A GK2.05SH (KTL) cyclone sampler (BGI Inc., Waltham, MA) with a cut point of 2.5 m at an air flow of 3.5 l/min, which has been shown by other studies to have good agreement with the PQ200 (BGI Inc.) Federal Reference Method PM2.5 sampler (Yanosky and Macintosh, 2001; Majestic et al., 2008), was used to collect
PM2.5.