{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,24]],"date-time":"2026-06-24T05:19:45Z","timestamp":1782278385218,"version":"3.54.5"},"reference-count":38,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2018,1,23]],"date-time":"2018-01-23T00:00:00Z","timestamp":1516665600000},"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>The increasing applications of low-cost air sensors promises more convenient and cost-effective systems for air monitoring in many places and under many conditions. However, the data quality from such systems has not been fully characterized and may not meet user expectations in research and regulatory uses, or for use in citizen science. In our study, electrochemical sensors (Alphasense B4 series) for carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO2), and oxidants (Ox) were evaluated under controlled laboratory conditions to identify the influencing factors and quantify their relation with sensor outputs. Based on the laboratory tests, we developed different correction methods to compensate for the impact of ambient conditions. Further, the sensors were assembled into a monitoring system and tested in ambient conditions in Hong Kong side-by-side with regulatory reference monitors, and data from these tests were used to evaluate the performance of the models, to refine them, and validate their applicability in variable ambient conditions in the field. The more comprehensive correction models demonstrated enhanced performance when compared with uncorrected data. One over-arching observation of this study is that the low-cost sensors may promise excellent sensitivity and performance, but it is essential for users to understand and account for several key factors that may strongly affect the nature of sensor data. In this paper, we also evaluated factors of multi-month stability, temperature, and humidity, and considered the interaction of oxidant gases NO2 and ozone on a newly introduced oxidant sensor.<\/jats:p>","DOI":"10.3390\/s18020059","type":"journal-article","created":{"date-parts":[[2018,1,23]],"date-time":"2018-01-23T13:06:51Z","timestamp":1516712811000},"page":"59","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":181,"title":["Impact Analysis of Temperature and Humidity Conditions on Electrochemical Sensor Response in Ambient Air Quality Monitoring"],"prefix":"10.3390","volume":"18","author":[{"given":"Peng","family":"Wei","sequence":"first","affiliation":[{"name":"School of Energy and Environment, City University of Hong Kong, Tat Avenue, Kowloon, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhi","family":"Ning","sequence":"additional","affiliation":[{"name":"School of Energy and Environment, City University of Hong Kong, Tat Avenue, Kowloon, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sheng","family":"Ye","sequence":"additional","affiliation":[{"name":"School of Energy and Environment, City University of Hong Kong, Tat Avenue, Kowloon, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Li","family":"Sun","sequence":"additional","affiliation":[{"name":"School of Energy and Environment, City University of Hong Kong, Tat Avenue, Kowloon, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fenhuan","family":"Yang","sequence":"additional","affiliation":[{"name":"School of Energy and Environment, City University of Hong Kong, Tat Avenue, Kowloon, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ka","family":"Wong","sequence":"additional","affiliation":[{"name":"School of Energy and Environment, City University of Hong Kong, Tat Avenue, Kowloon, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dane","family":"Westerdahl","sequence":"additional","affiliation":[{"name":"School of Energy and Environment, City University of Hong Kong, Tat Avenue, Kowloon, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Peter","family":"Louie","sequence":"additional","affiliation":[{"name":"Environmental Protection Department, the Government of the Hong Kong Special Administration Region, 33\/F Revenue Tower, 5 Gloucester Road, Wan Chai, Hong Kong, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2018,1,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1132","DOI":"10.1001\/jama.287.9.1132","article-title":"Lung cancer, cardiopulmonary mortality, and long-term exposure to fine particulate air pollution","volume":"287","author":"Pope","year":"2002","journal-title":"JAMA"},{"key":"ref_2","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":"Lance"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"949","DOI":"10.1016\/S1352-2310(01)00486-1","article-title":"Chemical characterization and source identification\/apportionment of fine and coarse air particles in Thessaloniki, Greece","volume":"36","author":"Manoli","year":"2002","journal-title":"Atmos. Environ."