Emissions to air from agriculture include ammonia (NH3), particulate matter (PM), and bioaerosols. A main source of NH3 is livestock manures. Estimates of UK NH3 emissions show that around 82% of agricultural emissions are from livestock manures. Particulate matter emissions occur directly from farming activities, and from reaction of NH3 with acidic pollutants to form fine particles (PM2.5, i.e. particles with diameter of 2.5 μm or less). Air pollution emissions from most industrial and domestic sectors in the UK are declining, but those from agriculture are not and are attracting public health attention.The study reported here formed part of larger project that sought to provide evidence for the link between agricultural air pollution mitigation interventions and human health outcomes. The objective of this study was to provide evidence to support the use of emissions data, largely from other peer-reviewed reports, to model pollutant dispersion. The evidence is in the form of emissions data from livestock buildings (pigs, poultry and dairy). The measurements do not attempt to represent UK agriculture, but provide data that are additional to published data, for validation of emission factors chosen to estimate dispersion and exposure. Measurements were taken at five farms in the UK: two pig, two poultry, and one dairy farm, with measurement periods distributed over one year to align with production practices. The primary objective was to measure the emissions of ammonia from these activities. Los Gatos laser-based cavity ring down and Gasmet Fourier Transform infrared (FTIR) analysers enabled the continuous measurement of gaseous component concentrations. TSI Bluesky analysers were used to measure house internal particulate PM concentrations. Volume flowrates were determined from fan performance data or using surrogate measurements such as carbon dioxide concentration. Data were processed to produce ammonia emission values. The emission values presented in the results of this study are highly variable, as would be expected because of differences in design of the housing, feeding strategies, environmental factors (such as temperature, humidity), and how the manure is managed. Values are presented showing that, for pigs and poultry, emission values are similar to published values. For dairy, the values presented in the results of this study are lower than published values. The values presented are aligned with published values for pigs and poultry, giving confidence that the published values are applicable for modelling dispersion and exposure. For dairy farm emissions, the values measured in this study are lower than the published values, but with high uncertainty, suggesting that peer reviewed emission factors are appropriate for the modelling study rather than the values presented here.The main limitations of this study relate to the difficulty in sampling air to gain representative measurements of concentration; and the determination of the ventilation rates of buildings. This project was funded by the National Institute for Health and Care Research (NIHR) AIM-HEALTH programme.
Leonard et al. (Fri,) studied this question.