An emission inventory of livestock-related bioaerosols for Lower Saxony, Germany

Detailed livestock-related emission inventories are now available for gases but not for bioaerosols, which are emitted in significant amounts and in varying compositions. In view of the environmental importance of bioaerosols, a model for their calculation is proposed here. The basic formula multiplies emission factors by the number of farm animals, but the model is extended by a factor which considers provisionally the influence of production cycles of various types of livestock on the estimated emissions. Despite several uncertainty factors, emissions factors are calculated for dust (inhalable, respirable), endotoxins (inhalable, respirable) and microorganisms (total mesophilic bacteria, Enterobacteriaceae, fungi) from ventilated livestock buildings. The calculation model and the emission factors are the basis for a simple geographical information system designed to display the calculated emission potencies of livestock-related bioaerosols for the year 1999 in the 46 districts and autonomous cities in Lower Saxony, Germany. The three highest emissions of inhalable dust were determined for the three animal-dense districts of Grafschaft Bentheim (485.3 kg a(-1) km(-2)), Cloppenburg (648.8 kg a(-1) km(-2)) and Vechta (1203.4 kg a(-1) km(-2)). On the other hand, the lowest bioaerosol emissions were found for the cities of Salzgitter (9.6 kg a(-1) km(-2)), Braunschweig (10.6 kg a(-1) km(-2)) and Wolfenbfittel (12.2 kg a(-1) km(-2)) due to their more urban, non-agricultural setting. With the aid of the agricultural census data, the percentages of temporal emission variations were assessed between 1996 and 1999, and found to have changed distinctly due to fluctuations in animal numbers in the districts. The following changes were noted in the three districts with the greatest increase or decrease of emitted particulate matter from 1996 to 1999: more inhalable dust was emitted in the rural districts of Stade (+ 9.6%), Cloppenburg (+ 14.9%) and Emsland (+ 18.2%), while there were clear declines in Oldenburg City (- 24.1%), the district Helmstedt (- 15.1%) and Braunschweig City (- 14.4%). (C) 2004 Elsevier Ltd. All rights reserved.