Ambient air pollutants and hospital visits for pneumonia: a case-crossover study in Qingdao, China

BMC Public Health

Table 6 Coherent matrix eigenvalues of multiple atmospheric pollutants model on lag2 days and relevant eigenvectors

	PC1	PC2	PC3	PC4
Eigenvalue	3.051	0.462	0.397	0.089
Proportion of variance	0.763	0.116	0.099	0.022
Cumulative proportion of variance	0.763	0.879	0.978	1.000
PM_2.5	0.535	−0.196	−0.398	−0.719
PM₁₀	0.529	−0.302	− 0.388	0.691
SO₂	0.457	0.885	0.055	0.068
NO₂	0.474	−0.294	0.829	−0.026

PC1: the first principal component; PC2: the second principal component; PC3: the third principal component; PC4: the fourth principal component

ISSN: 1471-2458