Relevant periods
3. The relevant period for the purposes of Part IV of the 1995 Act shall be, in relation to an air quality objective, the period beginning with the date on which these Regulations come into force and ending, in respect of the substance specified in column 1 of the Table in the Schedule to these Regulations and the objective relating to that substance specified in column 2 of that Table, on the date set out in the corresponding entry relative to that substance and that objective in column 3 of that Table.