Initial Isolation Zone/Distance and Protective Action Zone

The ERG green pages provide a valuable resource for establishing Initial Isolation Zone and Distance, and Protective Action Distances to protect people from vapors resulting from spills involving dangerous goods that are considered toxic by inhalation. The zones associated with these materials are as follows:

  • Initial Isolation Zone—Area surrounding the incident in which persons may be exposed to dangerous upwind and threatening downwind concentrations of the material that is being released
  • Initial Isolation Distance—Radius of the Initial Isolation Zone surrounding the spill in ALL DIRECTIONS
  • Protective Action Zone—Area downwind from the incident in which persons may become incapacitated and unable to take protective action and incur serious or irreversible health effects when exposed to the material that is released
Initial isolation and protective action zone chart, containing a spill represented by a black dot, a dark gray initial isolation zone surrounding it, and a cone of a lighter gray area extending to the right, with “downwind distance” written in the middle. A black rectangle extends above and below the spill to the far right edge of the downwind distance, labeled as the Protective Action Zone. With the wind direction arrow above that, moving from left to right, upwind to downwind. Along the right edge, the text “crosswind directions” with “1/2 downwind distance” above and below the central line of the protective action zone.