Changes made by 2004/279/EC: Commission Decision of 19 March 2004 concerning guidance for implementation of Directive 2002/3/EC of the European Parliament and of the Council relating to ozone in ambient air (notified under document number C(2004) 764)
EU Decision 2004/279
No changes made by 2004/279/EC: Commission Decision of 19 March 2004 concerning guidance for implementation of Directive 2002/3/EC of the European Parliament and of the Council relating to ozone in ambient air (notified under document number C(2004) 764) are recorded.
From legislation.gov.uk's record of changes, the official one: see it there.