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Volkamer, R., Jimenez, J.L., San Martini, F., Dzepina, K., Zhang, Q., Salcedo, D., Molina, L.T., Worsnop, D.R., and Molina, M.J. (2006). Secondary organic aerosol formation from anthropogenic air pollution: Rapid and higher than expected. Geophys. Res. Lett., 33.","DOI":"10.1029\/2006GL026899"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1537","DOI":"10.1016\/S1352-2310(00)00551-3","article-title":"UCL discovery\u2014The transport sector as a source of air pollution","volume":"35","author":"Colvile","year":"2001","journal-title":"Atmos. Environ."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Hedley, A.J., McGhee, S.M., Barron, B., Chau, P., Chau, J., Thach, T.Q., Wong, T.W., Loh, C., and Wong, C.M. (2008). Air pollution: Costs and paths to a solution in Hong Kong\u2014Understanding the connections among visibility, air pollution, and health costs in pursuit of accountability, environmental justice, and health protection. J. Toxicol. Environ. Health A.","DOI":"10.1080\/15287390801997476"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Zhong, L., Louie, P.K.K., Zheng, J., Yuan, Z., Yue, D., Ho, J.W.K., and Lau, A.K.H. (2013). Science-policy interplay: Air quality management in the Pearl River Delta region and Hong Kong. Atmos. Environ.","DOI":"10.1016\/j.atmosenv.2013.03.012"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Clemitshaw, K. (2004). A Review of Instrumentation and Measurement Techniques for Ground-Based and Airborne Field Studies of Gas-Phase Tropospheric Chemistry. Crit. Rev. Environ. Sci. Technol.","DOI":"10.1080\/10643380490265117"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Heard, D.E. (2007). Analytical Techniques for Atmospheric Measurement, Wiley.","DOI":"10.1002\/9780470988510"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Piedrahita, R., Xiang, Y., Masson, N., Ortega, J., Collier, A., Jiang, Y., Li, K., Dick, R.P., Lv, Q., Hannigan, M., and Shang, L. (2014). The next generation of low-cost personal air quality sensors for quantitative exposure monitoring. Atmos. Meas. Tech.","DOI":"10.5194\/amtd-7-2425-2014"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"199","DOI":"10.1016\/j.envint.2014.11.019","article-title":"The rise of low-cost sensing for managing air pollution in cities","volume":"75","author":"Kumar","year":"2015","journal-title":"Environ. Int."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"31392","DOI":"10.3390\/s151229859","article-title":"A Survey of Wireless Sensor Network Based Air Pollution Monitoring Systems","volume":"15","author":"Yi","year":"2015","journal-title":"Sensors"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"5281","DOI":"10.5194\/amt-9-5281-2016","article-title":"Community Air Sensor Network (CAIRSENSE) project: Evaluation of low-cost sensor performance in a suburban environment in the southeastern United States","volume":"9","author":"Jiao","year":"2016","journal-title":"Atmos. Meas. Tech. Discuss."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"249","DOI":"10.1016\/j.snb.2015.03.031","article-title":"Field calibration of a cluster of low-cost available sensors for air quality monitoring. Part A: Ozone and nitrogen dioxide","volume":"215","author":"Spinelle","year":"2015","journal-title":"Sens. Actuators B Chem."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Spinelle, L., Gerboles, M., Villani, M.G., Aleixandre, M., and Bonavitacola, F. (2017). Field calibration of a cluster of low-cost commercially available sensors for air quality monitoring. Part B: NO, CO and CO2. Sens. Actuators B Chem.","DOI":"10.1016\/j.snb.2016.07.036"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Kim, J.Y., Chu, C.H., and Shin, S.M. (2014). ISSAQ: An Integrated Sensing Systems for Real-Time Indoor Air Quality Monitoring. IEEE Sens. J.","DOI":"10.1109\/ICISA.2014.6847385"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Snyder, E.G., Watkins, T.H., Solomon, P.A., Thoma, E.D., Williams, R.W., Hagler, G.S.W., Shelow, D., Hindin, D.A., Kilaru, V.J., and Preuss, P.W. (2013). The changing paradigm of air pollution monitoring. Environ. Sci. Technol.","DOI":"10.1021\/es4022602"},{"key":"ref_18","unstructured":"Aleixandre, M., and Gerboles, M. (2012). Review of small commercial sensors for indicative monitoring of ambient gas. Chem. Eng. Trans., 30."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Whitenett, G., Stewart, G., Atherton, K., Culshaw, B., and Johnstone, W. (2003). Optical fibre instrumentation for environmental monitoring applications. J. Opt. A Pure Appl. Opt.","DOI":"10.1088\/1464-4258\/5\/5\/355"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"5469","DOI":"10.3390\/s100605469","article-title":"Metal oxide semi-conductor gas sensors in environmental monitoring","volume":"10","author":"Fine","year":"2010","journal-title":"Sensors"},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Mead, M.I., Popoola, O.A.M., Stewart, G.B., Landshoff, P., Calleja, M., Hayes, M., Baldovi, J.J., McLeod, M.W., Hodgson, T.F., and Dicks, J. (2013). The use of electrochemical sensors for monitoring urban air quality in low-cost, high-density networks. Atmos. Environ.","DOI":"10.1016\/j.atmosenv.2012.11.060"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Lin, C., Gillespie, J., Schuder, M.D., Duberstein, W., Beverland, I.J., and Heal, M.R. (2015). Evaluation and calibration of Aeroqual series 500 portable gas sensors for accurate measurement of ambient ozone and nitrogen dioxide. Atmos. Environ.","DOI":"10.1016\/j.atmosenv.2014.11.002"},{"key":"ref_23","unstructured":"(2018, January 02). EuNetAir. Available online: http:\/\/www.eunetair.it\/."