Table 2 Association of air pollution intensity and depressive symptoms and the role of chronic disease (N = 23,268)

Log of SO₂ intensity

1.266***

0.107

1.093***

0.116

–

–

–

–

Log of TSP intensity

–

–

–

–

1.318***

0.082

1.115***

0.092

Chronic disease

–

–

1.384***

0.068

–

–

1.388***

0.068

Log of SO₂ intensity × Chronic disease

–

–

0.217***

0.084

–

–

–

–

Log of TSP intensity × Chronic disease

–

–

–

–

–

–

0.281***

0.071

Log of average monthly temperature

0.189**

0.085

0.176**

0.085

0.201**

0.087

0.191**

0.087

Log of average monthly relative humidity

− 0.690**

0.333

− 0.693**

0.332

− 0.445

0.335

− 0.451

0.333

Age group

 50–59

0.248***

0.090

0.134

0.089

0.263***

0.090

0.148*

0.089

 60–69

0.148

0.105

− 0.057

0.104

0.174*

0.104

− 0.031

0.103

 More than 70

− 0.396***

0.131

− 0.606***

0.130

− 0.368***

0.131

− 0.578***

0.130

 Male

1.270***

0.091

1.269***

0.090

1.282***

0.091

1.283***

0.090

 Unmarried

0.680***

0.121

0.701***

0.119

0.682***

0.121

0.701***

0.119

 Living in urban area

− 0.400***

0.104

− 0.398***

0.103

− 0.395***

0.104

− 0.387***

0.103

Education

 No education but can read/write

0.414***

0.118

0.373***

0.116

0.416***

0.118

0.376***

0.116

 Primary school

− 0.043

0.112

− 0.081

0.110

− 0.039

0.112

− 0.077

0.110

 Junior high school and above

− 0.470***

0.114

− 0.454***

0.112

− 0.461***

0.114

− 0.448***

0.112

Employment status

 Self− employed

− 0.165*

0.089

− 0.109

0.088

− 0.152*

0.088

− 0.096

0.088

 Wage earner

− 0.351***

0.090

− 0.262***

0.089

− 0.354***

0.090

− 0.265***

0.089

Insurance

 NCMS and URBMI

− 0.061

0.130

− 0.123

0.129

− 0.052

0.129

− 0.113

0.128

 UEMBI

− 0.432***

0.152

− 0.520***

0.151

− 0.418***

0.151

− 0.503***

0.150

Income group

 21–40th percentile

0.328***

0.100

0.335***

0.099

0.340***

0.100

0.349***

0.099

 41–60th percentile

0.078

0.096

0.068

0.095

0.091

0.096

0.082

0.095

 61–80th percentile

− 0.073

0.096

− 0.068

0.095

− 0.063

0.096

− 0.056

0.095

 81–100th percentile

− 0.289***

0.101

− 0.296***

0.100

− 0.288***

0.101

− 0.295***

0.100

Health behavior

 Current drinker

0.040

0.072

0.108

0.072

0.0459

0.072

0.114

0.072

 Current smoker

− 0.196**

0.081

− 0.156*

0.080

− 0.186**

0.081

− 0.144*

0.080

 Constant

7.165***

1.548

7.025***

1.562

7.219***

1.538

7.079***

1.544

City dummy variables

YES

YES

YES

YES

Adjusted R²

0.139

0.165

0.139

0.165

Wald Chi square

2126***

2596***

2228***

2707***