Technical Background Report to the Global Mercury Assessment 2018 [Pre-print]

This document provides the technical background to the Global Mercury Assessment 2018, developed in response to a decision taken at the twenty-seventh session of the Governing Council of the United Nations Environment Programme that requested an update to the 2013 assessment within six years. It describes the methods and data used to compile the 2015 global inventory of anthropogenic mercury emissions to air and releases to other environmental media, including sector definitions, activity data sources, emission factors, technology profiles, and uncertainty procedures. It also explains updates from earlier inventories, approaches for geospatial distribution, and comparisons with national reporting systems. The assessment summary for policy-makers was delivered to the fourth session of the United Nations Environment Assembly in March 2019.