Ammonia concentrations in dust samples from a fattening unit with bad air quality

Effects of 5 to 150 ppm gaseous ammonia onto respiratory health and production data in pigs have been described in literature with varying results. Ammonia is known to cause oxidative stress in epithelial cells, to irritate nociceptors and to disturb the mucocillary clearance. In addition, a pH-shift within the epithelial lining fluid covering the airways with the consequence of an efficacy loss of pH-dependent natural antibacterial peptides is assumed. In a fattening unit with low gaseous ammonia concentrations but bad air quality leading to airway irritation, dust samples were analysed for bound ammonia. The hypothesis was, that ammonia bound to inhalable dust particles might irritate the mucosa.

Sedimentation dust was sampled on six boards covered with foil in two fattening units with partly slatted floor with 109 and 110 pigs each within two time periods of four and six weeks. Gaseous ammonia was determined by a single gas detector with an accuracy of 1 ppm.

Dust-bound ammonia was quantified photometrically after acidification by the reaction from alpha-ketoglutarate with ammonia to L-glutamate, a method for the quantification of ammonia in plasma with a detection limit of 14.7µmol/l. The variation coefficient in two four-fold determinations in dust samples was 5.4-5.9%.

No respiratory disorders occurred during the examination period and only minor lung lesions were detectable at slaughter checks. Subjective perception of air quality by workers was negative because of airway irritations. Gaseous ammonia was in the range of 0-28 ppm during the examination period. The amount of sedimentation dust was 2.6+0.7 [g/m²/day], which is high in comparison to data from literature. Mean ammonia concentrations were 5.1+1.3 µg/mg dust. With a supposed air dust concentration of 10 mg/m³ this would result in approximately 0.07ppm ammonia in the air.

A relatively high dust load was measured in a fattening unit with partly slatted floor. Not only dust but also dust-bound ammonia might have harmful effects in the respiratory tract. During constant exposure and solubilisation of dust bound ammonia in an approximated volume of 2 ml epithelial lining fluid in the lung, ammonia concentrations with harmful effects shown in cell culture might also occur in the lung. A negative effect of ammonia on phagozytosis of dendritic cells in cell culture has been shown for concentrations of 1.3µg/ml.

Disclosure of Interest: None Declared.