Table 4 Association of air pollution emission per capita/per unit area and depressive symptoms and the role of chronic disease: Robustness test

Association of air pollution emission per unit area (tons per square kilometer) and depressive symptoms and the role of chronic disease among respondents without mental-related chronic disease: Tobit model (N = 10,508)

 Log of SO₂ emission per unit area

0.191

0.163

0.156

0.153

–

–

–

–

 Log of TSP emission per unit area

–

–

–

–

0.490***

0.132

0.419***

0.161

 Chronic disease

–

–

0.856***

0.107

–

–

0.861***

0.094

 Log of SO₂ emission per unit area × chronic disease

–

–

0.161*

0.093

–

–

–

–

 Log of TSP emission per unit area × chronic disease

–

–

–

–

–

–

0.284**

0.124

 Sigma(u)

2.088***

0.063

2.040***

0.079

2.092***

0.057

2.043***

0.072

 Sigma(e)

3.453***

0.042

3.456***

0.040

3.449***

0.037

3.451***

0.040

 Log likelihood

− 29,375

− 29,329

− 29,368

− 29,320

Association of air pollution emission per capita (tons per 10 thousand people) and depressive symptoms and the role of chronic disease among respondents without mental-related chronic disease: Tobit model (N = 10,508)

 Log of SO₂ emission per capita

0.359***

0.122

0.332**

0.137

–

–

–

–

 Log of TSP emission per capita

–

–

–

–

0.615***

0.121

0.564***

0.122

 Chronic disease

–

–

0.860***

0.114

–

–

0.865***

0.088

 Log of SO₂ emission per capita × chronic disease

–

–

0.145

0.105

–

–

–

–

 Log of TSP emission per capita × chronic disease

–

–

–

–

–

–

0.211*

0.118

 Sigma(u)

2.089***

0.072

2.041***

0.057

2.093***

0.081

2.046***

0.076

 Sigma(e)

3.452***

0.041

3.455***

0.034

3.447***

0.048

3.449***

0.037

 Log likelihood

− 29,374

− 29,329

− 29,365

− 29,319