The ammonia emissions from different housing systems and animal species are presented and show that the higher emissions (g ammonia/ hour – livestock unit (500 kg bodyweight)) come from chicken production followed by fattening pigs on fully slatted floor( 2,38 g NH3/ h-LU). Fattening pigs on deep litter come third (2,15 g NH3/ h-LU) followed by fattening pigs on partly slatted floor (less than 50% of the floor surface slatted) (1,35 g NH3/ h-LU) . Lower emissions are measured in nurseries (1,3 g NH3/ h-LU) and farrowing buildings (0,65 g NH3/ h-LU for farrowing and 0,93 for served gilts for sows) as well as for cattle buildings. With the all in -all out technique, as the animal grow, the ventilation rate will also increase which is a factor for increasing ammonia emissions per building. The planning of air cleaning systems become than more complicated.