The US Department of Transportation (DOT) and Transport Canada (TC) publish the Emergency Response Guidebook (ERG), which provides valuable information to first responders during the initial phase of a dangerous goods/hazardous materials transportation incident. A new edition of this guidebook is published every four years, the most recent edition being published in 2012. There are some changes to the 2012 edition that Emergency Responders should know and understand. One change is that the distances in Table 1, the green pages, have decreased for chlorine (see Table 1 below).