Reliability of reflectance measures in passive filters

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dc.contributor.authorAndre, Carmen Diva Saldiva
dc.contributor.authorAndre, Paulo Afonso
dc.contributor.authorRocha, Francisco Marcelo Monteiro [UNIFESP]
dc.contributor.authorSaldiva, Paulo Hilário Nascimento
dc.contributor.authorOliveira, Regiani Carvalho de
dc.contributor.authorSinger, Julio Motta
dc.contributor.institutionUniversidade de São Paulo (USP)
dc.contributor.institutionUniversidade Federal de São Paulo (UNIFESP)
dc.date.accessioned2016-01-24T14:37:37Z
dc.date.available2016-01-24T14:37:37Z
dc.date.issued2014-08-01
dc.description.abstractMeasurements of optical reflectance in passive filters impregnated with a reactive chemical solution may be transformed to ozone concentrations via a calibration curve and constitute a low cost alternative for environmental monitoring, mainly to estimate human exposure. Given the possibility of errors caused by exposure bias, it is common to consider sets of m filters exposed during a certain period to estimate the latent reflectance on n different sample occasions at a certain location. Mixed models with sample occasions as random effects are useful to analyze data obtained under such setups. the intra-class correlation coefficient of the mean of the m measurements is an indicator of the reliability of the latent reflectance estimates. Our objective is to determine m in order to obtain a pre-specified reliability of the estimates, taking possible outliers into account. To illustrate the procedure, we consider an experiment conducted at the Laboratory of Experimental Air Pollution, University of São Paulo, Brazil (LPAE/FMUSP), where sets of m = 3 filters were exposed during 7 days on n = 9 different occasions at a certain location. the results show that the reliability of the latent reflectance estimates for each occasion obtained under homoskedasticity is k(m) = 0.74. A residual analysis suggests that the within-occasion variance for two of the occasions should be different from the others. A refined model with two within-occasion variance components was considered, yielding k(m) = 0.56 for these occasions and k(m) = 0.87 for the remaining ones. To guarantee that all estimates have a reliability of at least 80% we require measurements on m = 10 filters on each occasion. (C) 2014 the Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).en
dc.description.affiliationUniv São Paulo, Inst Math & Stat, BR-05508 São Paulo, Brazil
dc.description.affiliationUniv São Paulo, Sch Med, BR-05508 São Paulo, Brazil
dc.description.affiliationUniversidade Federal de São Paulo, São Paulo, Brazil
dc.description.affiliationUnifespUniversidade Federal de São Paulo, EPPEN, Osasco, Brazil
dc.description.sourceWeb of Science
dc.description.sponsorshipINAIRA - Instituto Nacional de Avaliacao Integrada de Risco Ambiental
dc.description.sponsorshipConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
dc.description.sponsorshipFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.description.sponsorshipIDCNPq: 15/2008
dc.description.sponsorshipIDFAPESP: 2008/57717-6
dc.description.sponsorshipIDCNPq: 308613/2011-2
dc.format.extent178-181
dc.identifierhttp://dx.doi.org/10.1016/j.atmosenv.2014.04.023
dc.identifier.citationAtmospheric Environment. Oxford: Pergamon-Elsevier B.V., v. 92, p. 178-181, 2014.
dc.identifier.doi10.1016/j.atmosenv.2014.04.023
dc.identifier.fileWOS000338810800020.pdf
dc.identifier.issn1352-2310
dc.identifier.urihttp://repositorio.unifesp.br/handle/11600/38006
dc.identifier.wosWOS:000338810800020
dc.language.isoeng
dc.publisherElsevier B.V.
dc.relation.ispartofAtmospheric Environment
dc.rightsinfo:eu-repo/semantics/openAccess
dc.rights.licensehttp://www.elsevier.com/about/open-access/open-access-policies/article-posting-policy
dc.subjectPassive filtersen
dc.subjectAir pollutionen
dc.subjectReliabilityen
dc.subjectOutliersen
dc.subjectRandom effectsen
dc.titleReliability of reflectance measures in passive filtersen
dc.typeinfo:eu-repo/semantics/article
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