Environment and Rural Affairs Monitoring & Modelling Programme ERAMMP Report-77: An Air Quality Target for Welsh Ecosystems

Rowe, E.C.; Perring, M.P.. 2023 Environment and Rural Affairs Monitoring & Modelling Programme ERAMMP Report-77: An Air Quality Target for Welsh Ecosystems. Bangor, UK Centre for Ecology & Hydrology, 27pp. (UKCEH Project no. C06297, C210/2016/2017)

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Air pollution has impoverished ecosystems in Wales and caused widespread losses of biodiversity. The Welsh Government is assessing the need for a new air quality target (or targets) in relation to ecosystems and biodiversity. A specific target for air quality that can readily be related to effects on ecosystems and biodiversity would help to raise awareness of air pollution impacts. This report briefly reviews air pollution effects on ecosystems and biodiversity, and presents the recommendations of a subgroup of the Clean Air Advisory Panel (CAAP) that was convened in 2022-23 to discuss the issue. The subgroup recommended that a target be set on the basis of a specific single metric, with clearly defined baseline and achievement dates. Air pollutants damage ecosystems through direct toxic effects, and by causing eutrophication (over-fertilisation) and acidification. Ammonia is a particularly damaging air pollutant, with severe effects on many mosses and lichens, and forms a large part of the total nitrogen load that falls on Welsh ecosystems. Other atmospheric pollutants such as ozone or heavy metals may harm ecosystems and biodiversity, but evidence of damage from these is less strong than is evidence for damage from ammonia. Ammonia also contributes to the formation of particulate pollution, which is damaging to wildlife as well as to human health. Ammonia pollution is influenced strongly by emissions from within Wales. The subgroup further recommended that the target be based on: a. Ammonia concentration in air. b. Exceedance of the 1 μg NH3 m-3 annual mean critical level, which is currently exceeded over around 50% of Wales. This level is set to protect sensitive mosses and lichens, which are a valuable component of biodiversity, and contribute to water regulation, peat formation and other ecosystem functions. c. The whole extent of Wales, not only on protected sites or mapped habitat areas. Progress towards the target would need to be assessed primarily using modelled data, which can be provided for the whole area of Wales, and are less influenced by year-to-year variation in meteorology. Calibration of model outputs against ammonia measurements is however important, and the current UK measurement network may not provide sufficient coverage to ensure data accuracy. The specific target metric recommended by the CAAP subgroup is the area of Wales where annual mean concentration of ammonia exceeds the 1 μg m-3 annual mean critical level. A target defined in terms of relative change (for example, a 10% decrease in the area where the critical level is exceeded) would be more robust against changes in the measurement and/or modelling methods than an absolute-change target (for example, 40% of Wales below the critical level). The target value would need to be set after scenario modelling has been carried out to assess what is realistically achievable.

Item Type: Publication - Report (Project Report)
UKCEH and CEH Sections/Science Areas: Soils and Land Use (Science Area 2017-)
Funders/Sponsors: Welsh Government
Additional Keywords: ERAMMP
Related URLs:
Date made live: 17 Nov 2023 14:37 +0 (UTC)

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