The sampling system consists of
low-pressure impactor (LPI), an isokinetic sampler probe, precut
cyclone (cutoff diameter is 10 mm), dilution system, and sample line
to the instruments. Among the studies, 13-stage electrical lowpressure
impactor (ELPI) was used by Yi et al. [3,26], and 8-stage
Andersen Cascade Impactor by Yue et al. from Tsinghua group [27–
29]; while 13-stage Dekati LPI (DLPI) was adopted by Sui et al. from
HUST group[30,31].