Atmospheric ammonia (NH3) gas concentrations were monitored at Ballynahone Bog, a designated site of international and national importance (Special Areas of Conservation, SAC and Areas of Special Scientific Interest (ASSI)) in Northern Ireland, to assess threats from atmospheric nitrogen inputs. Eight NH3 monitoring points were established on the bog at strategic locations in early September 2014 in response to the establishment of a new poultry farm at the southwest edge of Ballynahone Bog in the summer of 2014. The aim of this monitoring was to determine whether NH3 emissions from the poultry farm would increase atmospheric NH3 concentrations and deposition at the adjacent Ballynahone Bog nature reserve and to provide a detailed spatial and source attribution assessment. Monitoring was carried out at monthly intervals, with continuous time-integrated measurements made with passive UKCEH ALPHA® samplers. This report provides a summary and analysis of data for the measurement period between September 2014 and March 2022, analysing spatial and temporal trends and ammonia concentrations over a long timeseries