The development of robust methods for measuring concentrations and emission rates of gaseous and particulate air pollutants in livestock buildings

Air pollutants in livestock buildings may represent a risk to the health of both the housed livestock and of the stockmen. Moreover, when these air pollutants leave a building in its ventilation air, they may also represent a risk of pollution to the wider environment. A set of versatile and robust methods for quantifying pollutant emissions was therefore developed for common use during an extensive field survey of livestock buildings (329 sets of measurements) across four Northern European countries. Measurements were made, at seven different positions in each livestock building, of air temperature and relative humidity, and of the concentrations of carbon dioxide, ammonia, airborne dust (both inhalable and respirable), microorganisms and endotoxins. Concentrations of carbon dioxide were continuously measured by an infra-red analyzer while concentrations of ammonia were continuously measured by a chemiluminescence NOx analyzer preceded by a thermal converter. Mass concentrations of inhalable and respirable dust were measured by total filters and cyclone samplers, respectively, and the exposed filters were also assayed for endotoxins. Concentrations of airborne total bacteria, Gram-negative bacteria and total fungi were measured in some of the buildings using a novel automated slit sampler. The ventilation rate of each building was estimated by a balance method from the information on both its internal and external carbon dioxide concentrations, and hence the emission rates of the different aerial pollutants from each building were estimated. The results of applying the methods are reported and discussed in detail in later papers in the series, but as an example of the results obtained, a slurry-based sow unit, monitored over 24 h in wintertime, gave internal carbon dioxide and ammonia concentrations in the ranges 1180-3765 and 5.3-17.4 p.p.m., respectively, along with internal temperatures and relative humidities in the ranges 15.7-20.4 degrees C and 34-69% respectively. Examples of the estimated emission rates from the sow unit, averaged over the 24 h period and corrected for background, were: ammonia 0.86 g NH3/h (hpu) (hpu = heat production unit), inhalable dust 0.19 g/h (hpu), respirable dust 0.02 g/h (hpu), and total bacteria 2.3 M(cfu)/(hpu) where cfu is colony-forming units. (C) 1998 Silsoe Research Institute.