Traffic-Emitted Amines Promote New Particle Formation at Roadsides
New particle formation (NPF) is a major source of atmospheric aerosol particles, significantly influencing particle number concentrations in urban environments. High condensation and coagulation sinks at highly trafficked roadside sites should suppress NPF due to the low survival probability of clusters and new particles, however, observations show that roadside NPF is frequent and intense. Here, we investigate NPF at an urban background and roadside site in Central Europe using simultaneous measurements of sulfuric acid, amines, highly oxygenated organic molecules (HOMs), and particle number size distributions. We demonstrate that sulfuric acid and amines, particularly traffic-derived C<sub>2</sub>-amines, are the primary participants in particle formation. C<sub>2</sub>-amine concentrations at the roadside are enhanced by over a factor of 4 relative to the background, overcoming the effect of enhanced coagulation and condensation sinks. Using machine learning we identify a further but uncertain enhancing role of HOMs. These findings reveal the critical role of traffic emissions in urban NPF.
Authors
- James Brean (ORCID: https://orcid.org/0000-0001-5430-6994)
- Alex Rowell (ORCID: https://orcid.org/0000-0001-6547-247X)
- Peter Mettke (ORCID: https://orcid.org/0000-0002-3236-9780)
- Siddharth Iyer (ORCID: https://orcid.org/0000-0001-5989-609X)
- Mira L. Pöhlker (ORCID: https://orcid.org/0000-0001-6852-0756)
- Roy M. Harrison (ORCID: https://orcid.org/0000-0002-2684-5226)
- David C. S. Beddows (ORCID: https://orcid.org/0000-0001-9277-2099)
- Patrick Rinke (ORCID: https://orcid.org/0000-0003-1898-723X)
- Alfred Wiedensohler (ORCID: https://orcid.org/0000-0001-8298-491X)
- Maik Merkel
- Avinash Kumar (ORCID: https://orcid.org/0000-0002-8148-9252)
- Miikka Dal Maso (ORCID: https://orcid.org/0000-0003-3040-3612)
- Zongbo Shi (ORCID: https://orcid.org/0000-0002-7157-543X)
- Shawon Barua (ORCID: https://orcid.org/0000-0003-1683-2242)
- Hilda Sandström (ORCID: https://orcid.org/0000-0001-7845-1088)
- Matti P. Rissanen (ORCID: https://orcid.org/0000-0003-0463-8098)
- Federica Bortolussi (ORCID: https://orcid.org/0009-0000-6661-1419)
- Kay Weinhold (ORCID: https://orcid.org/0009-0004-8316-0962)
- Alexandra Karppinen
Institutions
- University of Helsinki (FI)
- Tampere University (FI)
- King Abdulaziz University (SA)
- Leibniz Institute for Tropospheric Research (DE)
- Department of Chemistry and Earth Sciences (BY)
- National Institute of Meteorology (TN)
- Institute of Atomic Energy (PL)
- Environmental Earth Sciences (AU)
- Munich Center for Machine Learning
- Technical University of Munich (DE)
- University of Birmingham (GB)
- Aalto University (FI)
Publication Details
- Journal
- ACS ES&T Air
- Published
- 2025-07-16
- DOI
- https://doi.org/10.1021/acsestair.5c00119
- Citations
- 4
- Primary Topic
- Vehicle emissions and performance
- Type
- article
- Field-Weighted Citation Impact
- 2.73
Funders
- Academy of Finland
- Tampereen Yliopisto
- Natural Environment Research Council
- European Research Council