Published December 2025 | Version Published
Journal Article Open

Interaction between climate factors and air quality in three Norwegian cities: A machine learning analysis

  • 1. ROR icon California Institute of Technology
  • 2. ROR icon University of Cambridge

Abstract

This study examines the interaction between climate factors and air quality in three Norwegian cities, addressing the gap where policymakers often analyze air quality and climate change in isolation. We investigate the association of specific climate variables on air pollution by comparing traditional regression models with machine learning techniques, including k-means clustering, hierarchical clustering, random forest, and recursive feature elimination. The models used are based on Europe's standard environmental policy frameworks, and the analysis draws on a decade's worth of daily data on traffic, weather, and air pollution from three major cities in Norway (2009–2018). Our findings highlight a strong correlation between Heating Degree Days (HDD) and elevated levels of pollutants like PM 2.5 and NO x , indicating that increased heating demand and traffic volume contribute significantly to worsening air quality. This research provides valuable insights into the seasonal dynamics of air pollution and offers a robust data-driven framework to help policymakers develop more effective and integrated urban climate and air quality policies. The research emphasizes the necessity of accounting for the interplay between climate change and air quality in the development of strategies to mitigate the health hazards linked to air pollution.

Copyright and License

© 2025 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Acknowledgement

We thank Zongyi Li from Caltech for providing us with invaluable advice.

Funding

CC and RMA acknowledge funding support from the Ronald and Maxine Linde Center for Science, Society, and Policy (LCSSP). RD acknowledges funding support from Cambridge Arts, Humanities and Social Science (AHSS) Research Grants 2023-24.

Contributions

Cong Cao: Writing – review & editing, Writing – original draft, Visualization, Methodology, Data analysis, Data curation, Conceptualization. Ramit Debnath: Writing – review & editing, Resources, Project administration, Conceptualization. R. Michael Alvarez: Writing – review & editing, Resources, Supervision, Project administration, Funding acquisition, Conceptualization.

Data Availability

The traffic flow, air pollutants, and meteorological data used in this work are publicly available and freely available from the Norwegian Public Road Administration, Statens Vegvesen (SVV), Norwegian Institute for Air Research (NILU), and the Norwegian Meteorological Institute (MET). The descriptive statistics for this data can be located in section 2.
The code is made available from Github repository.

Supplemental Material

Supplementary data (DOCX)

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Additional details

Funding

California Institute of Technology
Ronald and Maxine Linde Center -
University of Cambridge
Cambridge Arts, Humanities and Social Science (AHSS) 2023-24

Dates

Accepted
2025-08-29
Available
2025-09-15
Available online
Available
2025-10-15
Version of record

Caltech Custom Metadata

Caltech groups
Division of the Humanities and Social Sciences (HSS)
Publication Status
Published