Alert thresholds and limit values in Article 13
Limit values (1/2)
For sulphur dioxide, PM10, lead, carbon monoxide, nitrogen dioxide and benzene, Article 13 fixes limit values which must not be exceeded in different zones or agglomerations of a Member State and Article 23 deals with the question, what happens, when a limit value is exceeded. Annex XI provides that limit values for nitrogen dioxide and benzene shall have to be met by 1 January 2010, while for other pollutants, no date for compliance was fixed. However, this was due to the fact that already Directive 1999/30/EC had made compliance with the other limit values compulsory since 2005, so that it was not necessary to fix a new compliance date.
Annex XI fixes one or two limit values for different pollutants. When two limit values are set, they must both be respected in different zones and agglomerations. The limit value may also not be exceeded at any time during the year. This possibility not to respect the limit values during certain moments of a calendar year is a concession which, for example, WHO does not accept for its recommended limit values. It is meant to soften the strictness of the applicable limit value.
Article 13 and Annex XI provide for a margin of tolerance for sulphur dioxide, carbon monoxide, lead and PM10. The margin of tolerance means that public authorities of a Member State, where the limit value is exceeded, only have to intervene and adopt measures, when the limit value plus the margin of tolerance is exceeded. As different margins of tolerance which are laid down in Annex XI, are relatively high - 100 per cent in case of lead, 60 per cent for carbon monoxide and 43 per cent for sulphur dioxide - the limit values are, in practice, less strict than they appear on paper. No margin of tolerance is foreseen in Article 16(2) for PM2.5