[Gas and particle emissions from housing in animal production]

Animal agriculture is increasingly regarded as a source of pollutants such as gases, odours and particulates which may be both aggravating and ecologically harmful. An overview of the origin, number and quantity of pollutants emitted from animal housing and from manure stores is presented and possible means of preventing or reducing them are discussed. Of the 136 trace gases in the air of animal houses ammonia (NH3), methane (CH4) and nitrous oxide (N2O) present the greatest risk to the environment. The gases and particulates are emitted principally from freshly deposited and stored excreta, from animal feed, from litter and from the animals themselves. Total NH3 emissions from animal production in Germany are estimated as approximately 750,000 t/a. It is calculated that the average of which is higher than the average "critical loads" for most natural habitats. However, there is still a shortage of satisfactory information on the extent of emissions, in particular on those from naturally ventilated animal houses. NH3 has a direct effect on the trees in the vicinity of animal houses and is also transported long distances through the air contributing to eutrophication and acidification of water and soil. This frequently results in changes in plant ecology, hence reducing plant diversity. CH4 and N2O contribute to the "greenhouse effect". Emissions of CH4 from animal husbandry in Germany are estimated at about 1.5 Mt/a. This corresponds to 0.2% of the assumed global emission from all sources. There is still little knowledge about the quantities of N2O released from agricultural animals. The concentration of airborne microorganisms in livestock housing is between some 100 and several 1000 per liter of air.(ABSTRACT TRUNCATED AT 250 WORDS)