Article 6
1
In underground mining and tunnelling, Member States may benefit from a transitional period ending at the latest on 21 August 2023, as regards the limit values for nitrogen monoxide, nitrogen dioxide and carbon monoxide.
2
During the transitional period referred to in paragraph 1, Member States may continue to apply the following, instead of applying the limit values established in the Annex:
a
in respect of nitrogen monoxide: the existing limit values established in accordance with the Annex to Directive 91/322/EEC;
b
in respect of nitrogen dioxide and carbon monoxide: national limit values in force on 1 February 2017.