Government of Canada navigation bar

Symbol of the Government of Canada

Primary site navigation bar


  1. Home
  2. Transport Canada
  4. Emergency Response Guidebook 2016
  5. Table 1 - Initial Isolation and Protective Actions Distances

Table 1 - Initial Isolation and Protective Actions Distances

  1. The responder should already have:
    • Identified the material by its ID Number and Name; (if an ID Number cannot be found, use the Name of Material index in the blue-bordered pages to locate that number.)
    • Found the three-digit guide for that material in order to consult the emergency actions recommended jointly with this table;
    • Noted the wind direction.
  2. Look in Table 1 (the green-bordered pages) for the ID Number and Name of the Material involved in the incident. Some ID Numbers have more than one shipping name listed - look for the specific name of the material. (If the shipping name is not known and Table 1 lists more than one name for the same ID Number, use the entry with the largest protective action distances.)
  3. Determine if the incident involves a Small or Large spill and if Day or Night. A Small Spill consists of a release of less than 208 liters (55 US gallons). This generally corresponds to a spill from a single small package (e.g. a drum), a small cylinder, or a small leak from a large package. A Large Spill consists of a release of more than 208 liters (55 US gallons). This usually involves a spill from a large package, or multiple spills from many small packages. Day is any time after sunrise and before sunset. Night is any time between sunset and sunrise.
  4. Look up the Initial Isolation Distance. This distance defines the radius of a zone (Initial Isolation Zone) surrounding the spill in ALL DIRECTIONS. Within this zone, all public should be evacuated (protective clothing and respiratory protection is required in this zone). Persons should be directed to move out of the zone in a direction perpendicular to wind direction (crosswind), and away from the spill, to a minimum distance as prescribed by the Initial Isolation Distance.

    Image describing Initial Isolation Distance

  5. Look up the initial PROTECTIVE ACTION DISTANCE. For a given material, spill size, and whether day or night, Table 1 gives the downwind distance - in kilometers and miles - from the spill/leak source for which protective actions should be considered. For practical purposes, the Protective Action Zone (i.e., the area in which people are at risk of harmful exposure) is a square, whose length and width are the same as the downwind distance shown in Table 1. Protective actions are those steps taken to preserve the health and safety of emergency responders and the public. People in this area should be evacuated and/or sheltered-in-place.
  6. Initiate Protective Actions to the extent possible, beginning with those closest to the spill site and working away from the site in the downwind direction. When a water-reactive TIH (PIH in the US)-producing material is spilled into a river or stream, the source of the toxic gas may move with the current or stretch from the spill point downstream for a substantial distance.

    The shape of the area in which protective actions should be taken (the Protective Action Zone) is shown in this figure. The spill is located at the center of the small circle. The larger circle represents the INITIAL ISOLATION zone around the spill.

Image describing Protective Action Distance
See "Introduction To Green Tables - Initial Isolation And Protective Action Distances" under Factors That May Change the Protective Action Distances
When a product in Table 1 has the mention "(when spilled in water)", refer to Table 2 - Water-Reactive Materials which Produce Toxic Gases for the list of gases produced when these materials are spilled in water.

Call the emergency response telephone number listed on the shipping paper or the appropriate response agency as soon as possible for additional information on the material, safety precautions and mitigation procedures.

