ERG2024 Glossary

ERG2024 Glossary, page 371GLOSSARY Adsorbed gas A gas which sticks (adsorbs) to the surface of a solid and porous material (such as activated charcoal) contained within a metal cylinder. This results in an internal cylinder pressure of less than 101.3 kPa at 20°C (14 psi at 68°F) and less than 300 kPa at 50°C (43 psi at 122°F). These pressures are much lower than those of conventional cylinders containing compressed or liquefied gases. AEGL(s) Acute Exposure Guideline Level(s), AEGLs represent threshold exposure limits for the general public after a once-in-a-lifetime, or rare, exposure and are applicable to emergency exposure periods ranging from 10 minutes to 8 hours. Three levels AEGL- 1, AEGL-2 and AEGL-3 are developed for each of five exposure periods (10 and 30 minutes, 1 hour, 4 hours, and 8 hours) and are distinguished by varying degrees of severity of toxic effects; see AEGL-1, AEGL-2 and AEGL-3. AEGL-1 AEGL‑1 is the airborne concentration (expressed as parts per million or milligrams per cubic meter [ppm or mg/m3]) of a substance above which it is predicted that the general population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic, non‑sensory effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure. AEGL-2 AEGL‑2 is the airborne concentration (expressed as ppm or mg/ m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience irreversible or other serious, long‑lasting adverse health effects or an impaired ability to escape. AEGL-3 AEGL‑3 is the airborne concentration (expressed as ppm or mg/ m3) of a substance above which it is predicted that the general population, including susceptible individuals, could experience life‑threatening health effects or death. Air-Reactive See “Pyrophoric”. Alcohol-resistant foam A foam that is resistant to polar chemicals such as ketones and esters which may break down other types of foam. BLEVE Boil over Boiling Liquid Expanding Vapor Explosion A sudden increase in fire intensity associated with the expulsion of burning flammable liquid caused by the boiling of water that has accumulated in the bottom of a tank car. Page 369#

ERG2024 Glossary, page 372GLOSSARY Burn Refers to either a chemical or thermal burn, the former may be caused by corrosive substances and the latter by liquefied cryogenic gases, hot molten substances, or flames. Carcinogen A substance or mixture which induces cancer or increases its incidence. Category A An infectious substance that poses a high risk to the health of individuals and/or animals or public health. These substances can cause serious disease and can lead to death. Effective treatment and preventative measures may not be available. Category B An infectious substance that poses a low to moderate risk to individuals and/or animals and/or public health. These substances are unlikely to cause serious disease. Effective treatment and preventative measures are available. CBRN Chemical, biological, radiological or nuclear agent. CO2 Carbon dioxide gas. Cold zone Area where the command post and support functions that are necessary to control the incident are located. This is also referred to as the clean zone, green zone or support zone in other documents. (EPA Standard Operating Safety Guidelines, OSHA 29 CFR 1910.120, NFPA 472). Combustible In this guidebook, a solid or liquid capable of burning but does not catch fire as easily as a flammable liquid. See “Combustible Liquid”. Combustible liquid Liquids which have a flash point greater than 60°C (140°F) and below 93°C (200°F). U.S. regulations permit a flammable liquid with a flash point between 38°C (100°F) and 60°C (140°F) to be reclassed as a combustible liquid. Page 370#

ERG2024 Glossary, page 373GLOSSARY Compatibility Group Control temperature Letters identify explosives that are deemed to be compatible. The definition of these Compatibility Groups in this Glossary are intended to be descriptive. Please consult the transportation of hazardous materials/dangerous goods or explosives regulations of your jurisdiction for the exact wording of the definitions. Class 1 materials are considered to be “compatible” if they can be transported together without significantly increasing either the probability of an incident or, for a given quantity, the magnitude of the effects of such an incident. A Substances which are expected to mass detonate very soon after fire reaches them. B Articles which are expected to mass detonate very soon after fire reaches them. C Substances or articles which may be readily ignited and burn violently without necessarily exploding. D Substances or articles which may mass detonate (with blast and/or fragment hazard) when exposed to fire. E & F Articles which may mass detonate in a fire. G Substances and articles which may mass explode and give off smoke or toxic gases. H Articles which in a fire may eject hazardous projectiles and dense white smoke. J Articles which may mass explode. K Articles which in a fire may eject hazardous projectiles and toxic gases. L Substances and articles which present a special risk and could be activated by exposure to air or water. N Articles which contain only extremely insensitive detonating substances and demonstrate a negligible probability of accidental ignition or propagation. S Packaged substances or articles which, if accidentally initiated, produce effects that are usually confined to the immediate vicinity. The maximum temperature at which a temperature-controlled substance can be safely transported. Above this temperature, self-accelerating decomposition or polymerization may occur. Page 371#

