This is Part 2 of the Resource Compendium of Pollutant Release and Transfer Registers (PRTR) Release Estimation Techniques. It defines diffuse sources and discusses how diffuse source data are collected, describes the different types of techniques available for various diffuse sources and discusses how to identify or calculate the input data for the techniques. One final point raised in this document is that there are release data available in various emission inventories. However, most PRTR programmes have yet to integrate such data. (While a PRTR is not an emission inventory per se, these inventories provide examples on how releases from diffuse sources are included and calculated). In the future, countries may wish to look at the data sources available to determine whether such data can be integrated into annual PRTR reports.

Part 2 of the Resource Compendium specifically addresses estimation techniques for releases from diffuse sources, provides guidance and information on what techniques are available and notes the locations of where this information might be found. While this document is not a comprehensive guide of all techniques available and all source categories, it does provide a wide range of information about techniques currently used in a large number of OECD countries.