Paragraph
England and Wales
Alert thresholds for sulphur dioxide and nitrogen dioxide
| Pollutant | Alert threshold M1 |
|---|---|
| Sulphur dioxide | 500 μg/m3 |
| Nitrogen dioxide | 400 μg/m3 |
Information and alert thresholds for ozone
| Purpose | Averaging period | Threshold |
|---|---|---|
| Information | 1 hour | 180 μg/m3 |
| Alert | 1 hour | 240 μg/m3 |
Annotations
Marginal citations
- M1
To be measured over three consecutive hours at locations representative of air quality over at least 100 km2 or an entire zone, whichever is smaller.