This dataset consists of ammonia (NH3) measurements at three sites on Fenn’s, Whixall, Bettisfield, Wem and Cadney Mosses SSSI on the border of Wrexham County Borough (North Wales) and Shropshire (West Midlands). The ammonia measurements are taken from a set of ALPHA (R) (Adapted Low-cost Passive High Absorption) samplers from July to December in the year 2018. The sites were established in order to monitor ammonia during implementation of Site Nitrogen Action Plan (SNAP), as part of the Marches Mosses BogLIFE project. This project aims to restore Britain's third largest lowland raised bog within the Fenn’s, Whixall & Bettisfield Mosses and Wem Moss National Nature Reserves near Whitchurch, Shropshire and Wrexham in Wales. Full details about this dataset can be found at https://doi.org/10.5285/c6145da7-ec61-49ae-a050-f5c5acd6cf9e