To understand the characteristics of chemical components and diacids, oxoacids, and α-dicarbonyls in atmospheric aerosols at underground coal fire environment, we collected fine aerosols (PM2.5) in September, October, and December of 2018 from Wuhai, Inner Mongolia, North China, where the underground coal fire occurs severely. The datasets include the concentrations of PM2.5, and carbonaceous components (i.e., total carbon, TC; organic carbon, OC; Elemental carbon, EC; water-soluble OC, WSOC), inorganic ions, and diacids, oxoacids, and α-dicarbonyls and stable carbon isotope ratios of TC and diacids, oxoacids, and α-dicarbonyls in the PM2.5 samples (n =13).OC and EC were measured using OC/EC analyzer (Sunset Laboratory Inc., USA), based on thermal light reflectance following the IMPROVE protocol of the protective visual environment. The concentration of WSOC was measured using a TOC analyzer (TOC-L, 5000A, Shimadzu, Japan). Inorganic ions were measured using ion chromatography (Thermo Fisher, ICS 5000+). Diacids and related compounds were measured using a capillary gas chromatography (GC; Agilent 7890B). δ13C (‰; PDB) of TC was determined using an elemental analyzer (EA, Flash 2000HT) coupled with a stable isotope ratio mass spectrometer (IRMS, 253Plus), while the compound-specific δ13C (‰; PDB) of diacids, oxoacids, and α-dicarbonyls were determined using the GC-IRMS (Thermo Fisher, Mat253).

Missing values mean 'no detection'.Groups of measured parameters: - CC: Carbonaceous Components - II: Inorganic Ions - DI: Diacids - OX: Oxoacids - AD: α-Dicarbonyls - IR: Isotope ratios, given as isotopic signature versus standard Pee Dee Belemnite (PDB)