The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) established by the General Assembly in 1955 assesses the levels and effects of exposure to ionizing radiation on human health and the environment. This is the second of two volumes of scientific annexes that presents the review of the latest scientific evidence and literature from 2007 to 2020 regarding exposure of the public to ionizing radiation from natural and human-made sources and updates the UNSCEAR 2008 Report. It includes collection and analysis of data from published peer-reviewed literature, institutional and governmental reports, data provided by international organizations, as well as review and update as appropriate, of the dose assessment methodologies used in previous UNSCEAR reports.