BY WILLIAM BRIGDEN
In any emergency, responders must work around static factors. Taking into account the static factors helps you to determine if you should employ an offensive or defensive strategy or one of nonintervention. You must act quickly and methodically.
 Figure 1 |
What factors should be included in a complete assessment of a haz-mat incident? Although incidents may vary, some factors occur at every incident. Focusing on these points helps you recall the general fields of “need-to-know” risk-related information that will lay the foundation for all strategic and tactical decisions. This information also outlines and identifies safety concerns related to all personnel. You must use information that is as complete and as accurate as possible, and it must be continually monitored, updated, and assessed.
THE “MADDER” RISK ASSESSMENT PROCESS
The “MADDER” risk assessment process (Materials; Amount; Damage; Duress; Exposures; Response conditions) follows the flow of a hazardous-materials incident and helps guide you during the size-up. The process starts with the material and its hazards, follows the material’s movement through its release point away from its container out to where it will contact and harm exposures (Figure 1). An increase in the severity of any one of the fields will produce a corresponding increase in the hazard level for the responder for that incident. Not all of the MADDER fields will be needed at every incident.
Materials
The first step is to positively identity the material. Haz-mat technicians are trained to use more than one source when researching the properties to identify a hazardous material. You should question responsible personnel at the incident who might have information and compare that information with that obtained from other sources such as placards, container types, material safety data sheets (MSDSs), and shipping papers.
 (1) The energy released from a boiling-liquid, expanding-vapor explosion (BLEVE) propelled this LPG tanker several hundred yards and would have been deadly for anyone in the area. (Photos by author.) |
At some incidents, it may be difficult, if not impossible, to identify the product. In some cases, several materials might be involved, and it would be difficult to determine what the materials are, how they will interact with each other, and the effect of the final product on humans.
You also need to be cautious of complacency that might set in when you respond to recurring calls, not unlike back-to-back false alarms to a college residence on a Saturday night. The hazardous materials equivalent is the all too popular “suspicious powder” call.
 (2) In this incident, the fire department and specialists from the trucking company found damaged unloading piping and a small leak in one of the dome covers. |
• Energy. The identified material can be viewed as energy or matter. Energy refers to the form of the hazardous materials or the conditions they can create. Energy is found in explosives, pressure in systems or vessels, reactive materials, and the overpressure of a containment system. In every situation, you must assess whether a probable energy release situation exists. Energy releases are the most dangerous conditions for responders; avoid them at all costs. If there is a probable energy release, there is no way responders can protect themselves. In this case, nonentry or withdrawing from the area is the only option. This may appear to be a “yes” or a “no” type of situation; however, arriving at a decision can be difficult.
You should also identify sources capable of producing energy, which include electrical hazards, unstable containers, large objects, or containers that may collapse.
Matter may be chemical, biological, or radiological. This article deals with the characteristics of chemicals.
Among the properties to assess are the following:
• Flammability. The red placard or label indicates a flammable material. When reviewing documentation, look for the flashpoint, ignition temperature, and flammable range. Using a combustible gas meter will provide direct readings and is a necessary tool at incidents involving a flammable substance. If the readings indicate dangerous levels, focus on removing the ignition sources and reducing the vapors by ventilation or vapor suppression.
• State and vapor pressure. Chemicals must contact a body to cause harm and, because they are matter, they must move physically. The physical state determines how a chemical will move or contact exposures. Gases will “chase you around the room” because of their ability to move more freely than the other states. Gases can affect a larger area and create concentrated levels in enclosed spaces. The gaseous form of a material is more dangerous than the other states of the same material because it can be readily inhaled and it can move.
Vapor pressure refers to a substance’s ability to produce vapors. Materials with high vapor pressures produce vapors and pose hazards similar to those of gaseous products. Liquids with low vapor pressures create less airborne product as vapors and generally require closer contact before harm occurs. Solids and their hazards typically have even more of a tendency to stay where placed. Solids reduced to an extremely small size (such as dust) will move in the same manner as gases.
• Corrosivity. Materials with black-and-white class 8 placards or labels indicate a corrosive material. A corrosive can be a solid, liquid, or gas form that burns, irritates, or destructively attacks organic tissues by chemical action. Corrosive materials can be identified on an MSDS, by information resources, or by the use of pH paper.
• Toxicity. It refers to the effects the product will have on unprotected humans. Information is available from various toxicological values found in documentation. Threshold limit value (TLV), short-term exposure limit (STEL), and immediately dangerous to life and health (IDLH) values indicate the relative hazard of a product. The lower the number, the more toxic a product is.
• Solubility and miscibility. These properties indicate if a product will mix with water and how well. A product that does not mix with water is termed “insoluble” or “immiscible.” In these cases, the specific gravity of the substance will indicate if the product will float or sink in water. This information helps to decide decontamination needs and will assist in determining how to best control a spill in a waterway.
• Vapor density. It tells us how heavy a material is in air and how and where to monitor for the chemical. It also provides data for estimating where the vapors of a material will accumulate or where a released gas cloud will go if using a computer plume dispersion model.
Identifying the material and its hazards allows you to understand the root of the problem.
