Air pollution mitigation is scored in the Woodland Opportunity Map (WOM) using two different datasets identifying the ability to mitigate impacts from PM2.5 (on human health) and Ammonia (primarily for impacts on ecosystems as benefits for human health are covered under PM2.5). Due to the two separate types of impact (human health, ecosystems), two separate layers were required to show where woodland creation would best mitigate these impacts. The scores from each of these layers are halved then combined in order to avoid air pollution being double weighted relative to other scoring layers. This layer shows the opportunity for trees to remove air pollution in the form of Ammonia. Ammonia emissions have only slightly declined in the past 20 years, but have been increasing again in the period 2015-2017. Ammonia remains of major environmental concern due to adverse effects on forests, species composition of semi-natural ecosystems and soils. Tree planting can have a beneficial effect as a landscape structure to mitigate Ammonia air pollution through 1. Reducing emissions from slurry lagoons by reducing the wind speed over its surface. 2. Recapturing and diluting emissions from sources upwind of the trees through increased turbulence and deposition velocities. 3. Increasing the dispersion above the canopy through increased mixing thereby reducing deposition to nearby sensitive habitats. Planting trees in areas of high ammonia emissions can intercept ammonia reducing the pressure from ammonia deposition on habitats downwind, can help dilute and disperse ammonia and will also reduce secondary formation of PM2.5. The ammonia data used here is based on National Atmospheric Emissions Inventory (NAEI) ammonia emissions data 2018. Scoring is based on NAEI breakpoints outlined in their website, which shows ammonia emissions in terms of tonnes per square kilometre.

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Creation date:
04 August 2021
Open Government Licence for Public Sector Information (OGL)

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features, GWC21_Air_Quality_Ammonia_Dissolve_Score
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