I.Minimum number of sampling points for fixed measurement to assess compliance with limit values for the protection of human health and alert thresholds in zones and agglomerations where fixed measurement is the sole source of informationU.K.
(a)Diffuse sourcesU.K.
| Population of agglomeration or zone (thousands) | If concentrations exceed the upper assessment threshold | If maximum concentrations are between the upper and lower assessment thresholds | For SO2 and NO2, in agglomerations where maximum concentrations are below the lower assessment threshold |
|---|---|---|---|
| 0-250 | 1 | 1 | not applicable |
| 250-499 | 2 | 1 | 1 |
| 500-749 | 2 | 1 | 1 |
| 750-999 | 3 | 1 | 1 |
| 1 000-1 499 | 4 | 2 | 1 |
| 1 500-1 999 | 5 | 2 | 1 |
| 2 000-2 749 | 6 | 3 | 2 |
| 2 750-3 749 | 7 | 3 | 2 |
| 3 750-4 749 | 8 | 4 | 2 |
| 4 750-5 999 | 9 | 4 | 2 |
| > 6 000 | 10 | 5 | 3 |
| For NO2 and particulate matter: to include at least one urban-background station and one traffic-orientated station |
(b)Point sourcesU.K.
For the assessment of pollution in the vicinity of point sources, the number of sampling points for fixed measurement should be calculated taking into account emission densities, the likely distribution patterns of ambient-air pollution and the potential exposure of the population.