Ammonia contents in and emission from dust particles collected in livestock buildings

The aim of the study was to explore the nature of the ammonia in dust parti cles from livestock buildings. This is assumed to be important for obtainin g better understanding of the role of dust in the perception of odour and t he development of respiratory diseases in farmers' lungs. Sediment dust samples were collected in swine and poultry buildings. About 3 g of dust was packed between two glass fibre filters in a 37 mm dust samp ler cassette and exposed to clean air at an air flow rate of 1 l m(-1). The ammonia emitted to the air was determined by using the 0.5% boric acid tra p and indo-phenol method. During the first exposure hours the rate of ammon ia emission, mu g NH3 min(-1) g(-1), decreased rapidly to a level, where th e rate of ammonia emission decreased slowly over a long exposure period. It was from about 1 to 0.3 mu g NH3 min(-1) g(-1) during an exposure period f rom 5 to 53 hours. Slow and continuous ammonia emission from both poultry a nd swine dust during a long exposure period indicates that ammonia molecule s are strongly bound inside the dust particles. The porous structures of du st particles suggest that this slow and constant ammonia emission is mainly caused by ammonia molecule diffusion within the dust particles. The ammonia content of dust samples was determined by using distillation in alkaline water solution, the 0.5% boric acid trap and indo-phenol method. The ammonia contents in sediment and airborne dust collected in poultry, sw ine and cow buildings ranged from 1 to 20 mg per 1 g of dust, i.e. 1,000 an d 20,000 ppm, weight basis. Dust particles are able to carry ammonia molecu les. The particles deposited in the olfactory organ and the respiratory sys tem may act like time release pills and cause high ammonia concentrations j ust around the particles.