The potable air sampler with a mini pump (SIBATA MP-Σ300) was applied for sampling air at the heights of
around 1.1 m from the ground, with a sampling rate of 1 L/min for 30 min. Air samples for testing HCHO and
acetaldehyde were contained in active gas tubes (SIBATA, DNPH active gas tube), and those for VOCs test were
collected in solid phase samplers (SIBATA, Charcoal tube standard). After finishing the sampling, the tubes were
tightly plugged and then sealed in the attached bag specially designed for preserving the active gas tube. Next,
HCHO and acetaldehyde were analyzed with the high performance liquid chromatography (HPLC) method
proposed by Japanese Standards Association [13], and VOCs were analyzed with the gas chromatography/mass
spectrometry (GC/MS) methods by Japanese Standards Association [14]. TVOCs' level was a sum of the
concentrations of identified VOCs, which were quantified with each calibration curve, and the concentrations of
unidentified VOCs calculated using the response factor of toluene from C6 to C16.