Articles | Volume 4, issue 2
https://doi.org/10.5194/ar-4-547-2026
© 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/ar-4-547-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
04 Nov 2026
Research article |
| 04 Nov 2026
| 04 Nov 2026
Inhalation of small particles (PM2.5) in urban road tunnels and underground in Madrid (Spain) – a citizen science project
Medicine Department, Universidad Complutense Madrid, Calle Ocaña 120, 28047 Madrid, Spain
retired
Esther Gil Cid
Departamento de Matemática Aplicada, Universidad Nacional de Educación a Distancia (UNED), Calle Juan del Rosal, 12, 28040 Madrid, Spain
Luis Miguel Pozo Coronado
Departamento MATIC, ETSI Sistemas Informáticos, Campus Sur, Universidad Politécnica de Madrid, Calle Alan Turing s/n, 28031 Madrid, Spain
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Short summary
In road tunnels and the metro, there are small toxic airborne particles (PM2.5). In Madrid (Spain), there is no public information on PM2.5 in these infrastructures. One alternative is for citizen scientists to use validated low-cost sensors. Data from these sensors were compared with reference station data; their correlation was high. PM2.5 levels in Madrid’s tunnels and metro exceed 10 µg m–3 and are above the 2011 World Health Organization guideline.
In road tunnels and the metro, there are small toxic airborne particles (PM2.5). In Madrid...
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