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"246","DOI":"10.1016\/j.atmosenv.2016.09.050","article-title":"Assessment of air quality microsensors versus reference methods: The EuNetAir joint exercise","volume":"147","author":"Borrego","year":"2016","journal-title":"Atmos. Environ."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Heimann, I., Bright, V.B., McLeod, M.W., Mead, M.I., Popoola, O.A.M., Stewart, G.B., and Jones, R.L. (2015). Source attribution of air pollution by spatial scale separation using high spatial density networks of low cost air quality sensors. Atmos. Environ.","DOI":"10.1016\/j.atmosenv.2015.04.057"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"370","DOI":"10.1016\/j.uclim.2014.08.002","article-title":"Mobile technologies and services for environmental monitoring: The Citi-Sense-MOB approach","volume":"14","author":"Castell","year":"2015","journal-title":"Urban Clim."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Roberts, T.J., Braban, C.F., Oppenheimer, C., Martin, R.S., Freshwater, R.A., Dawson, D.H., Griffiths, P.T., Cox, R.A., Saffell, J.R., and Jones, R.L. (2012). Electrochemical sensing of volcanic gases. Chem. Geol.","DOI":"10.1016\/j.chemgeo.2012.08.027"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Roberts, T.J., Saffell, J.R., Oppenheimer, C., and Lurton, T. (2014). Electrochemical sensors applied to pollution monitoring: Measurement error and gas ratio bias\u2014A volcano plume case study. J. Volcanol. Geotherm. Res.","DOI":"10.1016\/j.jvolgeores.2014.02.023"},{"key":"ref_29","unstructured":"(2018, January 02). Alphasense. Available online: http:\/\/www.alphasense.com\/WEB1213\/wp-content\/uploads\/2013\/07\/AAN_104.pdf."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Dai, H., Gong, L., Xu, G., Zhang, S., Lu, S., Jiang, Y., Lin, Y., Guo, L., and Chen, G. (2013). An electrochemical sensing platform structured with carbon nanohorns for detecting some food borne contaminants. Electrochim. Acta.","DOI":"10.1016\/j.electacta.2013.08.047"},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Hitchman, M.L., Cade, N.J., Kim, G.T., and Hedley, N.J.M. (1997). Study of the Factors Affecting Mass Transport in Electrochemical Gas Sensors. Analyst.","DOI":"10.1039\/a703644b"},{"key":"ref_32","unstructured":"White, R.M., Paprotny, I., Doering, F., Cascio, W.E., Solomon, P.A., and Gundel, L.A. (2012). EM: Air and Waste Management Association\u2019s Magazine for Environmental Managers, Air & Waste Management Association."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Vergara, A., Vembu, S., Ayhan, T., Ryan, M.A., Homer, M.L., and Huerta, R. (2012). Chemical gas sensor drift compensation using classifier ensembles. Sens. Actuators B Chem.","DOI":"10.1145\/2003653.2003655"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Sun, L., Wong, K.C., Wei, P., Ye, S., Huang, H., Yang, F., Westerdahl, D., Louie, P.K.K., Luk, C.W.Y., and Ning, Z. (2016). Development and application of a next generation air sensor network for the Hong Kong marathon 2015 air quality monitoring. Sensors.","DOI":"10.3390\/s16020211"},{"key":"ref_35","unstructured":"Spinelle, L., Aleixandre, M., and Gerboles, M. (2013). Protocol of Evaluation and Calibration of Low-Cost Gas Sensors for the Monitoring of Air Pollution, Publications Office of the European Union."},{"key":"ref_36","unstructured":"Williams, R., Conner, T., and Clements, A. (2017). Performance Evaluation of the United Nations Environment Programme Air Quality Monitoring Unit."},{"key":"ref_37","unstructured":"(2018, January 02). Alphasense. Available online: http:\/\/www.alphasense.com\/WEB1213\/wp-content\/uploads\/2013\/07\/AAN_109\u201302.pdf."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1291","DOI":"10.1021\/acssensors.6b00603","article-title":"Differentiating NO2 and O3 at Low Cost Air Quality Amperometric Gas Sensors","volume":"1","author":"Hossain","year":"2016","journal-title":"ACS Sens."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/2\/59\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T14:52:13Z","timestamp":1760194333000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/2\/59"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,1,23]]},"references-count":38,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2018,2]]}},"alternative-id":["s18020059"],"URL":"https:\/\/doi.org\/10.3390\/s18020059","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018,1,23]]}}}