Amount
Once the material and its hazards have been determined, you need to evaluate the amount of the product. This refers to how much product is in the container, how much has leaked out of the container, and how fast the product is leaking. In some cases, this information will be available from a responsible person on-site, or it may require evaluating the container or damaged closure.
Amount refers also to atmospheric levels. If a release presents a gaseous or vapor hazard, determine the airborne amounts or concentrations to decide zoning and evacuation needs. However, when determining airborne levels, ensure that the instrumentation you are using is accurate for that material.
The three amount-related variables allow you to classify the spill as static or dynamic and to determine the strategic “yes” or “no” actions of intervention/nonintervention. Tactics for a broken bottle that has released its entire contents should be directed at dealing with the effects of the release, not trying to slow or stop the leak. On the other hand, a damaged valve on a large, full facility tank may require dealing with the effects of the spill as well as directing actions at isolating the leak.
Gaining this information will also help in the all-encompassing risk assessment question, “Is what we are doing necessary?” Going to the trouble of offensive operations for a container that will be nearly empty may not be as good an option as simply performing defensive operations of confining and controlling the runoff.
Damage
Estimating the “behavior of a container and its contents” is addressed in National Fire Protection Association (NFPA) 472, Standard for Professional Competence of Responders to Hazardous Materials Incidents, 1997, and determines where the incident is going and the means for controlling it.
Two things are going on between the container and the material inside: The container is trying to keep the material inside, and the material inside the container is trying to escape. Solids, liquids, vapors, and gases all put pressure on the containment system; once a hole exists, the material will use it to escape. If the material succeeds in escaping or if the container fails to hold the material, you have a problem.
The container’s job is to contain the product; any damage will affect this. The way a container is made determines how it will fail. Options for handling the incident will be based on considerations such as whether the container is of single-shell or double-jacket construction and the type of material used in its construction-glass, cardboard, plastic, or steel. Attachments, fittings and closures, relief valves, and piping configuration must also be considered. NFPA 472-trained operations- and technician-level responders should be familiar with various containment systems and may be able to gain valuable information from the incident. Responders can also question on-site specialists with specialized container knowledge. With this information, responders can more accurately assess the damage to the container.
The NFPA lists four general types of container damage-possible releases: No damage, no release; No damage, release; Damaged, no release; and Damaged, release.
The type and level of damage dictate the options and determine whether responders can control or fix the problem. Typically, it is difficult to repair a damaged container. Knowing how a container is releasing its contents indicates how and to what extent responders will become contaminated and thus the levels of personal protective equipment and decontamination needed.
• Duress. Hazardous materials want to escape. A containment system is always under some kind of duress, stress, or internal pressure. Whether the material weight of a dry solid pushing out at the bottom of a hopper, the liquid head pressure on an unloading valve in a gasoline truck, the vapor pressure in a plastic gas can on a hot summer day, or the pressure on the valve of a chlorine cylinder, all products produce some sort of internal force on their containment system. Duress refers to the degree to which the product is trying to get out of the container.
Following a derailment, railroad personnel will attempt to identify tank car contents and determine the pressure in the rail cars. The damage to the cars in a derailment affects the tank’s integrity, and the internal pressure of the tank car is a critical factor. Why are we so concerned about the duress of a container? In a worst-case scenario, the internal force produced by the container’s contents can cause an overpressure if the container is weakened, resulting in a catastrophic failure of the containment system.
This internal force will also affect responders’ ability to control or fix a problem. For example, a hole in a nonpressure metal drum needs only a plug or patch strong enough for the head pressure of the liquid. The pressure in a gas cylinder requires repair techniques capable of maintaining a much higher pressure. Knowing the pressure can help you estimate the amount of product that can be released and the general speed at which a failure can occur. Exposures will suffer greater damage with an instantaneous release than a slow, prolonged one. All of this information will also provide the final piece of the puzzle in predicting the likely outcome of a container and its contents.
Exposures
This step assesses everything the hazardous material will touch and harm. The four potential exposures in their general order are loss of life, damage to the environment, damage to property, and systems disruptions. Responders strive to protect these exposures and to establish an acceptable level of risk for personnel.
• Life. Life should always be the highest priority; responders will risk a great deal to save a victim in a dangerous situation. However, it is important to recognize that a responder’s life should be risked for a savable life.
In recent history, terrorism raised concern and discussion pertaining to the necessity to contain water that had been contaminated after decontaminating victims. Containing the water would mean spending valuable time constructing protective measures for the environment before entering an area to rescue humans in danger of losing their lives. The Environmental Protection Agency resolved the issue. It issued a bulletin stating that emergency decontamination of humans was to be put before environmental concerns, that the priority of life takes precedence over all other priorities.
• Environment. Environmental issues are always a serious concern; in fact, agencies, groups, and legislation have been created to support this priority. Identify and evaluate any short-term environmental concerns as quickly as possible. Consider also any long-term environmental damage that may occur from contamination of the soil or groundwater. Review the tactics you use to mitigate the incident from the perspective of any potential environmental damage they may cause.
