Part 1 Alert thresholds for nitrogen dioxide and sulphur dioxide
| Nitrogen dioxide | 400 μg/m3 measured over three consecutive hours at locations representative of air quality over at least 100 km2 or an entire zone or agglomeration, whichever is the smaller |
| Sulphur dioxide | 500 μg/m3 measured over three consecutive hours at locations representative of air quality over at least 100 km2 or an entire zone or agglomeration, whichever is the smaller |