Table 3 HR (95% CI) for all-cause mortality considering both NO₂ and PM_2.5

Model a

Per 10 μg/m3 increment

 NO₂

10,759

0.978 (0.950, 1.008)

0.148

 PM_2.5

10,759

1.252 (1.227, 1.279)

 < 0.001

Model b

NO₂ (μg/m3)

  [ 1.22, 10.00)

2704

1.111 (0.965, 1.278)

0.143

  [ 10.00, 20.00)

4564

0.980 (0.861, 1.114)

0.753

  [ 20.00, 30.00)

2216

1.101 (0.970, 1.250)

0.136

  [ 30.00, 40.00)

786

1.019 (0.884, 1.174)

0.795

  [ 40.00,109.04]

489

Reference

/

PM_2.5 (μg/m3)

  [ 14.8, 25.0)

218

0.171 (0.134, 0.218)

 < 0.001

  [ 25.0, 35.0)

1149

0.209 (0.183, 0.237)

 < 0.001

  [ 35.0, 50.0)

3834

0.516 (0.473, 0.563)

 < 0.001

  [ 50.0, 70.0)

4226

0.728 (0.677, 0.783)

 < 0.001

  [ 70.0,133.1]

1332

Reference

/

Model c

Combination of NO₂ and PM_2.5 (median cut-off)

 NO₂ < 16 & PM2.5 < 51

3701

Reference

/

 NO₂ ≥ 16 & PM2.5 < 51

1765

1.295 (1.197, 1.401)

 < 0.001

 NO₂ < 16 & PM2.5 ≥ 51

1889

1.641 (1.521, 1.770)

 < 0.001

 NO₂ ≥ 16 & PM2.5 ≥ 51

3404

1.843 (1.715, 1.981)

 < 0.001

Model d

Combination of NO₂ and PM_2.5 (guideline cut-off)

 NO₂ < 20 & PM_2.5 < 35

1221

Reference

/

 NO₂ ≥ 20 & PM_2.5 < 35

146

1.797 (1.380, 2.338)

 < 0.001

 NO₂ < 20 & PM_2.5 ≥ 35

6047

2.756 (2.501, 3.038)

 < 0.001

 NO₂ ≥ 20 & PM_2.5 ≥ 35

3345

3.241 (2.909, 3.610)

 < 0.001