Hazardous-Materials Recognition

By 1990, there were over 10 million chemicals registered with the Chemical Abstract Service (CAS). Since that time, the CAS has registered an average of 50,000 new materials each month. Today, more than 5% of all cargo shipped in the United States is hazardous. With this in mind, many emergency responders consider hazardous-materials response to be a specialty topic area that they will rarely, if ever, encounter. In reality, emergency responders routinely encounter hazardous materials on a daily basis. The ability to recognize the presence of hazardous materials is critical to ensuring the safety of response personnel. This article is the first in an ongoing series that will address hazardous-materials issues relevant to first responders and EMS personnel.

What is a Hazardous Material?
     The U. S. Department of Transportation (DOT) classifies hazardous materials as "any substance or material in any form or quantity that poses an unreasonable risk to safety, health and property when transported in commerce." Obviously, the DOT definition focuses on hazardous materials in transportation. Similarly, the U.S. Environmental Protection Agency (EPA) looks at the impact of hazardous materials on the environment, and the Occupational Safety and Health Administration (OSHA) defines hazardous materials based on their workplace impact. With so many definitions floating around, determining what is hazardous or not can be confusing.

     A simple definition is that a hazardous material is any material that can cause harm. By using this straightforward definition, emergency responders will recognize the presence of hazardous materials based on the risk associated with their presence. For example, if responders recognize that blood has the potential for causing harm, they will take precautions to prevent contact with blood. Similarly, if they recognize the hazards posed by gasoline, they can take precautions to prevent exposure to gasoline.

Chemical and Physical Properties
     All hazardous materials are found in one of three states of matter: solid, liquid or gas. Materials may change from one to the other, based on temperature and air pressure. For example, water moves from a solid to a liquid at 32°F and to a vapor at 212°F. If a material goes straight from a solid to gas without passing through the liquid state, it has undergone the process of sublimation.

     Most materials exhibit a tendency to vaporize at normal temperatures. Those that are already gases at sea level possess vapor pressures of at least 760 mm/Hg. Materials that will not vaporize, like rock, have vapor pressures of 0 mm/Hg. All other materials have vapor pressures somewhere in between. The closer the vapor pressure is to 760 mm/Hg, the faster it will vaporize. This is important, because the speed at which a material vaporizes gives some indication as to how far and quickly a material may reach and harm a responder.

     Another property related to vapors is vapor density. Vapor density is simply a comparison of the weight of a vapor to the weight of air, with air being given the constant of 1. Vapors with vapor densities greater than 1 tend to sink, while those with vapor densities less than 1 tend to rise. Fortunately, there are only a few common gases that tend to float. They are: Methane, acetylene, illuminating gas (a mix of ethane and methane), nitrogen, hydrogen, ammonia, carbon monoxide, helium, diborane, neon and hydrogen cyanide.

     Similar to vapors, the weight of liquid is compared to water. Those materials with molecular weights less than water, with water having the constant of 1, tend to float; those with weights greater than 1 tend to sink.

Death Clog: Drain Mix Kills Illinois Man, Sickens Medics
     The December death of a Chicago-area man should remind EMS providers that danger can lurk anywhere-even in a quiet suburban kitchen.

     Gerald Carlton, 47, of Orland Park, IL, died on December 19 after he was overcome by toxic fumes produced when he mixed multiple products in an attempt to unclog his kitchen sink. Five paramedics and a paramedic student who came to his aid were hospitalized after exposure to the fumes.

     "This is a tragic accident," Orland Fire Protection District Chief Donald Bettenhausen told the Chicago Sun-Times. "It was a bad cocktail-a chemical cocktail."

     Carlton's sink had been stopped up for days, the newspaper reported, and he'd tried several products to open it. First it was Liquid-Plumr; then it was Rooto Professional Drain Opener, which is concentrated sulfuric acid. He may also have used Comet with bleach, according to police.

     When he applied the Rooto, however, a reaction started, and Carlton's son called 9-1-1. By the time medics arrived, Carlton was in cardiac arrest, and his son and wife were also feeling ill. Police reported the smell of chlorine in the home.

     EMS providers, believing they were responding to an asthma attack, did not wear masks when entering the home. In removing the occupants, Bettenhausen said, they too were exposed to the fumes. All were expected to recover quickly, as were Carlton's wife and son.-John Erich, Associate Editor

Where Hazardous Materials Are Found
     While some locations where hazardous materials are used or stored seem obvious, like chemical refinery facilities, most hazardous materials emergency responders encounter are hidden in plain sight. And although hazardous materials in businesses may be easier to spot, any house will provide a wide variety of hazardous chemicals. Most kitchens, garages, laundry rooms and basements contain cleaning supplies, caustic materials, flammable liquids, pesticides and poisons.

     Hazardous materials in transportation provide a unique challenge. While the chemicals being used at a refinery remain relatively constant, the hazardous materials moving through roads, rails, pipelines, planes and waterways change every moment. There are several clues that may help the responder recognize that hazardous materials are present.

     Placards consisting of a color, symbol and class number have been designated by the Department of Transportation for quantities of hazardous materials beyond threshold amounts. Some placards may also include a four-digit identification number and a division number that follows the class number. Figure 1 indicates the placards that may be commonly encountered by emergency response personnel.

     While placards provide a clue to the presence of hazardous materials, they are subject to human error.

     In addition to the placard system, the container shape can provide a clue to the quantity and material. Since matter is found in three distinct forms, solid, liquid and gas, the means for transporting these materials must be tailored to the form. Containers designed to carry solids range in size from boxes and bins to solid bulk rail cars and barges. When solids breach their container, the hazard tends to remain near the container unless the material is affected by weather, wind or water. If this occurs, the material may react or be transported away from the site.

     Liquids can be found either at room temperature or compressed. Liquids that are liquid at ambient temperature will seek to settle at the lowest point when they escape their container. They roll downhill and seek to vaporize, so the vapor pressure of the material becomes of great concern. Materials that are liquid at normal temperatures and pressures may be stored and shipped in many containers, including bottles, drums and tank cars.

     Compressed liquefied gas containers may fail violently. These materials are liquefied under pressure. As a result, breaches of the container may be violent or explosive. In addition, since these materials are compressed, they tend to expand greatly at ambient pressures and temperatures as they return to their gas state upon leaving the container. Common compressed liquefied gas containers include propane cylinders and trailers.

     When given the opportunity, gases exit their container and spread out. These materials, like liquefied gases, have a normal vapor pressure of greater than 760 mm/Hg. Materials that are in the gas state, whether liquefied or compressed, spread out over a wide area when released. These containers may also fail violently if exposed to stresses such as heat or damage. Compressed gas containers include acetylene and oxygen cylinders and tube trailers, which are simply large cascade systems.

     The ability of responders to rapidly recognize the presence of hazardous materials is instrumental in identifying potential risks from the materials, selecting personal protective clothing and determining incident priorities and tactics. Hazardous materials are widely distributed and used, and a basic understanding of them is necessary for a safe and effective response.

Dave Donohue has 25 years of emergency response experience, including 23 years responding to hazardous materials. He holds an MA in Public Administration with a major in crisis management and an MA in disaster science. He is currently a hazardous-materials training specialist in the Washington, DC, area.