§ Mr. BarnesTo ask the Secretary of State for the Environment what are the maximum tolerable concentrations of dioxins and furans which are allowable for differing types of incinerators, power station operations, leachates, sludges and for the aquatic environment; and if he will make a statement.
§ Mr. Maclean[holding answer 20 April 1993]:Authorisations issued by Her Majesty's inspectorate of 326W pollution under integrated pollution control legislation require the operator to use the best available techniques not entailing excessive cost to prevent, or minimise and render harmless the release of prescribed substances, including dioxins, to any environmental medium.
Power stations, compared with other combustion and incineration processes, produce only very small quantities of dioxins and furans so that concentration limits are neither appropriate or specified.
Guidance notes published by the chief inspector of Her Majesty's inspectorate of pollution relating to combustion and incineration processes subject to IPC control suggest an initial limit of 1 ng/M3 TEQ dioxins in releases to air while requiring operators to aim ultimately to achieve one tenth of that limit by the use of progressive techniques. The relevant CI guidance notes are numbered IPR 5/1 to 5 inclusive, IPR 5/7 and IPR 5/11, all of which are in the Library of the House.
As part of the statutory IPC authorisation process the NRA can, in addition to any limits Her Majesty's inspectorate of pollution itself imposes on an operator, require Her Majesty's inspectorate of pollution to impose further limits where the release is directly to controlled waters. Discharges of dioxins and furans to water are typically extremely low and since they are normally bound to particulates, strict control of particulates in the discharge will minimise the release of these pollutants to the environment.
The best solution must be to avoid the generation of dioxins in the first place by employing appropriate operating conditions within the combustion or incineration process and this is what IPC aims to achieve.