Indoor Source Apportionment and Health Risk Assessment of Inorganic PM 2.5 in a University Building in the UAE

Indoor air quality (IAQ) is a growing public health concern, especially in environments where individuals spend the majority of their time, such as homes, educational institutions, and office environments. This study investigates the elemental composition, chemical speciation, source apportionment, and health risks associated with indoor PM 2.5 in a university building in the United Arab Emirates over a 1‐year period. An indoor sampling campaign was conducted following international standards, and elemental analysis was performed using energy‐dispersive X‐ray fluorescence (EDXRF) spectroscopy. Crystallographic phases and compound identification were performed using X‐ray diffraction (XRD) and scanning electron microscopy with energy‐dispersive X‐ray spectroscopy (SEM/EDS), respectively. Positive Matrix Factorization (PMF v5.0) was applied to apportion pollution sources, while health risk assessments were conducted for trace element exposure based on methods from the US EPA and the Agency for Toxic Substances and Disease Registry (ATSDR). Key indoor PM 2.5 contributors included mineral and resuspended dust, sea salt, and anthropogenic sources such as heavy oil combustion, traffic, and secondary aerosols. The health risk assessment showed that all analyzed elements (Cr, Mn, Al, As, Cu, Ni, Pb, Zn, and Mg) had hazard quotient values below 1, indicating no noncarcinogenic risk, and the carcinogenic risk values for As, Cr, Ni, and Pb were below the ATSDR’s threshold value of 1 × 10 −6 . Multiple‐Path Particle Dosimetry modeling showed that approximately 75% of inhaled PM 2.5 deposits in the respiratory system, with younger individuals (18 years old) exhibiting slightly lower deposition. After 5 days of exposure, alveolar retention reached 0.072 mg in 21‐year‐olds and 0.066 mg in 18‐year‐olds, indicating potential for prolonged internal deposition. The findings underscore the importance of continuous monitoring and mitigation strategies to improve IAQ in densely occupied indoor environments.