The Conservation Agencies are required to assess the condition of each designated site. To do this the agencies are instituting a CSM (common standards monitoring) scheme to determine the condition of each site at regular (6 yearly) intervals. Sites may be under threat from a wide variety of forces such as inappropriate use and management, climate change, invasive species, pollution and so on. Unfortunately the link between cause and effect can take many years to manifest itself, and in addition it may be difficult to attribute a single cause to an observed effect (as multiple causes can generate very similar looking effects).
The authors have considered a number of options for assessing the risks of airborne pollutants to terrestrial designated sites. Some methods would impose very considerable resource commitments from the agencies. Because air pollution is only one of many potential negative impacts on designated sites and because of realistic resource constraints we recommend that a simple hierarchical or staged approach is adopted. Stage 1 is a centralised automated screening of all sites making use of national data and internationally agreed protocols. In many cases the pollution levels will be either so high or so low as to be able to clearly assess the risk to the sites (in the framework of the CSM). Some sites will be receiving pollutants at a rate where it is unclear if the critical load or level is being exceeded; in those cases we recommend that Stage 2 be performed. In Stage 2 the analysis is repeated using whatever site specific data is available. In many cases the most important single piece of site specific information will be on the soil series relevant the designated feature. Finally we recommend that surveyors visiting the sites as part of the CSM be additionally tasked to record the presence of potential sources of pollutant not likely to be included in national data sets (eg new intensive livestock facilities close to the designated sites) and to record the general condition of the vegetation (to provide qualitative confirmation of the predictions in Stage 1 & Stage 2).