The concept of BAT was introduced as a key principle in the IPPC Directive 96/61/EC (Directive 2008/1/EC codified version). This Directive has been incorporated into law by the Protection of the Environment Act 2003, with the former BATNEEC (Best Available Technology Not Entailing Excessive Costs) replaced with BAT.
BAT is defined in Section 5 of Environmental Protection Agency Acts, 1992 and 2003, and Section 5(2) of the Waste Management Acts 1996 to 2005, as the "most effective and advanced stage in the development of an activity and its methods of operation, which indicate the practical suitability of particular techniques for providing, in principle, the basis for emission limit values designed to prevent or eliminate or where that is not practicable generally to reduce an emission and its impact on the environment as a whole".
The overall objective of ensuring a high level of protection for the environment will often involve making a judgment between different types of environmental impact, often influenced by local site considerations. However, the obligation to ensure a high level of environmental protection, including the minimisation of long-distance or trans-boundary pollution, implies that the most appropriate techniques cannot be set on the basis of purely local considerations.
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