Change to imperial units

Small Spills
(From a small package or small leak from a large package)
Large Spills
(From a large package or from many small packages)
First Isolate in all directionsThen Protect persons Downwind duringFirst Isolate in all directionsThen Protect persons Downwind during
IDName of Materialmkmkmmkmkm
  1955   Compressed gas, poisonous, n.o.s. (Inhalation Hazard Zone D)300.10.21000.71.9
  1955   Compressed gas, toxic, n.o.s.1000.52.510005.610.2
  1955   Compressed gas, toxic, n.o.s. (Inhalation Hazard Zone A)1000.52.510005.610.2
  1955   Compressed gas, toxic, n.o.s. (Inhalation Hazard Zone B)300.20.83001.44.1
  1955   Compressed gas, toxic, n.o.s. (Inhalation Hazard Zone C)300.10.31500.92.4
  1955   Compressed gas, toxic, n.o.s. (Inhalation Hazard Zone D)300.10.21000.71.9
  1955   Organic phosphate compound mixed with compressed gas10013.45004.49.6
  1955   Organic phosphate mixed with compressed gas10013.45004.49.6
  1955   Organic phosphorus compound mixed with compressed gas10013.45004.49.6
  1967   Insecticide gas, poisonous, n.o.s.10013.45004.49.6
  1967   Insecticide gas, toxic, n.o.s.10013.45004.49.6
  1967   Parathion and compressed gas mixture10013.45004.49.6
  1975   Dinitrogen tetroxide and Nitric oxide mixture300.10.51000.52.2
  1975   Nitric oxide and Dinitrogen tetroxide mixture300.10.51000.52.2
  1975   Nitric oxide and Nitrogen dioxide mixture300.10.51000.52.2
  1975   Nitric oxide and Nitrogen tetroxide mixture300.10.51000.52.2
  1975   Nitrogen dioxide and Nitric oxide mixture300.10.51000.52.2
  1975   Nitrogen tetroxide and Nitric oxide mixture300.10.51000.52.2
  1994   Iron pentacarbonyl1000.924004.57.4
  2004   Magnesium diamide (when spilled in water)300.10.5600.62.1
  2011   Magnesium phosphide (when spilled in water)600.20.84001.75.7
  2012   Potassium phosphide (when spilled in water)300.10.63001.23.8
  2013   Strontium phosphide (when spilled in water)300.10.53001.13.7
  2032   Nitric acid, red fuming300.10.11500.20.4
  2186   Hydrogen chloride, refrigerated liquid300.10.3Refer to Table 3
  2188   Arsine15013.810005.610.2
  2188   SA (when used as a weapon)3001.95.710008.911.0+
  2189   Dichlorosilane300.10.42001.22.6
  2190   Oxygen difluoride3001.66.710009.811.0+
  2190   Oxygen difluoride, compressed3001.66.710009.811.0+
  2191   Sulfuryl fluoride300.10.53001.94.4
  2191   Sulphuryl fluoride300.10.53001.94.4
  2192   Germane1500.735002.96.7
  2194   Selenium hexafluoride2001.13.46003.47.8
  2195   Tellurium hexafluoride6003.68.6100011.0+11.0+
  2196   Tungsten hexafluoride300.20.71500.92.8
  2197   Hydrogen iodide, anhydrous300.10.31500.92.4
  2198   Phosphorus pentafluoride300.20.81500.82.9
  2198   Phosphorus pentafluoride, compressed300.20.81500.82.9
  2199   Phosphine600.213001.33.8
  2202   Hydrogen selenide, anhydrous3001.75.9100011.0+11.0+
  2204   Carbonyl sulfide300.10.33001.33.2
  2204   Carbonyl sulphide300.10.33001.33.2
  2232   Chloroacetaldehyde300.20.3600.61.1
  2232   2-Chloroethanal300.20.3600.61.1
  2285   Isocyanatobenzotrifluorides300.10.2300.40.6
  2308   Nitrosylsulfuric acid, liquid (when spilled in water)300.10.430012.8
  2308   Nitrosylsulfuric acid, solid (when spilled in water)300.10.430012.8
  2308   Nitrosylsulphuric acid, liquid (when spilled in water)300.10.430012.8
  2308   Nitrosylsulphuric acid, solid (when spilled in water)300.10.430012.8
  2334   Allylamine300.20.51501.42.5
  2337   Phenyl mercaptan300.10.1300.30.4
  2353   Butyryl chloride (when spilled in water)300.10.1300.30.9
  2382   Dimethylhydrazine, symmetrical300.20.3600.71.3
  2395   Isobutyryl chloride (when spilled in water)300.10.1300.20.6
  2407   Isopropyl chloroformate300.10.2600.50.9
  2417   Carbonyl fluoride1000.62.26003.68.1
  2417   Carbonyl fluoride, compressed1000.62.26003.68.1
  2418   Sulfur tetrafluoride1000.52.44002.16
  2418   Sulphur tetrafluoride1000.52.44002.16
  2420   Hexafluoroacetone1000.62.6100011.0+11.0+
  2421   Nitrogen trioxide600.31.11500.93
  2434   Dibenzyldichlorosilane (when spilled in water)300.10.1300.20.6
  2435   Ethylphenyldichlorosilane (when spilled in water)300.10.1300.31
  2437   Methylphenyldichlorosilane (when spilled in water)300.10.2300.41.3
  2438   Trimethylacetyl chloride600.5115023.2
  2442   Trichloroacetyl chloride300.20.3600.61
  2474   Thiophosgene600.61.72002.24.1
  2477   Methyl isothiocyanate300.10.1300.20.3
  2478   Isocyanate solution, flammable, poisonous, n.o.s.600.81.84004.37

” + ” means distance can be larger in certain atmospheric conditions

Date Modified: