{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,31]],"date-time":"2025-12-31T12:10:36Z","timestamp":1767183036397,"version":"build-2065373602"},"reference-count":50,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2021,7,13]],"date-time":"2021-07-13T00:00:00Z","timestamp":1626134400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100008723","name":"Universidad de C\u00e1diz","doi-asserted-by":"publisher","award":["In process"],"award-info":[{"award-number":["In process"]}],"id":[{"id":"10.13039\/501100008723","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Good air quality is essential for both human beings and the environment in general. The three most harmful air pollutants are nitrogen dioxide (NO2), ozone (O3) and particulate matter. Due to the high cost of monitoring stations, few examples of this type of infrastructure exist, and the use of low-cost sensors could help in air quality monitoring. The cost of metal-oxide sensors (MOS) is usually below EUR 10 and they maintain small dimensions, but their use in air quality monitoring is only valid through an exhaustive calibration process and subsequent precision analysis. We present an on-field calibration technique, based on the least squares method, to fit regression models for low-cost MOS sensors, one that has two main advantages: it can be easily applied by non-expert operators, and it can be used even with only a small amount of calibration data. In addition, the proposed method is adaptive, and the calibration can be refined as more data becomes available. We apply and evaluate the technique with a real dataset from a particular area in the south of Spain (Granada city). The evaluation results show that, despite the simplicity of the technique and the low quantity of data, the accuracy obtained with the low-cost MOS sensors is high enough to be used for air quality monitoring.<\/jats:p>","DOI":"10.3390\/s21144781","type":"journal-article","created":{"date-parts":[[2021,7,13]],"date-time":"2021-07-13T22:25:31Z","timestamp":1626215131000},"page":"4781","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":18,"title":["An Approximation for Metal-Oxide Sensor Calibration for Air Quality Monitoring Using Multivariable Statistical Analysis"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4293-2896","authenticated-orcid":false,"given":"Diego","family":"Sales-L\u00e9rida","sequence":"first","affiliation":[{"name":"Department of Automation Engineering, Electronics and Computer Architecture and Networks, University of C\u00e1diz, 11519 C\u00e1diz, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alfonso J.","family":"Bello","sequence":"additional","affiliation":[{"name":"Department of Statistic and Operations Research, University of C\u00e1diz, 11510 C\u00e1diz, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3763-8852","authenticated-orcid":false,"given":"Alberto","family":"S\u00e1nchez-Alzola","sequence":"additional","affiliation":[{"name":"Department of Statistic and Operations Research, University of C\u00e1diz, 11510 C\u00e1diz, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Pedro Manuel","family":"Mart\u00ednez-Jim\u00e9nez","sequence":"additional","affiliation":[{"name":"Department of Automation Engineering, Electronics and Computer Architecture and Networks, University of C\u00e1diz, 11519 C\u00e1diz, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,7,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1233","DOI":"10.1016\/S0140-6736(02)11274-8","article-title":"Air pollution and health","volume":"360","author":"Brunekreef","year":"2002","journal-title":"Lancet"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1923","DOI":"10.1016\/S0140-6736(18)32225-6","article-title":"Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990\u20132017: A systematic analysis for the Global Burden of Disease Study 2017","volume":"392","author":"Stanaway","year":"2018","journal-title":"Lancet"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1109\/LSENS.2017.2691677","article-title":"Investigation of an indoor air quality sensor for asthma management in children","volume":"1","author":"Jaimini","year":"2017","journal-title":"IEEE Sens. 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