未来能源研究所-空气净化器在学校的作用（英）

The Effect of Air Purifiers in SchoolsJacopo Bonan, Francesco Granella, Stefania Renna, Luis Sarmiento, and Massimo Tavoni Working Paper 25-17June 2025The Effect of Air Purifiers in Schools∗Jacopo Bonan1,2,3,*Francesco Granella1,2Stefania Renna1,2,5Luis Sarmiento1,2,4Massimo Tavoni1,2,5We randomize the installation of air purifiers across primary school classrooms toreduce children’s exposure to air pollution. The intervention reduces indoor PM2.5concentrations by 32% and decreases student absenteeism by 12.5%.Effects arelarger among students with higher pre-treatment absenteeism. The impact is greaterwhen outdoor air pollution is relatively low and diminishes as outdoor pollutionintensifies, consistent with non-linear marginal effects of air quality on health. Thetreatment students report fewer respiratory symptoms and exhibit greater awarenessof air quality. The cost per absence day avoided is approximately AC11, resulting ina conservative cost-benefit ratio of one-to-nine.JEL codes: C93, I21, Q53, Q51Keywords: Indoor air quality, air purifiers, school absences, randomized controlled trial1RFF-CMCC European Institute on Economics and the Environment (EIEE), Milan, Italy.2Centro Euro-Mediterraneo Sui Cambiamenti Climatici (CMCC), Lecce, Italy.3University of Brescia, Brescia, Italy.4Banco de M´exico, M´erida, Mexico.5Politecnico di Milano, Italy.*Corresponding author. E-mail: jacopo.bonan@cmcc.it∗This study was funded by the European Union - NextGenerationEU, Mission 4, Component 2, in the framework of theGRINS -Growing Resilient, INclusive and Sustainable project (GRINS PE00000018 – CUP C93C22005270001) andfrom PRIN 2020HKPNPL “DIGITA”. The views and opinions expressed are solely those of the authors and do notnecessarily reflect those of the European Union, nor can the European Union be held responsible for them. We arethankful to Luca Valentini and Giulio Spaggiari from NETCO for the fruitful collaboration.We thank the schooldirectors and the team of teachers who collaborated with us in the project implementation. This project benefitedfrom feedback from Michela Boldrini, Giovanna d’Adda, John Gomez-Mahecha, Wei Guo, Jacopo Lunghi, Beia Spiller,and participants at GLO-SITES 2024, Symposium on Advancing Sustainability Research with Experimental Methods,University of Padua, IAERE 2025, and EIEE Brown Bag seminar. The project was pre-registered on the AEA RCTRegistry (AEARCTR-0011960) and received ethical approval from Politecnico di Milano Institutional Review Board(code 18/2023).11. IntroductionAir pollution is a global health issue contributing to child mortality and morbidity worldwide(Institute for Health Metrics and Evaluation, 2019; Annesi-Maesano et al., 2021). High pollution-related morbidity increases school absences (Currie et al., 2009), negatively impacting learningoutcomes and educational activities (Gershenson et al., 2017; Aguilar-Gomez et al., 2022). Al-though various pollution-control measures have reduced average urban exposur