Table 2 Correlation table for ambient air pollutant levels within one year before index date

PM2.5 (per 10 μg/m³)

6

1

0.908

0.487

0.052

 − 0.024

0.188

PM10 (per 10 μg/m³)

7

 < 0.01

1

0.518

 − 0.054

 − 0.091

0.301

SO₂ (per 10 ppb)

2

 < 0.01

 < 0.01

1

0.253

0.076

0.007

NO₂ (per 10 ppb)

11

 < 0.01

 < 0.01

 < 0.01

1

0.904

 − 0.760

CO (per 1 ppm)

7

0.20

 < 0.01

 < 0.01

 < 0.01

1

 − 0.670

O₃ (per 10 ppb)

3

 < 0.01

 < 0.01

0.71

 < 0.01

 < 0.01

1