Indoor PM2.5 and its chemical composition during a heavy haze-fog episode at Jinan, China

PM2.5 samples were collected in both a typical laboratory (indoors) and adjacent courtyard (outdoors) in Jinan, China from 12 January to 4 February 2013. The samples were analysed for 10 inorganic water-soluble ions, 14 elements and carbonaceous species to investigate their chemical characteristics and relationships with indoor and outdoor PM2.5 during a severe haze-fog (HF) episode and a normal (NHF) period. The average indoor and outdoor PM2.5 concentrations during the HF episode were 236 mu g/m(3) and 409 mu g/m(3), respectively, whereas the corresponding figures for the NHF period were 62 mu g/m(3) and 87 mu g/m(3). The predominant component was (NH4)(2)SO4, which accounted for 55.07% and 44.43% of the total measured species of indoor and outdoor PM2.5, respectively, in the HF episode, and 40.31% and 32.93%, respectively, in the NHF period. The indoor NH4NO3 level was significantly lower than the outdoor level due to volatility. The indoor and outdoor concentration ratios, infiltration rates, and indoor-generated concentration of PM2.5 and chemical compounds (SO42-, NO3- and EC) indicate that the aforementioned species had primarily outdoor sources, whereas NH4- and DC and all the measured elements appear to have indoor sources, Cu in particular. (C) 2014 Elsevier Ltd. All rights reserved.