19.—(1) The Department shall monitor concentrations of—
(a)basic polycyclic aromatic hydrocarbons; and
(b)any additional polycyclic aromatic hydrocarbons which it decides should be monitored,
at monitoring sites designated by it for this purpose.
(2) The Department shall locate each monitoring site—
(a)together with a sampling point for benzo(a)pyrene, where this is possible; or
(b)in any other case, in accordance with those Parts of Schedule 6 relevant to Group B pollutants.
(3) The total number of monitoring sites and their overall selection shall be such as the Department considers necessary to ensure that the monitoring provides sufficient information to identify long-term trends and geographical variation in the concentration of each polycyclic aromatic hydrocarbon.
(4) Regulation 16(2) and (3) shall apply to the monitoring required by this regulation as if such monitoring were an assessment under Chapter 4 of Part 2.