The ERG contains an indexed list of dangerous goods and the associated ID number, the general hazards they pose and recommended safety precautions. For example, if emergency responders arrive at the scene of an overturned tractor trailer displaying a DOT hazmat placard, they would use the guide to identify the material associated with the placard and get guidance on how to respond accordingly.

The 2012 version of the ERG includes general revisions, reorganized general information pages and new tables such as Initial Isolation and Protective Action Distances for large spills involving six common toxic inhalation hazard gases. Updated every four years, the ERG is available free to public safety agencies in all states and territories through designated state coordinators’ offices. PHMSA has partnered with the National Library of Medicine to provide this free application as well as a version of the ERG in its Wireless Information System for Emergency Responders (WISER) application.