Table 6. Comparison of indoor VOCs and HCHO levels by construction year.

Name of pollutant	Construction year	N	GM1	AM ± SD2	p-value
TVOC	Before 2000	251	219.37	248.54±129.18	0.03
	After 2000	383	238.42	274.33±154.64
Benzene	Before 2000	237	3.55	4.59±2.54	0.36
	After 2000	353	3.71	4.81±2.91
Toluene	Before 2000	251	21.03	27.99±25.48	0.11
	After 2000	383	24.00	31.40±26.30
Ethylbenzene	Before 2000	249	3.94	4.88±4.26	0.03
	After 2000	377	4.61	5.58±3.90
m.p-Xylene	Before 2000	249	6.90	8.92±9.40	0.80
	After 2000	375	7.48	9.08±6.10
Styrene	Before 2000	216	3.20	3.85±2.99	0.01
	After 2000	350	3.98	5.07±5.28
o-Xylene	Before 2000	227	2.52	3.07±2.54	0.04
	After 2000	330	3.02	3.48±2.10
HCHO	Before 2000	267	18.33	20.49±10.20	<0.01
	After 2000	431	21.34	24.17±12.67

¹GM : Geometric mean;

²Arithmetic mean and Standard deviation