{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,5]],"date-time":"2026-02-05T21:40:05Z","timestamp":1770327605907,"version":"3.49.0"},"reference-count":29,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2018,8,24]],"date-time":"2018-08-24T00:00:00Z","timestamp":1535068800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>There is increasing concern about the health impacts of ambient Particulate Matter (PM) exposure. Traditional monitoring networks, because of their sparseness, cannot provide sufficient spatial-temporal measurements characteristic of ambient PM. Recent studies have shown portable low-cost devices (e.g., optical particle counters, OPCs) can help address this issue; however, their application under ambient conditions can be affected by high relative humidity (RH) conditions. Here, we show how, by exploiting the measured particle size distribution information rather than PM as has been suggested elsewhere, a correction can be derived which not only significantly improves sensor performance but which also retains fundamental information on particle composition. A particle size distribution\u2013based correction algorithm, founded on    \u03ba   -K\u00f6hler theory, was developed to account for the influence of RH on sensor measurements. The application of the correction algorithm, which assumed physically reasonable    \u03ba    values, resulted in a significant improvement, with the overestimation of PM measurements reduced from a factor of ~5 before correction to 1.05 after correction. We conclude that a correction based on particle size distribution, rather than PM mass, is required to properly account for RH effects and enable low cost optical PM sensors to provide reliable ambient PM measurements.<\/jats:p>","DOI":"10.3390\/s18092790","type":"journal-article","created":{"date-parts":[[2018,8,24]],"date-time":"2018-08-24T11:13:45Z","timestamp":1535109225000},"page":"2790","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":137,"title":["Developing a Relative Humidity Correction for Low-Cost Sensors Measuring Ambient Particulate Matter"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7012-5552","authenticated-orcid":false,"given":"Andrea","family":"Di Antonio","sequence":"first","affiliation":[{"name":"Centre for Atmospheric Science, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2390-8436","authenticated-orcid":false,"given":"Olalekan A. M.","family":"Popoola","sequence":"additional","affiliation":[{"name":"Centre for Atmospheric Science, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK"}]},{"given":"Bin","family":"Ouyang","sequence":"additional","affiliation":[{"name":"Centre for Atmospheric Science, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK"}]},{"given":"John","family":"Saffell","sequence":"additional","affiliation":[{"name":"Alphasense Ltd., Sensor Technology House, 300 Avenue West, Skyline 120, Great Notley, Essex CM77 7AA, UK"}]},{"given":"Roderic L.","family":"Jones","sequence":"additional","affiliation":[{"name":"Centre for Atmospheric Science, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK"}]}],"member":"1968","published-online":{"date-parts":[[2018,8,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"941","DOI":"10.1289\/ehp.00108941","article-title":"Association of fine particulate matter from different sources with daily mortality in six U.S. cities","volume":"108","author":"Laden","year":"2000","journal-title":"Environ. 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