Reduced Air Pollution during the Prevailing of COVID-19 Pandemic: Five Years Observation and Path Analysis in the Fenwei Plain, Northwest China

Table 2

Correlation among six air pollutants under different AQI value ranges; represents a significance level of 0.01 (P<0.01); represents a significance level of 0.05 (P<0.05).

	0–50						51–100
	PM2.5	PM10	SO2	CO	NO2	O3	PM2.5	PM10	SO2	CO	NO2	O3
AQI	0.366	0.490	0.183	−0.041	0.286	0.423	0.442	0.566	0.214	0.124	0.273	0.280
PM2.5	1	0.732	0.092	0.233	0.189	−1.37	1	0.635	0.279	0.388	0.330	−0.352
PM10		1	0.388	0.127	0.308	0.057		1	0.369	0.112	0.589	−0.245
SO2			1	0.357	0.190	0.142			1	0.636	0.330	−1.59
CO				1	−0.054	−0.58				1	0.29	−2.22
NO2					1	−0.247					1	−0.329
O3						1						1
	101–150						151–200
AQI	0.419	0.369	0.217	0.300	0.121	−0.120	0.341	0.347	0.91	0.171	0.120	-0.61
PM2.5	1	0.702	0.450	0.754	0.456	−0.757	1	0.49	0.203	0.611	0.234	−0.689
PM10		1	0.509	0.485	0.478	−0.619		1	0.346	0.256	0.272	−0.466
SO2			1	0.672	0.520	−0.406			1	0.665	0.358	−0.243
CO				1	0.455	−0.617				1	0.335	−0.537
NO2					1	−0.517					1	−0.286
O3						1						1
	201–250						>300
AQI	0.502	0.368	−0.010	0.073	0.140	−0.044	0.075	0.350	−0.27	−0.158	−0.215	−0.153
PM2.5	1	−0.083	0.061	0.247	0.302	−0.145	1	0.476	0.450	0.678	0.480	−0.474
PM10		1	0.287	0.178	0.346	−0.98		1	0.342	0.312	0.142	−0.292
SO2			1	0.552	0.500	−0.58			1	0.697	0.444	−0.175
CO				1	0.381	−0.281				1	0.616	−0.542
NO2					1	−0.238					1	−0.557
O3						1						1