1. Sampling points directed at the protection of human health must be sited to provide data on—
(a)the areas within zones where the highest concentrations occur to which the population is likely to be directly or indirectly exposed for a period which is significant in relation to the averaging period of the limit value(s); and
(b)levels in other areas within the zones which are representative of the exposure of the general population.
2. Sampling points must in general be sited to avoid measuring very small micro-environments in their immediate vicinity. Where feasible, sampling points must be located so as to be representative of air quality in a street segment of no less than 100m in length at traffic-orientated sites or an area of at least 250m x 250m at industrial sites.S
3. Sampling points in urban background locations must be located so that their pollution level is influenced by the combined contribution from all sources upwind of the station. The pollution level should not be dominated by a single source unless such a situation is typical for a larger urban area. Those sampling points must, as a general rule, be representative for several square kilometres.S
4. Where the objective is to assess rural background levels, the sampling point must not be influenced by agglomerations or industrial sites in its vicinity, i.e. closer than five kilometres.S
5. Where contributions from industrial sources are to be assessed, at least one sampling point must be installed downwind of the source in the nearest residential area. Where the background concentration is not known, an additional sampling point must be situated within the main wind direction.S
6. Sampling points must also, where possible, be representative of similar locations not in their immediate vicinity.S
7. Account must be taken of the need to locate sampling points on islands, where that is necessary for the protection of human health.S
8. Sampling points targeted at the protection of ecosystems or vegetation must be sited more than 20 km away from agglomerations or more than 5 km away from other built-up areas, industrial installations or motorways or major roads with traffic counts of more than 50,000 vehicles per day.
9. Sampling points must be located so as to be representative of air quality in a surrounding area of at least 1000 km². A sampling point may be sited at a lesser distance or to be representative of air quality in a less extended area, taking account of geographical conditions or opportunities to protect particularly vulnerable areas. Account must be taken of the need to assess air quality on islands.S