Hygroscopicity of internally mixed aerosol particles containing benzoic acid and inorganic salts

► The hygroscopicity of benzoic acid (BA) particles is investigated. ► The reason of diameters change of BA particles with the relative humidity is discussed. ► The DRHs of NaCl/BA and (NH4)2SO4/BA mixed particles are lower than those of pure inorganics. ► The internal mixed BA hinders the hygroscopic growth of deliquescent inorganic droplets.