Member States shall ensure that, throughout their zones and agglomerations, levels of sulphur dioxide, PM10, lead, and carbon monoxide in ambient air do not exceed the limit values laid down in Annex XI.
In respect of nitrogen dioxide and benzene, the limit values specified in Annex XI may not be exceeded from the dates specified therein.
Compliance with these requirements shall be assessed in accordance with Annex III.
The margins of tolerance laid down in Annex XI shall apply in accordance with Article 22(3) and Article 23(1).