Articles | Volume 26, issue 9
https://doi.org/10.5194/acp-26-6521-2026
https://doi.org/10.5194/acp-26-6521-2026
Research article
 | 
15 May 2026
Research article |  | 15 May 2026

Ventilation and low pollution enhancing new particle formation in Milan, Italy

Myriam Agrò, Manuel Bettineschi, Silvia Melina, Diego Aliaga, Andrea Bergomi, Beatrice Biffi, Alessandro Bigi, Giancarlo Ciarelli, Cristina Colombi, Paola Fermo, Ivan Grigioni, Veli-Matti Kerminen, Markku Kulmala, Janne Lampilahti, Angela Marinoni, Celestine Oliewo, Juha Sulo, Gianluigi Valli, Roberta Vecchi, Tuukka Petäjä, Katrianne Lehtipalo, and Federico Bianchi

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Cited articles

Agrò, M.: Data of “Ventilation and low pollution enhancing new particle formation in Milan, Italy”, Zenodo, https://doi.org/10.5281/zenodo.18130252, 2026. 
Aliaga, D., Tuovinen, S., Zhang, T., Lampilahti, J., Li, X., Ahonen, L., Kokkonen, T., Nieminen, T., Hakala, S., Paasonen, P., Bianchi, F., Worsnop, D., Kerminen, V.-M., and Kulmala, M.: Nanoparticle ranking analysis: determining new particle formation (NPF) event occurrence and intensity based on the concentration spectrum of formed (sub-5 nm) particles, Aerosol Res., 1, 81–92, https://doi.org/10.5194/ar-1-81-2023, 2023. 
Bae, M.-S., Schwab, J. J., Hogrefe, O., Frank, B. P., Lala, G. G., and Demerjian, K. L.: Characteristics of size distributions at urban and rural locations in New York, Atmos. Chem. Phys., 10, 4521–4535, https://doi.org/10.5194/acp-10-4521-2010, 2010. 
Batchvarova, E. and Gryning, S.-E.: Applied model for the growth of the daytime mixed layer, Bound.-Layer Meteorol., 56, 261–274, https://doi.org/10.1007/BF00120423, 1991. 
Bettineschi, M., Vitali, B., Cholakian, A., Zardi, D., Bianchi, F., Sinclair, V., Mikkola, J., Cristofanelli, P., Marinoni, A., Mazzini, M., Heikkinen, L., Aurela, M., Paglione, M., Bessagnet, B., Tuccella, P., and Ciarelli, G.: Across land, sea, and mountains: sulphate aerosol sources and transport dynamics over the northern Apennines, Environ. Sci. Atmos., 5, 1023–1034, https://doi.org/10.1039/D5EA00035A, 2025. 
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This study investigates new particle formation (NPF) in Milan, the most populated city in the Po Valley (Italy), using one year of particle number size distribution data (1.2–480 nm). NPF is enhanced under cleaner air conditions with lower pollution, reduced condensation sink, stronger ventilation, and stronger northwesterly winds (e.g., Foehn events). In contrast, longer air mass residence time in the Po Valley and higher air mass exposure to anthropogenic emissions suppress it.
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