Characterization of summer organic and inorganic aerosols in Beijing, China with an Aerosol Chemical Speciation Monitor

► An Aerosol Chemical Speciation Monitor was first deployed in Beijing, China. ► High concentration of nitrate was frequently observed in summer in Beijing. ► PMF analysis of ACSM OA mass spectra identified OOA and HOA. ► High PM pollution is primarily associated with secondary organic/inorganic species.