Sulfur dioxide emission intensity

lnSI

Industrial soot emission intensity

lnMI

High economic level

Low to medium economic level

High economic level

Low to medium economic level

Independent variable

Policy_t

−1.4694**

(−2.07)

0.2463

(0.34)

0.6276

(0.57)

1.4192

(0.75)

YRD_i×Policy_t

−0.0276

(−0.23)

0.0403

(0.29)

−0.1717

(−0.59)

−0.2121

(−0.62)

PRD_i×Policy_t

−0.0932

(−0.49)

0.0224

(0.17)

−0.0641

(−0.16)

−0.1561

(−0.41)

Control variable

lnPGDP_it

−0.1616

(−0.77)

−0.9988**

(−2.42)

−0.7977***

(−4.23)

−1.4763*

(−1.93)

lnSTR_it

1.5317***

(2.76)

1.7937***

(2.84)

2.6028***

(4.04)

1.6790

(1.57)

lnPOP_it

−0.5406

(−1.11)

0.3971

(0.46)

−0.9923

(−1.16)

−0.3093

(−0.12)

lnUR_it

−0.1536

(−1.21)

−0.2208**

(−2.43)

−0.2878

(−1.47)

−0.0982

(−0.34)

lnSC_it

−0.0050

(−0.06)

−0.0269

(−0.56)

−0.1620

(−1.25)

−0.1215

(−0.86)

lnFE_it

0.0515

(0.14)

−0.0392

(−0.15)

0.0825

(0.16)

0.2990

(0.50)

lnRD_it

−0.0163

(−0.21)

−0.0535

(−0.64)

0.0195

(0.17)

−0.1103

(−0.75)

lnFI_it

−0.0638

(−0.68)

−0.0178

(−0.31)

−0.1443

(−1.08)

−0.0135

(−0.17)

Constant term

2.4940

(0.55)

3.5869

(0.61)

5.5397

(0.81)

10.0621

(0.57)

Time Effect

√

√

√

√

Individual Effect

√

√

√

√

Observations

377

312

377

312

Within R²

0.8706

0.6810

0.4740

0.2702