Chemical composition of indoor and outdoor PM in the eastern Arabian Peninsula.

Water-soluble and trace metal species in fine particulate matter (PM) were determined for indoor and outdoor environments in Doha, Qatar. During the study period, PM concentrations showed significant variability across several indoor locations ranging from 7.1 to 75.8 μg m, while the outdoor mass concentration range was 34.7-154.4 µg m. The indoor and outdoor PM levels did not exhibit statistically significant correlation, suggesting efficient building envelope protection against outdoor PM pollution. Rather than outdoor sources, human activities such as cooking, cleaning, and smoking were the most significant influence on chemical composition of indoor PM. NH concentration was insufficient to neutralize SO indoors and outdoors, indicating the predominant presence of NHHSO. The enrichment factors indicated that outdoor Fe, Mn, Co, Cr, and Ni in PM mostly originated from crustal sources. In contrast, the remaining outdoor trace metals (Cu, Zn, As, Cd, Pb, and V) were mainly derived from anthropogenic sources. The indoor/outdoor concentration ratios revealed significant indoor sources for NH and Cu. The crustal matter, water-soluble ions, and sea salt explained 42%, 21%, and 1% of the indoor PM mass, respectively. The same groups sequentially constituted 41%, 16%, and 1% of the outdoor PM mass.