
| 2012 | Change in per cent | ||
|---|---|---|---|
| Since 1990 | 2011 - 2012 | ||
| 1Does not include international sea and air traffic. | |||
| Nitrogen oxides (NOX) | 173 | -11.7 | -4.0 |
| Sulphur dioxide (SO2) | 18 | -65.7 | -4.8 |
| Ammonia (NH3) | 26 | 8.7 | 0.4 |
| Non-methane volatile organic compounds (NMVOC) | 132 | -54.8 | -4.7 |
| Carbon monoxide (CO) | 298 | -60.2 | -4.4 |