Ammonia (NH₃) emissions from agriculture contribute significantly to air pollution and nitrogen deposition, with implications for human health and sensitive ecosystems. However, long-term field observations comparing NH₃ concentration patterns among different livestock production systems in northern Europe remain limited. This study aimed to quantify temporal and spatial variations in NH₃ concentrations around pig, poultry, and dairy farms and identify the influence of temperature, management practices, and distance from emission sources.</p> <p>Monthly average concentrations were recorded from June 2023 to May 2024 across nine spatially distributed sampling locations around each farm. Annual mean NH₃ concentrations ranged from 1.8–17.0, 5.2–22.5, and 4.0–23.7 µg m⁻³ at the poultry, pig, and dairy farms, respectively. These levels were consistently above nearby background concentrations of 0.44–0.45 µg m⁻³ and exceeded the 1 µg m⁻³ critical level for lichens and mosses at all sites.</p> <p>Concentrations decreased with distance from livestock housing and were positively correlated with ambient temperature at all three farms. The pig and dairy farms showed greater temporal variability than the poultry farm, mainly reflecting manure handling, housing conditions, and other management activities. An April peak at the pig farm was likely related to slurry spreading. These findings show that both continuous housing emissions and episodic manure application elevate NH₃ concentrations near farms. The findings provide a robust observational basis for refining agricultural NH₃ emission inventories and supporting mitigation efforts under national and European air quality and environmental policies.