Howlett-Downing, Chantelle MargaretBoman, JohanMolnar, PeterWichmann, Janine2026-03-162026-03-162026Chantelle Howlett-Downing, Johan Boman, Peter Molnár & Janine Wichmann (28 Feb 2026): DN-PMF as a Sensitivity Test for Conventional PMF (C-PMF) Source Apportionment in Three Cities in South Africa, 2017–2018, Environmental Forensics, DOI: 10.1080/15275922.2026.2628337.1527-5922 (print)1527-5930 (online)10.1080/15275922.2026.2628337http://hdl.handle.net/2263/109011Source apportionment through factorization is a common method for identifying sources of air pollution. Both PCA and DN-PMF have assumptions, strengths, and limitations. Assigning sources to factors is inherently subjective and can introduce bias. PCA for the number of sources, C-PMF and DN-PMF is performed on data from three cities which were sampled at the same time, 16 April 2017 to 18 April 2018. The DN-PMF was able to give seasonal information to support the source apportionment. Results of the PCA included 6 factors for Thohoyandou and Pretoria and 7 factors for Cape Town. At the two large city sites, the C-PMF presented a dominant coal emissions source (29% and 35.6%) yearly and a strong biomass source during winter (24% and 17%). The dominant yearly source shifted to vehicular emissions with the DN-PMF model in Pretoria and Cape Town (41% and 12%) and coal burning at Thohoyandou (33%). By considering the mixing layer and meteorological conditions the factors shifted while keeping the dominant Cl-Pb and Cu-Zn tracer combinations. HIGHLIGHTS DN-PMF is a valid sensitivity test for C-PMF by reducing subjective bias during the assigning of sources to factors.en© 2026 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (http://creativecommons.org/licenses/by-nc-nd/4.0/).Conventional positive matrix factorization (C-PMF)SourcesSensitivity studyFine particles (PM2.5)Dispersion-normalized positive matrix factorization (DN-PMF)Air pollutionParticulate matterArticle