{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,7]],"date-time":"2026-04-07T16:29:58Z","timestamp":1775579398856,"version":"3.50.1"},"reference-count":52,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2022,7,14]],"date-time":"2022-07-14T00:00:00Z","timestamp":1657756800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"European Union","award":["2018-EU-IA-0095"],"award-info":[{"award-number":["2018-EU-IA-0095"]}]},{"name":"European Union","award":["SGS22\/047\/OHK1\/1T\/11"],"award-info":[{"award-number":["SGS22\/047\/OHK1\/1T\/11"]}]},{"name":"Grant Agency of the Czech Technical University in Prague","award":["2018-EU-IA-0095"],"award-info":[{"award-number":["2018-EU-IA-0095"]}]},{"name":"Grant Agency of the Czech Technical University in Prague","award":["SGS22\/047\/OHK1\/1T\/11"],"award-info":[{"award-number":["SGS22\/047\/OHK1\/1T\/11"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Air pollution is currently considered one of the most serious problems facing humans. Fine particulate matter with a diameter smaller than 2.5 micrometres (PM2.5) is a very harmful air pollutant that is linked with many diseases. In this study, we created a machine learning-based scheme to estimate PM2.5 using various open data such as satellite remote sensing, meteorological data, and land variables to increase the limited spatial coverage provided by ground-monitors. A space-time extremely randomised trees model was used to estimate PM2.5 concentrations over Europe, this model achieved good results with an out-of-sample cross-validated R2 of 0.69, RMSE of 5 \u03bcg\/m3, and MAE of 3.3 \u03bcg\/m3. The outcome of this study is a daily full coverage PM2.5 dataset with 1 km spatial resolution for the three-year period of 2018\u20132020. We found that air quality improved throughout the study period over all countries in Europe. In addition, we compared PM2.5 levels during the COVID-19 lockdown during the months March\u2013June with the average of the previous 4 months and the following 4 months. We found that this lockdown had a positive effect on air quality in most parts of the study area except for the United Kingdom, Ireland, north of France, and south of Italy. This is the first study that depends only on open data and covers the whole of Europe with high spatial and temporal resolutions. The reconstructed dataset will be published under free and open license and can be used in future air quality studies.<\/jats:p>","DOI":"10.3390\/rs14143392","type":"journal-article","created":{"date-parts":[[2022,7,15]],"date-time":"2022-07-15T01:57:11Z","timestamp":1657850231000},"page":"3392","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":22,"title":["Machine Learning-Based Approach Using Open Data to Estimate PM2.5 over Europe"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1660-9403","authenticated-orcid":false,"given":"Saleem","family":"Ibrahim","sequence":"first","affiliation":[{"name":"Department of Geomatics, Faculty of Civil Engineering, Czech Technical University in Prague, 166 29 Prague, Czech Republic"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6869-3542","authenticated-orcid":false,"given":"Martin","family":"Landa","sequence":"additional","affiliation":[{"name":"Department of Geomatics, Faculty of Civil Engineering, Czech Technical University in Prague, 166 29 Prague, Czech Republic"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2363-8002","authenticated-orcid":false,"given":"Ond\u0159ej","family":"Pe\u0161ek","sequence":"additional","affiliation":[{"name":"Department of Geomatics, Faculty of Civil Engineering, Czech Technical University in Prague, 166 29 Prague, Czech Republic"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4396-0477","authenticated-orcid":false,"given":"Luk\u00e1\u0161","family":"Brodsk\u00fd","sequence":"additional","affiliation":[{"name":"Department of Applied Geoinformatics and Cartography, Faculty of Science, Charles University, 128 43 Prague, Czech Republic"}]},{"given":"Lena","family":"Halounov\u00e1","sequence":"additional","affiliation":[{"name":"Department of Geomatics, Faculty of Civil Engineering, Czech Technical University in Prague, 166 29 Prague, Czech Republic"}]}],"member":"1968","published-online":{"date-parts":[[2022,7,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"9101","DOI":"10.3390\/ijerph110909101","article-title":"Fast Inverse Distance Weighting-Based Spatiotemporal Interpolation: A Web-Based Application of Interpolating Daily Fine Particulate Matter PM2.5 in the Contiguous U.S. Using Parallel Programming and k-d Tree","volume":"11","author":"Li","year":"2014","journal-title":"Int. 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