The De Minimis project was commissioned by JNCC to develop an evidence-based approach for determining when a proposal and its emissions are considered 'nugatory' (taking into account in-combination effects) and can safely be ‘screened out’ of further assessment. The project has been awarded to DTA Ecology in partnership with Air Quality Consultants Ltd (AQC), Ecological Planning & Research (EPR) and the UK Centre for Ecology & Hydrology (UKCEH). It follows AQC’s recent involvement in the Nitrogen Futures project for JNCC.
AQC has been involved in numerous assessments of impacts on Special Areas of Conservation (SACs) and Special Protection Areas (SPAs) under the Habitats Regulations, including more specifically Ashdown Forest, Epping Forest and the Thames Basin Heaths. The key emissions affecting these three areas have been nitrogen and ammonia from road traffic associated with development proposals (both projects and plans). Currently there is no clear basis for defining an increase in concentration or deposition that might be ignored as being of no consequence for the habitat and therefore not requiring further assessment. The same applies to proposals for agricultural premises, as well as industrial sources, especially when the SAC or SPA is some distance from the source – at what point can the increases in concentration and/or deposition be ignored as being nugatory? This is all very challenging for developers and their consultants, as well as for the regulators.
The De Minimis project aims to:
review current screening thresholds or methods in the UK and other countries;
produce a clear, broadly applicable rationale for when an emission is unlikely to act together with other emissions in a meaningful way that would require further assessment in relation to effects of air pollution on ecosystems;
quantify or provide an indicative range of emission types, sizes and situations where this rationale can be robustly applied;
quantify the uncertainty within the chosen method and when the rationale is not applicable; and
provide a non-technical method to apply the recommended approach.
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