Table 2.

Principal component analysis (PCA) for PM2.5 concentration and influencing factors in Xi’an, China.

	Component Matrix
	1	2	3	4
GDP	0.06	0.92	−0.08	−0.01
Population density	0.05	0.83	−0.37	0.02
Average temperature	0.94	−0.03	0.08	−0.14
Precipitation	0.65	0.00	−0.07	0.74
Wind speed	0.65	0.48	0.32	−0.22
SO2	−0.90	0.11	−0.05	0.08
NO2	−0.56	0.38	0.65	0.22
PM2.5	−0.89	0.08	−0.11	0.01
Cumulative %	45.35	69.39	78.06	86.39