The Agreement concerning the International Carriage of Dangerous Goods by Road (ADR) is intended to increase the safety of international transport of dangerous goods by road. This revised version is based on changes applicable from 1 January 2021. It contains new or revised provisions concerning in particular the transport of electrical storage systems (including lithium batteries installed in goods transport units and defective batteries) medical waste and radioactive materials. The COVID-19 pandemic has led to an increase in demand for medical gases (particularly medical oxygen) which along with infectious hazardous or radioactive substances are being transported with special care and are covered in this edition.