{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T23:29:38Z","timestamp":1791329378342,"version":"4.3.1"},"reference-count":74,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2022,6,6]],"date-time":"2022-06-06T00:00:00Z","timestamp":1654473600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000780","name":"HPC and BigData Technologies for Global Systems (HiDALGO)","doi-asserted-by":"publisher","award":["824115"],"award-info":[{"award-number":["824115"]}],"id":[{"id":"10.13039\/501100000780","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100000780","name":"HPC and BigData Technologies for Global Systems (HiDALGO)","doi-asserted-by":"publisher","award":["881844"],"award-info":[{"award-number":["881844"]}],"id":[{"id":"10.13039\/501100000780","id-type":"DOI","asserted-by":"publisher"}]},{"name":"FFG-COMET-K1 Center \u201cPro\u00b2Future\u201d","award":["824115"],"award-info":[{"award-number":["824115"]}]},{"name":"FFG-COMET-K1 Center \u201cPro\u00b2Future\u201d","award":["881844"],"award-info":[{"award-number":["881844"]}]},{"DOI":"10.13039\/501100004955","name":"Swiss Federal Office for the Environment (FOEN)","doi-asserted-by":"publisher","award":["824115"],"award-info":[{"award-number":["824115"]}],"id":[{"id":"10.13039\/501100004955","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004955","name":"Swiss Federal Office for the Environment (FOEN)","doi-asserted-by":"publisher","award":["881844"],"award-info":[{"award-number":["881844"]}],"id":[{"id":"10.13039\/501100004955","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJERPH"],"abstract":"<jats:p>In this paper, the authors investigated changes in mass concentrations of particulate matter (PM) during the Coronavirus Disease of 2019 (COVID-19) lockdown. Daily samples of PM1, PM2.5 and PM10 fractions were measured at an urban background sampling site in Zagreb, Croatia from 2009 to late 2020. For the purpose of meteorological normalization, the mass concentrations were fed alongside meteorological and temporal data to Random Forest (RF) and LightGBM (LGB) models tuned by Bayesian optimization. The models\u2019 predictions were subsequently de-weathered by meteorological normalization using repeated random resampling of all predictive variables except the trend variable. Three pollution periods in 2020 were examined in detail: January and February, as pre-lockdown, the month of April as the lockdown period, as well as June and July as the \u201cnew normal\u201d. An evaluation using normalized mass concentrations of particulate matter and Analysis of variance (ANOVA) was conducted. The results showed that no significant differences were observed for PM1, PM2.5 and PM10 in April 2020\u2014compared to the same period in 2018 and 2019. No significant changes were observed for the \u201cnew normal\u201d as well. The results thus indicate that a reduction in mobility during COVID-19 lockdown in Zagreb, Croatia, did not significantly affect particulate matter concentration in the long-term..<\/jats:p>","DOI":"10.3390\/ijerph19116937","type":"journal-article","created":{"date-parts":[[2022,6,6]],"date-time":"2022-06-06T10:08:24Z","timestamp":1654510104000},"page":"6937","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":23,"title":["Machine Learning and Meteorological Normalization for Assessment of Particulate Matter Changes during the COVID-19 Lockdown in Zagreb, Croatia"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3541-9624","authenticated-orcid":false,"given":"Mario","family":"Lovri\u0107","sequence":"first","affiliation":[{"name":"Know-Center, Inffeldgasse 13, 8010 Graz, Austria"},{"name":"Institute for Anthropological Research, Gajeva 32, 10000 Zagreb, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mario","family":"Antunovi\u0107","sequence":"additional","affiliation":[{"name":"Ascalia d.o.o., Ulica Trate 16, 40000 \u010cakovec, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5289-9463","authenticated-orcid":false,"given":"Iva","family":"\u0160uni\u0107","sequence":"additional","affiliation":[{"name":"Institute for Anthropological Research, Gajeva 32, 10000 Zagreb, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Matej","family":"Vukovi\u0107","sequence":"additional","affiliation":[{"name":"Pro2Future GmbH, Inffeldgasse 25F, 8010 Graz, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Simonas","family":"Kecorius","sequence":"additional","affiliation":[{"name":"Institute of Epidemiology, Helmholtz Zentrum M\u00fcnchen, Ingolst\u00e4dter Landstr. 1, 85764 Neuherberg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mark","family":"Kr\u00f6ll","sequence":"additional","affiliation":[{"name":"Know-Center, Inffeldgasse 13, 8010 Graz, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ivan","family":"Be\u0161li\u0107","sequence":"additional","affiliation":[{"name":"Environmental Hygiene Unit, Institute for Medical Research and Occupational Health, Ksaverska cesta 2, 10000 Zagreb, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8441-1103","authenticated-orcid":false,"given":"Ranka","family":"Godec","sequence":"additional","affiliation":[{"name":"Environmental Hygiene Unit, Institute for Medical Research and Occupational Health, Ksaverska cesta 2, 10000 Zagreb, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gordana","family":"Pehnec","sequence":"additional","affiliation":[{"name":"Environmental Hygiene Unit, Institute for Medical Research and Occupational Health, Ksaverska cesta 2, 10000 Zagreb, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3257-743X","authenticated-orcid":false,"given":"Bernhard C.","family":"Geiger","sequence":"additional","affiliation":[{"name":"Know-Center, Inffeldgasse 13, 8010 Graz, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stuart K.","family":"Grange","sequence":"additional","affiliation":[{"name":"Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 D\u00fcbendorf, Switzerland"},{"name":"Wolfson Atmospheric Chemistry Laboratories, Department of Chemistry, University of York, York YO10 5DD, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6641-106X","authenticated-orcid":false,"given":"Iva","family":"\u0160imi\u0107","sequence":"additional","affiliation":[{"name":"Environmental Hygiene Unit, Institute for Medical Research and Occupational Health, Ksaverska cesta 2, 10000 Zagreb, Croatia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,6,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"136","DOI":"10.1016\/j.envint.2014.10.005","article-title":"A review on the human health impact of airborne particulate matter","volume":"74","author":"Kim","year":"2015","journal-title":"Environ. 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