A Prepared Approach to Hazardous Material Incidents

A Prepared Approach to Hazardous Material Incidents


Experienced first responders to hazardous materials incidents tend to use similar, basic procedures and strategies. Being aware of these practices can mean the difference between successful control of an incident and a complete disaster situation.

To ensure control of a hazardous materials incident response effort, vigilance and discipline must be maintained by first-in units. To control the scene, nonessential people are kept out of the area, approach and size-up are done with a minimum of personnel, additional forces are committed only as necessary, and reserve personnel are kept on remote standby.

Apparatus are positioned to permit retreat, and kept out of sprays, runoffs, residue and vapor clouds. Experienced responders recognize that certain vapors (such as oxidizers) entering a carburetor can make an internal combustion engine take off like the space shuttle, while other vapors (chlorine, for example) will exclude oxygen and stall the engine. A fire engine that can neither pump water nor be driven to safety becomes a substantial liability.

Lack of fear at a major hazardous materials incident may well mean the fearless person just does not understand the situation. Experienced responders freely admit some hazardous materials can be scary. They wear gloves, their face shields are down and bunker gear is tightly closed. SCBA are donned at once, and safety lines are used as necessary. For each man inside the contamination (hot) zone, there is a man suited up on the outside ready to go. As responders learn the exact circumstances of an incident, they may back off from the initial level of personal protection. Inexperienced responders may call such stringent safety measures overkill; experienced responders use the terms vigilance and discipline, and warn each other to beware of the guy who thinks he is immune.


Experienced responders observe certain basic disciplines. They engage in detailed, pre-incident planning in order to develop and implement a systematic approach to maximize effective utilization of available resources. Such prior planning serves to identify unknowns, establish productive relationships, minimize variables and identify responsibilities.

Planning attempts to identify what needs to be done and helps to establish a framework for getting the job completed. Hazardous materials pre-incident planning efforts often consider these specific components: development of a hazard analysis; creation of a resource inventory; accumulation of product information; implementation of a response capability; provision of training; and development of protocols or standard operating procedures to guide response personnel on the scene.

Experienced responders learn mechanical environment and containerization used at identified hazardous materials facilities in order to know’ ahead of time mechanical/electrical shutoff locations and operations. Before attempting to patch or plug a leak, experienced responders first check for shutoff valves, electrical circuits or other means of control built into the system that someone may have failed to activate. Too many times people have tried to patch leaks or plug pipes when they could have walked 20 feet and thrown a switch or turned a valve. Experienced responders do not extinguish flammable gas fires until the flow can be stopped, knowing only too well that if the fire is extinguished before the flow is stopped, vapors can spread unseen throughout the area and easily reignite.


Experienced responders utilize the expertise of facility personnel and other experts in order to better understand the systems and materials involved in an incident. They maintain call lists of persons and organizations with particular capabilities, obtain prior commitments for assistance during an emergency, and identify alternative sources of supply. Help is called for immediately if a need is even suspected. Experienced responders obtain and train with specialized tools, equipment and materials, and have access to a variety of patching and plugging devices.


The initial size-up or evaluation of a hazardous materials incident is a crucial component of effective response. Size-up includes detection and identification of hazardous materials; evaluation of fire, explosion, reaction, and health and environmental hazards and impacts; rescue; request for outside assistance; estimation of danger areas; definition of potential secondary emergencies; identification of critical exposures; initiation of evacuation if called for, and determination of proper suppression and control activities.

Because hazardous materials normally become extremely dangerous only when released from some type of containerized environment, the ability to patch/plug leaks in a wide variety of containers has assumed great importance.

A number of hazardous materials response teams around the country have assembled necessary equipment and materials that allow them to control numerous types of leaks in literally hundreds of different types of containers. Experienced responders repeatedly stress how often they use common, ordinary tools and materials in controlling hazardous leaks. They point out that they do not try for an “ultimate patch/’ but rather work to temporarily stop the flow—or at least reduce the flow. Response personnel often work under frightening conditions, but their basic stock-in-trade is the ability to temporarily patch/plug any leak in any vessel, tank, cylinder or drum.


Experienced responders develop preprinted forms to help ensure that necessary information is obtained for use in pre-incident planning, on-scene operations, reporting and evaluating. Reliable, specific information is a critical factor in response to hazardous materials incidents. There are so many chemicals, interests, conditions and variables potentially involved at an incident that a standard format for acquiring information is considered a necessity by many responders. Worksheets/checklists are one way in which response personnel seek to gather the maximum possible amount of pre-incident planning information; ensure that the right questions are asked and answered; obtain and record information from actual experience to aid in training, experience evaluation and future planning; maintain incident vigilance and discipline; refrain from underestimating the potential seriousness of an incident; maximize safety of response personnel; secure reliable data for reports and possible testimony; quickly determine the identity and characteristics of the products involved; and ensure thoroughness in responding to incidents.

Spell it out

Experienced responders ensure correct reporting of basic information such as chemical names because they know one misspelled letter or an incorrect pronounciation can dictate an incorrect response. The following pairs of chemical names sound alike, but the proper response can be vastly different.

Acetyl iodide/acetaldehyde

hexa ne/hexene

isopropanol / isopropeny 1

ethanol / methanol

ethyl alcohol /methyl alcohol

phosphorus trichloride/phosphorus tri fluoride

benzol/benzoyl phenol/phenyl

propionyl chloride/propyl chloride thionyl chloride/vinyl chloride

To ensure proper transmittal of chemical names, responders spell it out and use the DOT four-digit identification number of the STCC (49-series) seven-digit code to be sure a chemical name is understood correctly.

