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SCHEDULE 6 continued PART 2
3. The Table below sets out the minimum number of sampling points for fixed measurements to assess compliance with limit values for the protection of ecosystems or vegetation in zones other than agglomerations.
| If maximum concentrations exceed the upper assessment threshold | If maximum concentrations are between the upper and lower assessment thresholds |
|---|---|
| 1 station every 20,000 km2 | 1 station every 40,000 km2 |
4. In island zones, the number of sampling points for fixed measurement should be calculated taking into account the likely distribution patterns of ambient-air pollution and the potential exposure of ecosystems or vegetation.
5. This Part sets out the minimum number of sampling points for fixed measurement of Group B pollutants to assess compliance with target values for the protection of human health in zones where fixed measurement is the sole source of information.
| Population of zone (thousands) | If maximum concentrations exceed the upper assessment thresholda | If maximum concentrations are between the upper and lower assessment thresholds | ||
|---|---|---|---|---|
| Arsenic, Cadmium, Nickel | Benzo(a) pyrene | Arsenic, Cadmium, Nickel | Benzo(a)pyrene | |
a
To include at least one urban-background station and for benzo(a)pyrene also one traffic-oriented station provided this does not increase the number of sampling points. |
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| 0—749 | 1 | 1 | 1 | 1 |
| 750—1,999 | 2 | 2 | 1 | 1 |
| 2,000—3,749 | 2 | 3 | 1 | 1 |
| 3,750—4,749 | 3 | 4 | 2 | 2 |
| 4,750—5,999 | 4 | 5 | 2 | 2 |
| =<6,000 | 5 | 5 | 2 | 2 |
6. For the assessment of pollution in the vicinity of point sources, the number of sampling points for fixed measurement should be determined taking into account emission densities, the likely distribution patterns of ambient air pollution and potential exposure of the population. The sampling points should be sited such that the application of the measures referred to at regulation 7(2)(b) can be monitored.
7. Except insofar as otherwise provided by regulation 15(5) or (6), the minimum number of sampling points for fixed continuous measurement to assess air quality in view of compliance with the target values, long-term objectives and information and alert thresholds where continuous measurement is the sole source of information is set out in the table below.
| Population of zone (thousands) | Agglomerations (urban and suburban)a | Other zones (suburban and rural)a | Rural background |
|---|---|---|---|
a
At least 1 station in suburban areas, where the highest exposure of the population is likely to occur. In agglomerations at least 50% of the stations should be located in suburban areas. |
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b
1 station per 25,000 km2 for complex terrain is recommended. |
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| 0—249 | 1 | 1 station/50,000 km2 as an average density over all zones in Walesb | |
| 250—499 | 1 | 2 | 1 station/50,000 km2 as an average density over all zones in Walesb |
| 500—999 | 2 | 2 | 1 station/50,000 km2 as an average density over all zones in Walesb |
| 1,000—1,499 | 3 | 3 | 1 station/50,000 km2 as an average density over all zones in Walesb |
| 1,500—1,999 | 3 | 4 | 1 station/50,000 km2 as an average density over all zones in Walesb |
| 2,000—2,749 | 4 | 5 | 1 station/50,000 km2 as an average density over all zones in Walesb |
| 2,750—3,749 | 5 | 6 | 1 station/50,000 km2 as an average density over all zones in Walesb |
| 3,750 or more | 1 additional station per 2 million inhabitants | 1 additional station per 2 million inhabitants | 1 station/50,000 km2 as an average density over all zones in Walesb |
The Air Quality Standards (Wales) Regulations 2007