Citation: Nazzal, Y.; B˘ arbulescu, A.; Sharma, M.; Howari, F.; Naseem, M. Evaluating the Contamination by Indoor Dust in Dubai. Toxics 2023, 11, 933. https://doi.org/10.3390/ toxics11110933 Academic Editor: João Fernando Pereira Gomes Received: 29 October 2023 Revised: 13 November 2023 Accepted: 14 November 2023 Published: 17 November 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). toxics Article Evaluating the Contamination by Indoor Dust in Dubai Yousef Nazzal 1 , Alina Bărbulescu 2, * , Manish Sharma 1 , Fares Howari 3 and Muhammad Naseem 1 1 College of Natural and Health Sciences, Zayed University, Abu Dhabi P.O. Box 144534, United Arab Emirates; yousef.nazzal@zu.ac.ae (Y.N.); manish.sharma@zu.ac.ae (M.S.); muhammad.naseem@zu.ac.ae (M.N.) 2 Department of Civil Engineering, Transilvania University of Bras , ov, 5 Turnului Str., 900152 Brasov, Romania 3 College of Arts and Sciences, Fort Valley State University, Fort Valley, GA 31030, USA; Fares.Howari@fvsu.edu * Correspondence: alina.barbulescu@unitbv.ro Abstract: Nowadays, people spend most of their time indoors. Despite constantly cleaning these spaces, dust apparition cannot be avoided. Since dust can contain chemical elements that negatively impact people’s health, we propose the analysis of the metals from the indoor dust component collected in different locations in Dubai, UAE. Multivariate statistics (correlation matrix, clustering) and quality indicators (QI)—I geo , PI, EF, PLI, Nemerow—were used to assess the contamination level with different metals in the dust. We proposed two new QIs (CPI and AQI) and compared the results with those provided by the most used indices—PLI and Nemerow. It is shown that high concentrations of some elements (Ca in this case) can significantly increase the values of the Nemerow index, CPI, and AQI. In contrast, the existence of low concentrations leads to the decrement of the PLI. Keywords: contamination; dust; clustering; pollution index 1. Introduction Indoor dust is the settled particulate matter (PM) found on carpets, floors, surfaces, and other objects in an indoor space. Among other pollutants from indoor dust, heavy metals require extensive research due to their non-degradable properties, high toxicity, and adverse effects on humans [1,2]. The United States Environmental Protection Agency (USEPA) has raised the alarm about indoor air quality, considering it a significant concern because it tends to be more polluted than outdoor air. This concern has grown because people spend a significant portion of their time indoors, encompassing homes, workplaces, schools, public spaces like shops, restaurants, and vehicles, amounting to up to 90% of their daily activities [3]. Children, who spend most of their day at home, are particularly vulnerable to environmental stressors because their breathing zone is close to the floor, where residential dust tends to collect, exposing them to potential health risks [4–6]. Carbon dioxide, volatile organic compounds, biocontaminants, fungi, bacteria, and particulate matters are among the indoor air pollutants with damaging potential to human health listed by the European Federation of Allergy and Airway Diseases Patient Associ- ations in their document [7]. Dust intake rates for children are estimated to be between 30 and 140 mg/day, whereas adults consume 2–30 mg/day [8,9]. According to [10,11], indoor dust can be described as tiny particles (≤100 μm) that settle in indoor spaces. These particles can come from various sources situated inside and outside the building. Particles with diameters smaller than 10 μm (PM 10 ) can be inhaled, the coarse fractions being retained in the upper airways, and those particles with diameters less than 2.5 μm can reach the pulmonary system or enter the blood [12]. Particles with diameters from 1 μm to 20 μm are responsible for the apparition of asthma [13]. Tsubata et al. [14] indicate that dust particles with diameters less than 11 μm contain up to 90% of allergens. Research has indicated that indoor dust is a transporter for inorganic and organic contaminants, including heavy metals, pesticides, polychlorobiphenyls, and polycyclic Toxics 2023, 11, 933. https://doi.org/10.3390/toxics11110933 https://www.mdpi.com/journal/toxics