Table 1 Distribution of SO2 and NO2 concentrations in 2-year average among 4 districts in Ulaanbaatar, 2015–2016
|  | Mean ± SD | Min | 25 | 50 | 75 | Max |
|---|---|---|---|---|---|---|
District/SO2 (ppb) | ||||||
  A | 5.2 ± 6.7 | 0.0 | 0.8 | 2.6 | 2.6 | 36.0 |
  B | 4.4 ± 6.3 | 0.0 | 1.2 | 2.9 | 5.5 | 39.0 |
  C | 10.1 ± 14.4 | 0.0 | 1.1 | 3.2 | 14.5 | 63.0 |
  D | 7.1 ± 9.2 | 0.0 | 0.6 | 3.8 | 11.0 | 46.0 |
District/NO2 (ppb) | ||||||
  A | 30.0 ± 17.9 | 12.0 | 18.0 | 24.0 | 36.8 | 86.0 |
  B | 27.7 ± 15.4 | 7.0 | 17.0 | 23.0 | 33.8 | 74.0 |
  C | 30.0 ± 20.2 | 4.0 | 17.0 | 23.0 | 36.8 | 99.0 |
  D | 18.2 ± 15.8 | 3.0 | 8.0 | 10.5 | 26.0 | 68.0 |