变量

lnSO₂

直接效应

间接效应

总效应

lnEC

1.0238^***

(6.2317)

0.5933

(1.4464)

1.6171^***

(3.8137)

lnPOP

−1.0752^*

(−2.3871)

−0.8575

(−0.9312)

−1.9327^**

(−2.4616)

lnPGDP

−0.1041

(−0.6406)

−0.1230

(−0.4508)

−0.2271

(−0.7205)

lnURB

−0.1395

(−0.5972)

−0.4421

(−0.7670)

−0.5816

(−0.9338)

lnER

0.1503^***

(4.3380)

0.2775^***

(3.0192)

0.4277^***

(3.9433)

lnRD

−0.0235

(−0.7803)

−0.1919^***

(−3.8067)

−0.2154^***

(−4.0307)