Know chemical properties

With liquefied, compressed gases, responders are aware of liquid-to-vapor expansion ratios. That is, they recognize that if a tank car of chlorine viewed as one volume of liquid ruptures, it will release 470 volumes of vapor; 470 tank cars would be required to contain the amount of chlorine vapor released from one ruptured tank car of liquefied chlorine.

Plan ahead

List resources

Size up accurately

Understand chemical properties

Keep current checklists

Respect hazards

Spell the chemicals correctly

Tell the story responsibly

With gas/vapor, experienced response personnel immediately determine its vapor density in order to understand proper monitoring and control procedures. Air has a vapor density of 1.0; a product with a vapor density of less than 1.0 (anhydrous ammonia at 0.6) is lighter than air and will tend to rise. A product with a vapor density of greater than 1.0 (propane at 1.6) is heavier than air and will tend to settle, finding its way into low spots such as trenches, depressions or cellar holes. Thus, monitoring procedures for propane are significantly different than monitoring procedures for anhydrous ammonia.

Many combustible gases are heavier than air and will tend to seep into low spots or travel at low’ levels for a considerable distance to a source of ignition and flash back. Experienced responders faced with combustible gases perform continuous monitoring at various locations. Standing in one spot and taking a few samples will not provide the necessary protection. When combustible gases are potentially present, many responders assign one person to continuously move throughout the area taking repeated readings with particular attention to low’ spots such as trenches, slopes and depressions.

In dealing with liquids, experienced responders immediately identify the specific gravity of the product and determine whether the product is soluble or insoluble in water. Water has a specific gravity of 1.0; a liquid with a specific gravity of less than 1.0 that is insoluble in water will tend to rise to the surface of water and float. A liquid with a specific gravity of greater than 1.0 that is insoluble in water will tend to “sink.” A liquid that is soluble will mix with water. Such considerations determine if and how a product can be removed from water such as a flowing stream or fire fighting runoff.

Experienced responders tend to train, practice, work and learn as a team and come to depend on each other. It just doesn’t work if someone has to be told to pick up the shovel, dig the hole and throw the dirt over there.

Hazard awareness

Experienced responders develop an acute awareness of potential secondary and tertiary hazards. They expect that something will go wrong. They expect to run out of air. They expect incorrect advice/information or misinformation, for they know bystanders want to be helpful or industrial personnel may want to keep an incident low-key. They have tremendous respect for tire fires, wheel rim holders, “empty” tanks, shock-sensitive materials, alternative fuels in vehicles, saddle tanks on propane delivery trucks and fumigants used in boxcars containing agricultural products.

Experienced responders know that many times safety devices on tank vehicles have been altered and that innocuous rail cars can carry significant quantities of diesel, gasoline or propane to run a reefer unit. They look for a passing train to crush them, a snapping cable to decapitate them, or a wrecker operator to yank a tank over and watch it bounce.

Experienced responders assume any liquid pooled on the ground is much deeper and more dangerous than it appears. They are aware of the phenomena known as synergistic effect, whereby the joint action of chemicals working together can increase the effectiveness of each, causing far greatear danger than if each chemical could be dealt with separately.

Reactivity is another consideration of experienced responders—will the patching/plugging material or device being used react with the hazardous material? Incompatibility is considered—are certain chemicals dangerously reactive if mixed accidentally?

Experienced responders are acutely aware of potential contamination of personnel, clothing and equipment, particularly when working with oxidizers and pesticides. They immediately shower with fire hoses if serious contamination is even suspected, require immediate return to base of possibly contaminated personnel fora shower with soap and water, remove contaminated clothing and equipment, demand that clothing and equipment suspected of being contaminated not be used again until decontamination has been completed, and discard clothing and equipment if decontamination cannot be adequately performed. Spare clothing maintained on the response vehicle is cheap insurance. Experienced responders take care to recognize symptoms of chemical exposure (such as from pesticides) even though such symptoms may be nearly identical to symptoms of flu, heat prostration or smoke inhalation.

When exposure to pesticides is even suspected, experienced responders get the label and send it along with potentially contaminated persons in order to alert the examining physician. Mouth-to-mouth resuscitation is never given to persons known to have suffered contamination by pesticides or hazardous materials such as freon.

Experienced responders know water can make many pesticides ultradangerous; that many pesticides can readily pass through the skin without causing any sensation or providing any warning; that solvents in some pesticide solutions can be absorbed even through rubber boots or other protective clothing; that massive prolonged exposure to a low toxicity pesticide can be as damaging as minor short-term exposure to a highly toxic pesticide; and that a number of pesticides are cholinesterase inhibitors, affecting the ability of nerves to transmit impulses so that a responder will not realize he is being poisoned.


Experienced responders recognize that the media can help them or hurt them, and are aware of the effect their actions or lack of action can have on media coverage of an incident. Their approach to the media is facts, not fantasy. They use only one spokesman. The person assigned duties of media liaison must have the authority and knowledge to know what is going on at all times.

The media may well be an incident commander’s primary contact with the general public and should be viewed as a resource rather than a hindrance. Media assistance can be immediate and tangible if it becomes necessary to evacuate an area, close highways, maintain perimeter control, assure access to needed personnel through designated checkpoints, alert medical personnel, establish reception centers, or have the general public engage in acti ities necessitated by the emergency situation.

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