Table 1.

Comparisons of meteorological parameters and concentrations of trace gases and PM_2.5 and mixing ratios of VOCs during P1, P2, and P3.

Variables		P1	P2	P3	(P2-P1)/P1 × 100%	t-Test (p)
Meteorological parameters	WS, m/s	1.62	1.75	3.02	8%	0.031
	Temperature, °C	5.57	6.98	19.5	25%	<0.001
	RH, %	81.8	75	68.8	−8%	<0.001
	Pressure, hPa	102.4	102.2	101.1	0%	<0.001
	Visibility, km	6.23	9.89	14.8	59%	<0.001
Trace gases and PM2.5, μg/m3	PM2.5	65.0	42.28	35.9	−35%	<0.001
	CO	0.868	0.764	0.866	−12%	<0.001
	SO2	8.80	6.3	9.72	−28%	<0.001
	NO2	49.0	25.7	45.1	−48%	<0.001
	O3	30.7	59.2	84.9	92%	<0.001
	Ox	79.6	84.8	127	7%	<0.001
VOCs, ppb	VOCs	50.9	26.9	31.9	−47%	<0.001
	NMHCs	38.7	20.9	22.3	−46%	<0.001
	Alkanes	24.6	14.2	13.6	−42%	<0.001
	Alkenes	9.09	4.76	5.11	−48%	<0.001
	Aromatics	5.02	1.90	3.56	−62%	<0.001