The PRTR defines diffuse sources as "the many smaller or scattered sources from which pollutants may be released to land, air or water." For releases of pollutants into air diffuse sources cover the sectors transportation (road transport, navigation and air traffic), agriculture and households. For pollutant releases into water the sectors include atmospheric deposition, agriculture and urban areas. For each sector the most important pollutants are taken into account. For example, methane (CH4), nitrous oxide (N2O) and ammonia (NH3) are of utmost importance in the agricultural sector. Pollutants from the transportation sector include carbon monoxide (CO), carbon dioxide (CO2), particulate matter (PM10) and nitrogen oxides (NOx/NO2).
Since autumn 2017 data about diffuse sources are available for the public in Thru.de in a comprehensible manner. The models, data and the visualization of results have been developed within two research projects of the German Environment Agency by the partners Karlsruhe Institute of Technology (KIT), Department of Design of the Potsdam University of Applied Sciences, Institute for Energy and Environmental Research (ifeu) and Institute of Energy Economics and Rational Energy Use (IER) of the University of Stuttgart. Visual realization of the edited data for diffuse sources in Thru.de has been done by ENDA GmbH & Co. KG in Berlin.
The PRTR Register of the European Union also provides maps for emissions of some diffuse sources into air and water.
The homepage of the German Environmental Agency contains additional information about the following topics: