The study was undertaken to investigate deposition behaviors of various size-segregated particles and indoor air quality using dust accumulated on the air conditioner filter acting as a sink for PTEs and nanoparticles that can pose a significant health risk. However, the particulate matter size and chemical composition in AC dust and its relationship with PTEs remains uncertain. Current study aims to investigate the PTEs and nanoparticles composition of AC dust using different analytical approaches including ICP-MS, XRD, XPS, SEM/TEM along with EDS and Laser Diffraction particle size analyzer. The mean concentration of PTEs like Al, As, Cd, Cu, Li, Pb, Sb, Se, Sn, Ti, V and Zn exceeded the corresponding background value. Pb, As, Sn, Sb, Cd were categorizing under geoaccumulation index class IV. Most of the particles were found to be > 100 gm and it decreased significantly with increase in floor altitude. A significantly negative correlation was found between particles size and PTEs concentration showing a significant increase in PTEs content with decrease in particles size. The XPS results showed dominant peaks for TiO2, Ti-O-N, As2O3, Fe+3, Fe+2, Al-OH and Al2O3. Additionally, As, Pb, Si and Fe were dominant metallic nanoparticles identified using SEM/TEM along with EDS.