Pulsed corona discharge (PCD) is one of the most commonly used methods for particle charging. In this study, a mosquito coil smoke aerosol with a diameter smaller than 0.5 mu m was used to investigate the charging of fine particles using an electrical low-pressure impactor (ELPI). The average number of charges per particle increases as the particle diameter becomes larger. Orthogonal design and single-factor analysis were carried out to optimize the particle charging conditions. The factors range as follows: wire-wire distance, d(ww) = single one wire and three wires with a distance of 3-9 cm; wire-plate distance, d(wp) = 3-6 cm; impulse-peak voltage, V = 30-45 kV; and impulse frequency, f = 100-300 Hz. The results show that d(ww) is the dominant factor, and the optimal conditions are as follows: a) for diameter smaller than 0.04 mu m: d(wp) = 5 cm, d(ww) = 9 cm, V = 35 kV, and f = 300 Hz; b) for the size range of 0.04-0.2 mu m; d(wp) = 4 cm, d(ww) = 9 cm, V = 45 kV, and f = 300 Hz; c) for the size range of 0.2-0.48 mu m: d(wp) = 4 cm, d(ww) = 9 cm, V = 45 kV, and f = 100 Hz. Moreover, the particle charging is much more difficult for the particle with a diameter of 0.2 mu m than the others. (C) 2015 Elsevier B.V. All rights reserved.