| Mean | SD | Median | Q1 | Q3 | Interquartile range |
---|---|---|---|---|---|---|
One year before test | ||||||
 PM2.5, μg/m3 | 24.35 | 5.17 | 23.93 | 21.05 | 29.18 | 8.13 |
 NO2, ppb | 21.81 | 6.63 | 21.30 | 19.26 | 24.63 | 5.37 |
One month before test | ||||||
 PM2.5, μg/m3 | 21.80 | 7.43 | 20.56 | 16.36 | 26.55 | 10.19 |
 NO2, ppb | 20.75 | 7.21 | 20.09 | 16.00 | 24.23 | 8.24 |