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Agriculture is responsible for 98% of atmospheric ammonia (NH3) in Ireland, of which pigs and poultry produce 7%; with laying hens specifically contributing 0.6%. Though a small proportion of the national NH3 total emissions, the ecological impacts on sensitive sites attributed to laying hen farms can be substantial. NH3 emission monitoring was conducted in Spring (February to March) and Summer (July to August) 2016 to account for seasonal variation. The total average emission and ventilation rate was 0.25 g bird−1 day−1 and 931 cm3 s−1 bird−1. This is lower than the previously used emission factor for the Irish national inventory of 0.5 g bird−1 day−1, but broadly similar to factors reported in the United Kingdom (UK) and the European Union (EU). Dispersion modelling using monitored data indicated potentially acute effects within 84 m, critical level exceedance within 312 m and exceedance of 0.3 kg N ha−1 year−1 deposition within 2.9–5.2 km. The sensitivity of the model was tested using SCAIL-Agriculture emission and ventilation rates which showed P-values for one tailed critical level below 0.01 for all models, indicating that when normalised the maximum extents modelled by AERMOD were significantly different. This analysis showed emission rate having more influence than ventilation rate. Both parameters combined had the greatest increase in dispersion extent, on average 55.8% greater than the use of monitored rates. A deposition rate of 0.3 kg N ha−1 year−1 was modelled to occur within 5.1–7.7 km when using SCAIL-Agriculture rates. Indicating that the use of SCAIL-Agriculture recommended emission and ventilation rates would have been sufficiently precautionary to assess negative ecological effects on a Natura 2000 site under the Habitats Directive (92/43/EEC). In relation to Appropriate Assessment (AA) screening, the use of any contribution from a source within a set distance may be an appropriate full AA trigger. ; Environmental Protection Agency

Chartered Institute of Ecology and Environmental Management (CIEEM) 2020 Spring Conference (CIEEM 2020), Sheffield, United Kingdom, 4 March 2020 ; Since 2016 Ireland has exceeded it's National Emissions Ceilings Directive limit for ammonia. With government led agricultural expansions (Food Wise 2025) it will be difficult for Ireland not only to meet targets required by the NECD Directive, but also to comply with the EU Habitats Directive to protect against environmental impacts on sensitive sites. ; Environmental Protection Agency

Endotoxin is a bioaerosol component that is known to cause respiratory effects in exposed populations. To date, most research focused on occupational exposure, whilst much less is known about the impact of emissions from industrial operations on downwind endotoxin concentrations. A review of the literature was undertaken, identifying studies that reported endotoxin concentrations in both ambient environments and around sources with high endotoxin emissions. Ambient endotoxin concentrations in both rural and urban areas are generally below 10 endotoxin units (EU) m−3; however, around significant sources such as compost facilities, farms, and wastewater treatment plants, endotoxin concentrations regularly exceeded 100 EU m−3. However, this is affected by a range of factors including sampling approach, equipment, and duration. Reported downwind measurements of endotoxin demonstrate that endotoxin concentrations can remain above upwind concentrations. The evaluation of reported data is complicated due to a wide range of different parameters including sampling approaches, temperature, and site activity, demonstrating the need for a standardised methodology and improved guidance. Thorough characterisation of ambient endotoxin levels and modelling of endotoxin from pollution sources is needed to help inform future policy and support a robust health-based risk assessment process.