Several factors (some addressed below) determine whether an order to evacuate or protect in place should be given at a hazardous-materials incident. The factors include container size and configuration, whether multiple containers are involved (to assess the ease or difficulty in accessing a breach for possible control), the incident location (including topography and adjacent life hazards), the container`s position (normal, turned, inverted), and weather conditions. The answers to these and other questions will assist the incident commander in making a decision of whether to evacuate or protect in place and plotting a course of action.

The IC should first establish site management with an isolation perimeter and then order the evacuation or attempt to protect the people in place (i.e., shelter in place). If a container catastrophically disintegrates, creating a puff-type cloud that dissipates rapidly, it is better to protect the people in place for this relatively short time. Evac-uation possibly could expose them to the hazardous materials. The building`s protective features should be considered before making a decision.

If protecting in place, order inhabitants to close doors and windows; allow people to go in but not out; control ignition sources; and shut down any heating, ventilation, or air-conditioning systems. Possible shelter-in-place exposures include hospitals, medium- and high-rise apartments, nursing or retirement homes, and schools.


What is the material? Is the material explosive, poisonous, or reactive and highly dangerous?

What is the type of container? Is is pressurized or nonpressurized? How is the container constructed?

What is the container`s location? Is the container in a densely populated area with a subsequent high life hazard or in a remote, unpopulated section? Will the topography (lay of the land) help to confine the product or allow it to run freely toward an exposure? Is the location elevated or depressed? How does the vapor density affect the location? If the container is in a normal position, a hole in the side would allow a portion of the contents to escape, while a bottom breach would empty it. A tank turned on its side could lose half of the container`s contents. A leaking inverted container could be hard to control. For example, it is difficult to plug an open dome cover on a tank truck. In a multiple container incident, the configuration of the tanks is important in accessing and controlling the situation. When the leaking container is inside a “pile-up,” control efforts can be difficult and resources stretched. A leaking container on the outside is usually easy to get to, and control is more feasible in a reasonable time frame if plugging and patching materials are available. The following questions must be considered:

What is the container`s size? Is the container larger or smaller than 10,000 gallons? If smaller, depending on the hazards, it is often safer to protect in place; if larger, it is generally wise to evacuate.

How is the container damaged? What are the type and size of the breach in the container? Can it be controlled in a reasonable amount of time? Are plugging and patching resources and the trained personnel available to do the job?

What is the population density? Is this a sparsely populated rural area or a section of densely populated apartments, tenements, or high-rise buildings? The bottom line–what is the life hazard in this area?

What is the effect of the weather? Is there mist, fog, rain, snow, extreme cold or heat, high or low humidity, an atmospheric inversion, or high winds? What are the direction and velocity of the wind? Has the cloud begun to dissipate or is it hanging lower than 150 feet, at which point it can be diluted or directed by a fire stream? Are these conditions favorable or unfavorable to control and thus evacuation?

What are the evacuation resources? Are there adequately trained personnel and ample resources readily available to conduct an orderly evacuation? Numerous people and vehicles may be required, especially if large numbers of nonambulatory evacuees must be moved.


If the decision is to evacuate, the next question should be, “How far should the evacuation extend?” Only minimal information is provided in the common reference books. The U.S. Department of Trans-portation`s Emergency Response Guidebook lists distances in feet for chemicals or mixtures indicating the initial isolation distance in feet for a small leak from a tank or a spill or leak from a drum or small container for 100-plus chemicals or mixtures. Also, it gives the initial evacuation distance in feet and then the downwind evacuation distance in miles for a large spill from a tank or from many containers or drums of these same chemicals and mixtures. Many associations have adopted standard recommended evacuation distances.

In some locales, computer modeling can predict where and how quickly a substance will move. Computer models can consider present terrain, buildings, and weather conditions not included in evacuation charts. Plotting past incident “cloud” (plume) patterns on local maps can also be done to estimate the needed evacuation areas. Informa-tion on clouds can be obtained from Nation-al Transportation Safety Board reports. A simple rule of thumb is to evacuate all civilians and all nonworking emergency response personnel for a distance of one mile. All operating personnel should be withdrawn for at least one-half mile when serious danger threatens.


The procedures for warning the civilian population are a critical part of evacuation. A well-planned evacuation message will prevent considerable confusion, lessen fear, and avoid panic. Develop a sample evacuation message in advance; a specific one can be tailored to the actual incident. The message must include several elements: the nature of the emergency and specific in-structions on where to go, when to leave, and which evacuation routes to use. Announcements that merely state “You must leave immediately” leave numerous unanswered questions. Radio and television stations can assist with evacuation messages. Someone in authority should monitor this emergency information to ensure its completeness and accuracy. If the evacuation will last for more than a few hours, the message should direct those who are ill to take their medications with them.

