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Average ratio for March, April, and May 2019 and 2020, based on TROPOMI satellite information.
| 2019 |
2020 |
|||||
|---|---|---|---|---|---|---|
| March | April | May | March | April | May | |
| CO/NO2 | 129 | 189 | 209 | 131 | 228 | 251 |
| CH2O/NO2 | 1.14 | 1.46 | 1.51 | 1.29 | 1.30 | 1.50 |
| CO/CH2O | 114 | 129 | 138 | 108 | 176 | 168 |
