The environmental aerosols in major South Asian cities were characterized using Aerosol Robotic Network datasets. Various types of aerosols were identified and classified. Industrial urban/vehicle emissions and biomass burning carbonaceous aerosols dominated during the winter, whereas dust aerosols dominated during the summer and pre-monsoon seasons, respectively. Moreover, mixed aerosol types existed throughout the year. An attempt has been made to detect carbonaceous aerosol CO2 using Zn-decorated ZnO nanocages, which can be converted into CH3OH and H2O via the use of H2 molecules. The adsorption of Zn on the nanocage of ZnO reduced the band width to 2.18 eV from 4.05 eV, with an increase in the room temperature sensitivity and a sensing response of −49.38% and −91.9%, respectively. The emergence of intermediate states near the Fermi level narrowed the bandgap. The negative electronegativity and electron affinity suggest the polar nature, high reactivity, and softness of the Zn-decorated ZnO CO2 complexes. Furthermore, a minimal recovery time of 2.249 × 10−11 s was noticed at room temperature, highlighting the remarkable catalytic efficiency of the ZnO-Zn/CO2 system compared with that of previously published Ag-decorated ZnO nanocages. An increase in temperature has minimal effects on the sensing response, while the recovery time decreased notably. This research was conducted within the context of density functional theory.