Table 4. The indoor and outdoor VOCs and HCHO levels and environmental factors by season (μg/m³).

Season		TVOC		Benzene		Toluene		Ethylbenzene		m.p-Xylene		Styrene		o-Xylene		HCHO		Temp (°C)	Relative humidity (%)
		N	GM ± GSD	N	GM ± GSD	N	GM ± GSD	N	GM ± GSD	N	GM ± GSD	N	GM ± GSD	N	GM ± GSD	N	GM ± GSD
January (winter)	Indoor	164	230.9 ± 2.1	165	4.1 ± 0.4	161	26.3 ± 1.3	163	4.5 ± 0.5	161	7.6 ± 0.7	165	2.9 ± 0.3	161	2.4 ± 0.3	178	20.0 ± 1.0	23.7	65.4
	Outdoor	49	127.2 ± 1.9	50	2.9 ± 1.7	50	18.5 ± 1.2	50	2.4 ± 0.2	50	4.1 ± 0.4	50	1.6 ± 0.2	50	1.1 ± 0.1	52	7.0 ± 0.6	1.1	63.1
	p-value		<0.01		<0.01		<0.01		<0.01		<0.01		<0.01		<0.01		<0.01	-	-
April (spring)	Indoor	158	238.4 ± 2.0	158	2.9 ± 0.4	157	26.3 ± 1.2	158	4.9 ± 0.4	158	9.1 ± 0.6	158	4.0 ± 0.3	158	3.0 ± 0.2	172	19.0 ± 0.9	24.2	66.8
	Outdoor	43	166.0 ± 2.0	43	2.9 ± 1.8	43	18.1 ± 1.1	43	3.9 ± 0.4	43	6.8 ± 0.7	43	3.5 ± 0.4	43	1.7 ± 0.2	51	8.3 ± 0.7	8.2	73.2
	p-value		<0.01		0.89		<0.01		< 0.01		<0.01		0.02		<0.01		<0.01	-	-
July (summer)	Indoor	161	311.1 ± 2.2	165	5.9 ± 0.5	160	25.5 ± 1.3	162	4.3 ± 0.4	163	7.2 ± 0.7	157	5.4 ± 0.5	163	2.6 ± 0.2	166	26.5 ± 1.1	26.3	74.6
	Outdoor	21	222.8 ± 2.1	24	5.2 ± 2.0	23	25.2 ± 1.4	24	3.6 ± 0.3	23	6.3 ± 0.6	22	4.5 ± 0.3	24	2.2 ± 0.1	37	13.8 ± 0.8	23.4	82.1
	p-value		<0.01		0.03		0.33		0.02		<0.01		<0.01		<0.01		<0.01	-	-
October (autumn)	Indoor	144	244.5 ± 1.9	143	4.4 ± 0.4	143	29.9 ± 1.3	138	5.8 ± 0.6	142	9.2 ± 0.8	142	2.3 ± 0.2	141	2.9 ± 0.4	169	22.5 ± 1.0	24.7	69.4
	Outdoor	45	145.9 ± 1.8	45	4.2 ± 1.8	42	25.5 ± 1.3	42	3.6 ± 0.5	43	5.2 ± 0.7	43	1.4 ± 0.1	43	1.5 ± 0.2	54	9.8 ± 0.8	18.6	72.5
	p-value		<0.01		0.26		<0.01		<0.01		<0.01		<0.01		<0.01		<0.01	-	-