Use of partial order in environmental pollution studies demonstrated by urban BTEX air pollution in 20 major cities worldwide Lars Carlsen a, ⁎, Rainer Bruggemann b , Bulat Kenessov c a Awareness Center, Linkøpingvej 35, Trekroner, DK-4000 Roskilde, Denmark b Leibniz - Institute of Freshwater Ecology and Inland Fisheries, Department Ecohydrology, Müggelseedamm 310, D-12587 Berlin, Germany c Al-Farabi Kazakh National University, Faculty of Chemistry and Chemical Technology, Center of Physical Chemical Methods of Research and Analysis, Almaty, Kazakhstan HIGHLIGHTS • Disclosure of the degree of BTEX air pol- lution in 20 major cities by partial order methodology • Ranking of the cities based on BTEX- pollutants simultaneously • Disclosure of ‘peculiar’ cities with re- spect to extreme values for one or more components • Influence of data uncertainty/noise on the mutual raking of the cities • Relationship between the degree of BTEX air pollution and the Gross Nation- al Income GRAPHICAL ABSTRACT abstract article info Article history: Received 22 March 2017 Received in revised form 31 July 2017 Accepted 3 August 2017 Available online xxxx Editor: D. Barcelo Urban air pollution with benzene, toluene, ethyl benzene and xylenes (BTEX) is a common phenomenon in major cities where the pollution mainly originates from traffic as well as from residential heating. An attempt to rank cities according to their BTEX air pollution is not necessarily straight forward as we are faced with several indi- vidual pollutants simultaneously. A typical procedure is based on aggregation of data for the single compounds, a process that not only hides important information but is also subject to compensation effects. The present study applies a series of partial ordering tools to circumvent the aggregation. Based on partial order- ing, most important indicators are disclosed, and an average ranking of the cities included in the study is derived. Since air pollution measurements are often subject to significant uncertainties, special attention has been given to the possible effect of uncertainty and/or data noise. Finally, the effect of introducing weight regimes is studied. In a concluding section the gross national income per person (GNI) is brought into play, demonstrating a positive correlation between BTEX air pollution and GNI. The results are discussed in terms of the ability/willingness to combat air pollution in the cities studied. The present study focuses on Almaty, the largest city in Kazakhstan and compares the data from Almaty to anoth- er 19 major cities around the world. It is found that the benzene for Almaty appears peculiar high. Overall Almaty appears ranked as the 8th most BTEX polluted city among the 20 cities included in the study. © 2017 Elsevier B.V. All rights reserved. Keywords: BTEX Urban air pollution Partial order Hasse diagram Data uncertainty GNI 1. Introduction The World Health Organization (WHO) estimates that 3.7 million people under the age of 60 died in 2012 as a result of outdoor air Science of the Total Environment 610–611 (2018) 234–243 ⁎ Corresponding author. E-mail address: LC@AwarenessCenter.dk (L. Carlsen). http://dx.doi.org/10.1016/j.scitotenv.2017.08.029 0048-9697/© 2017 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv