weight of these particles will actually increase by 15 % due to heavier vehicles causing more tire and road wear. This shows that urban planners must look beyond just engines maintain urban air quality.
We studied how switching to electric cars affects air quality in a new Helsinki neighborhood....
The manuscript by Nahid Atashi et al., "Quantifying the impact ...", presents a detailed study of urban air-quality effects induced by the transition to battery electric vehicles. Three future transition scenarios have been designed and applied to a refurbished urban neighborhood in Helsinki. The study relies on large-eddy simulations with the PALM–SALSA model dynamically coupled to the MEPS weather prediction system.
I have a very positive impression after reading this study. Both the design and the methodology are well thought out and fully justified. The models used are state-of-the-art and have been validated in several independent studies. The manuscript is well written, logically sound, and—which is infrequent today—includes only the necessary information about the research challenge, the method, and the results. The limitations of the study are also clearly identified and reported.
Although some improvements could be made to the study design and the manuscript itself, I would refrain from trivializing them. The only change I would ask the authors to make is to add a subsection with standard vertical profiles of velocity, temperature, TKE, and diffusion coefficients from the PALM simulations for all three domains; Fig. S2 is not sufficient here. This will help to better understand the strengths and weaknesses of the reported simulations, particularly those discussed from line 330 onward.
Otherwise, I would recommend the manuscript for acceptance and publication.