Field Comparison of Methods for Evaluation of Vapor/Particle Phase Distribution of Ammonia in Livestock Buildings

Abstract

Ammonia is a significant respiratory hazard for workers in enclosed livestockbuildings. It is hypothesized that ammonia originating from animal wastes is present inboth vapor phase and adsorbed onto dust (particulate phase), and that this physicaldistribution is an important determinant of deposition in the human respiratorysystem. The goals of this project were: (1) to evaluate the vapor/particle phasedistribution of ammonia in enclosed livestock buildings using annular denuders andimpingers with prefilters; and (2) to compare the annular denuders air samplingmethod to traditional active and passive ammonia sampling methods. Ammonia wassampled and analyzed using six methods: annular denuder systems with ionchromatographic (IC) analysis; impingers with pre-filter and IC analysis; impingerswithout pre-filters with IC analysis; long-term colorimetric tubes; direct readingcolorimetric detector tubes; and passive dosimeters. Field studies were conducted in sixenclosed swine and poultry buildings during the summer season. Analysis of varianceconfirmed by individual t-tests indicated that passive dosimeters and long-termcolorimetric tubes consistently yielded higher ammonia values than the denuder andimpinger methods. Denuder systems were less precise (pooled CV = 0.41) thanimpingers without pre-filters (pooled CV = 0.16), but more precise than impingerswith pre-filters (pooled CV = 0.47). The results of this study indicate that a measurableproportion of ammonia in enclosed livestock buildings is indeed associated withparticles, and that annular denuder systems have potential to be used in thisenvironment for evaluation of phase distributions of ammonia. However, the precisionand overall collection efficiency of the specific annular denuder evaluated was poorcompared to the traditional impinger method, and further work is needed to develop amore suitable denuder system for the relatively higher concentrations of gases andparticulates encountered in agricultural environments.