I tilfælde af zoner eller bymæssige områder som omhandlet i stk. 1 skal medlemsstaterne kun opstille luftkvalitetsplaner i henhold til artikel 23, hvis overskridelserne kan tilskrives andre PM10-kilder end sand- eller saltspredning på vejene om vinteren, jf. dog artikel 20.
Without prejudice to Article 20, in the case of zones and agglomerations referred to in paragraph 1 of this Article, Member States need to establish the air quality plan provided for in Article 23 only in so far as exceedances are attributable to PM10 sources other than winter-sanding or -salting of roads.