Residential districts require that two vehicles with public address (PA) systems announce an evacuation. The first one alerts residents; the second gives the message and instructions. The second vehicle must stop at each intersection and in the middle of each block and broadcast the message. Due to the closeness of homes and the noise from entertainment centers, vehicles may not be effective in alerting civilians. If using door-to-door warnings, those delivering the message should be easily recognized as authorized personnel so there is no doubt regarding the impending danger. Since people may refuse to leave their homes, evacuators need to know what authority they have to force people to leave for their own safety. Residential neighborhoods with single-family dwellings require two people per block to knock on doors. Small apartment building complexes require two people per building, whereas large apartment buildings require two people per floor. Since bullhorns, loudhailers, and vehicle-mounted public address systems are usually effective only to the fourth floor, the warning should be given on each floor in high-rise buildings by going door-to-door or by using a portable PA system. Helicopters with PA systems mounted toward the ground can also be used. To warn people rapidly and effectively, the delivery system must be planned in advance.


The evacuated areas should be marked. When going door to door, it is good to leave three-part evacuation tags consisting of an evacuation announcement to be left on the premises, instructions for the evacuee, and a third portion with the name or address and where the occupants were going. This record allows the evacuation control center to keep track of where people are routed. This is extremely important when separated families attempt to reunite. People returning from work searching for their spouses and children can be spared considerable grief if they can be directed to the proper evacuation center. Evacuation centers should keep a roster of evacuees who have arrived.

Schools should not be evacuated by simply dismissing the children. They will either try to go home or to the incident site be-cause of the excitement. Neither place is acceptable. Children should be transferred to an evacuation center until they can be reunited with their parents or safely re-turned to their school for dismissal.

Once a block or building has been cleared, mark the sidewalk with chalk to indicate the evacuation has been completed. It may be better to mark available utility poles to indicate a completed evacuation because these markings are visible at night, in inclement weather, and from vehicles. Banner or reflective tape also can be used for this marking.


Numerous evacuees with special needs must be considered in planning. They include those who do not want to leave their homes, the disabled, the extremely old, and the very young. Identify those who will need assistance during the evacuation. Anticipate the concerns that will arise, such as, Will our house be looted, or will it be exploited? Be prepared for the never-ending question, When will we go home?

Transportation problems include finding and moving those who cannot drive or do not have vehicles, finding enough vehicles to transport those who must be moved, minor traffic accidents, traffic jams, obtaining fuel for those who desire to drive themselves, and clearing accidents or abandoned vehicles from evacuation routes.


One of the major decisions at an incident involves evacuating patients in institutions, which is complicated by the fact that the decision must be based on the potential hazard. If the decision is delayed until the evacuation is unavoidable, there will be insufficient time to safely remove the patients or occupants. If the institution is evacuated and the hazard does not reach the facility, others will second-guess the IC and question the decision. On the other hand, if the evacuation is not made and the hazard reaches the institution, the IC will be criticized for not taking enough precautions. The IC cannot win either way.

Hospitals and nursing homes present severe evacuation problems. Multiple buses or ambulances may be necessary. Patients will need assistance boarding these vehicles. Medical records, medications, and critical medical equipment will also need to be transported with patients. Devices such as incubators will need power sources. Since hospital plans normally do not include evacuation, patients should be given as much lead time as possible to prepare. Physicians may need to check their patients before and after the move and also provide instructions to the staff of the receiving hospital. Dis-charging large numbers of patients to re-duce the evacuation problem may cause huge traffic jams around hospitals, further hindering the evacuation.


Once an evacuation is complete, the area must be secured until people are allowed to return. As the temporary displacement continues, tension will increase and individuals will attempt to return to their homes for a number of reasons. Discourage reentry until all hazards have been removed and proper information on what to do on returning has been disseminated to all evacuees. Utilities must be returned to service, roadways cleared, and a safe environment provided. Critical incident stress debriefings should be provided to prepare everyone for any loss of family, pets, and property they may experience.

Plan for controlled orderly evacuations, taking into consideration people`s reactions to stress so they can overcome their fears of a mass evacuation. Remember, when it comes to an evacuation, a great deal must be accomplished quickly and safely for it to be successful. n

GENE P. CARLSON, a fire education and training specialist, is director of international marketing of Oklahoma State University`s Fire Protection Publications, representing IFSTA nationally and internationally. Carlson is a member of various committees of the National Fire Protection Association and the International Association of Fire Chiefs. He served on the staff of the National Fire Academy, the University of Maryland Fire and Rescue Institute, and the University of Illinois Firemanship Training Program.

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