• Property. Significant property losses or damage (catastrophic damage to the largest employer in a small town or the loss of a significant historic landmark, for example) may seriously affect the entire community. There may also be potential monetary losses to property, such as in the case of a leak that shuts down a wafer fabrication area in a semiconductor manufacturing plant or a rail line that is closed because of a derailment. Such situations create a loss of tens of thousands of dollars of revenue per hour. On the other side, public safety officials may believe it necessary to wait to reopen areas or commence repairs or remediation. In such situations, it is important to strike a balance and recognize the areas of concern for all affected parties.
• Systems disruptions. Community infrastructures, such as critical power lines, transformer stations, communication infrastructure, utility systems, or major transportation routes, may be disrupted. These disruptions raise serious concerns and often have a long-ranging ripple effect. The final cost of a system disruption may be difficult to assess and sometimes can only be determined after the fact. You must try to anticipate the effects the incident will have on the affected systems.
Many hoax emergencies, such as suspicious packages, force emergency responders unable to properly assess the situation to create systems disruptions as a result of their response to the incident. In many cases, creating system disruptions by closing the facility, preventing work, and producing financial losses are objectives the individual responsible for the hoax was attempting to accomplish. Responders should evaluate such decisions carefully.
Response Conditions
This variable takes all of the other factors-Material, Amount, Damage, Duress, and Exposures-into consideration. Any incident can vary if the Response conditions are changed.
• Inside, outside. The greatest variable in response conditions involves the immediate area in which the incident occurs. A spill can occur inside or outside.
 Figure 2 |
Inside refers to any structure or area that creates confinement that will concentrate the effects of the release. The effects an inside release can have on the outcome of an incident can be illustrated using the example of a leaking container of gasoline. A one-gallon spill of gasoline in a parking lot requires an evacuation of several yards around the spill. If an ignition source is present, the material will flash and ignite. The same spill inside could necessitate an evacuation of the entire structure and, if ignited, can demolish an entire building. Some responders, such as facility or railroad responders, generally may deal with one type of situation. However, fire service personnel responding to these incidents must be able to distinguish between the two scenarios as quickly as possible
• Time of day. Time of day can affect the number of people in a given area. An incident during rush hour on a major highway or between 9 a.m. and 5 p.m. at a plant increases the number of people affected. The time of day an outside release occurs may change daytime or nighttime conditions. This can be seen in the Emergency Response Guidebook: The Table of Initial Protection and Protective Action Distances indicates larger zones for nighttime releases.
• Location. Similar to time of day, the location of the incident determines the number of people affected and the potential harm. Incidents in a remote area would affect fewer people than one in an urban area and would also require fewer resources than a heavily populated area, where more resources may be needed for a larger evacuation. The incident’s location may also affect access to the site. If the incident is in a remote area without roads, the priority may be to build or gain access before operational activities can commence. Lack of water might also be a problem in remote situations, as might a delay in arriving at the scene. Responders may consider gaining information en route and developing a method for achieving this. When there is a time delay, responders should attempt to determine what the probable or expected condition of the incident will be on their arrival.
• Weather. Weather conditions generally affect outside spills only. Wind direction, speed, and stabilization affect the direction, distance, and dispersion rate of the release, dictating control zones and evacuation. Additionally, an air inversion or high humidity may inhibit the dispersion of vapors and cause them to be concentrated or held near the ground, creating a greater hazard in the immediate vicinity of the release. Temperature should also be considered because of its effect on vapor pressure and flammability. Some chemicals react adversely with water and precipitation. This can change product stability or may work to spread the product. Finally, as with weather conditions, responders should pay special attention to the potential for weather changes.
• “Friends” and “foes.” Some conditions create difficulties and add concerns to any incident. A hazardous materials team dealing with a leaking poison tank will have added problems if the accident occurs close to an environmentally sensitive bird sanctuary, for example. Other “foes” might include a spill or runoff near a waterway (you would have to prevent a release into a body of water), ignition sources that cannot be controlled (the incident could escalate at any moment); and fire-impinged, unstable containers, and chemical incompatibilities (they make it difficult to predict what may happen and to devise a mitigation plan).
Operating sprinklers or fire suppression systems have assisted emergency responders in countless situations. “Friends” for the hazardous-materials responder may include facility spill and engineering controls designed to manage the release of a hazardous material. In-house detection systems and remote shutoffs for product lines enable you to control a release from a distance. Evaluate these “friends” and “foes,” and include them in your size-up.
• • •
Emergency response entails working in uncontrolled and potentially dynamic situations. Incomplete information, time constraints, and the need to make immediate and important decisions are the conditions of the emergency workplace. Because emergencies seldom are identical, you must assess all hazards. Using a process that provides a framework for identifying relevant factors, such as MADDER, helps you to consistently gather information and make a complete risk assessment. ■
■ WLLIAM BRIGDEN is a 20-year veteran of the fire service, a hazardous-materials technician, and an acting safety officer with the Ottawa Fire Services. He has a fire technology diploma from the Ontario Fire College and has worked in the hazardous-materials field for nearly 15 years, instructing fire service personnel and private industry teams. Brigden has developed hazardous-materials training programs and regularly presents hazardous materials workshops on risk assessment, size-up, clandestine drug labs, and instrumentation.