ERG2024 Glossary, page 374Control zones Criticality safety index (CSI) Cryogenic liquid Decomposition products Decontamination Dry chemical Edema ERPG(s) ERPG-1 ERPG-2 Page 372 GLOSSARY Designated areas at hazardous materials/dangerous goods incidents, based on safety and the degree of hazard. Many terms are used to describe control zones; however, in this guidebook, these zones are defined as the hot/exclusion/red/restricted zone, warm/contamination reduction/yellow/limited access zone, and cold/support/green/clean zone. (EPA Standard Operating Safety Guidelines, OSHA 29 CFR 1910.120, NFPA 472). A number value assigned to packages and overpacks containing fissile materials that limits the number of packages containing fissile materials during transportation. A refrigerated, liquefied gas that has a boiling point colder than -90°C (-130°F) at atmospheric pressure or is handled or transported at a temperature equal to or less than -100°C (-148°F). Products of a chemical or thermal break-down of a substance. The removal of hazardous materials/dangerous goods from personnel and equipment to the extent necessary to prevent potential adverse health effects. For more information, consult the “Decontamination” section. A preparation designed for fighting fires involving flammable liquids, pyrophoric substances and electrical equipment. Common types contain sodium bicarbonate or potassium bicarbonate. The accumulation of an excessive amount of watery fluid in cells and tissues. Pulmonary edema is an excessive buildup of water in the lungs, for instance, after inhalation of a gas that is corrosive to lung tissue. Emergency Response Planning Guideline(s). Values intended to provide estimates of concentration ranges above which one could reasonably anticipate observing adverse health effects; see ERPG-1, ERPG-2 and ERPG-3. The maximum airborne concentration below which it is believed nearly all individuals could be exposed for up to 1 hour without experiencing more than mild, transient adverse health effects or without perceiving a clearly defined objectionable odor. The maximum airborne concentration below which it is believed nearly all individuals could be exposed for up to 1 hour without experiencing or developing irreversible or other serious health effects or symptoms that could impair an individual’s ability to take protective action.#

ERG2024 Glossary, page 375GLOSSARY ERPG-3 The maximum airborne concentration below which it is believed nearly all individuals could be exposed for up to 1 hour without experiencing or developing life-threatening health effects. Evacuate Evacuate aims to protect as many people as possible by removing persons from inside a zone safely. If removal is too risky, sheltering-in-place can also be considered in this zone. Flammable liquid Flash point A liquid that has a flash point of 60°C (140°F) or lower. Lowest temperature at which a liquid or solid gives off vapor in such a concentration that, when the vapor combines with air near the surface of the liquid or solid, a flammable mixture is formed. Hence, the lower the flash point, the more flammable the material. Flooding quantities Hazard zones (Inhalation Hazard Zones) Minimum of 1900 L/min (500 US gal/min) of water. HAZARD Gases: LC50 of less than or equal to 200 ppm, ZONE A: Liquids: V equal to or greater than 500 LC50 and LC50 less than or equal to 200 ppm. HAZARD ZONE B: Gases: LC50 greater than 200 ppm and less than or equal to 1000 ppm, Liquids: V equal to or greater than 10 LC50; LC50 less than or equal to 1000 ppm and criteria for Hazard Zone A are not met. HAZARD LC50 greater than 1000 ppm and less than or ZONE C: equal to 3000 ppm. HAZARD LC50 greater than 3000 ppm and less than or ZONE D: equal to 5000 ppm. Please note: even though the term “zone” is used, hazard zones are not an actual area or distance. How zones are assigned is strictly a function of the lethal concentration 50 (LC50) of the product. For example, TIH Zone A is more toxic than Zone D. High expansion foam Foams that have a high expansion ratio (over 1:200) with a low water content. Hot zone Area immediately surrounding a hazardous materials/dangerous goods incident which extends far enough to prevent adverse effects from the released product to personnel outside the zone. This zone is also referred to as exclusion zone, red zone or restricted zone in other documents. (EPA Standard Operating Safety Guidelines, OSHA 29 CFR 1910.120, NFPA 472). IED See “Improvised Explosive Device”. Immiscible In this guidebook, means that a material does not mix readily with water. Page 373#

ERG2024 Glossary, page 376Improvised Explosive Device Isolate Large spill LC50 Mass explosion MAWP mg/m3 Miscible mL/m3 Mutagen Narcotic n.o.s. Noxious Page 374 GLOSSARY A bomb that is manufactured from commercial, military or homemade explosives. Isolate indicates a zone of no entry that applies to the public and first responders who are not equipped, trained, and prepared to mitigate the incident. A spill that involves quantities that are greater than 208 liters (55 US gallons). This usually involves a spill from a large package, or multiple spills from many small packages. Lethal concentration 50. The concentration of a material administered by inhalation that is expected to cause the death of 50% of an experimental animal population within a specified time. (Concentration is reported in either ppm or mg/m3). Explosion which affects almost the entire load virtually instantaneously. Maximum Allowable Working Pressure: The maximum allowable internal pressure that the tank may experience during normal operations. Milligrams of a material per cubic meter of air. In this guidebook, means that a material mixes readily with water. Milliliters of a material per cubic meter of air. (1 mL/m3 equals 1 ppm). An agent giving rise to an increased occurrence of mutations in populations of cells and/or organisms. Mutation means a permanent change in the amount or structure of the genetic material in a cell. A substance which acts as a central nervous system depressor producing effects such as drowsiness, narcosis, reduced alertness, loss of reflexes, lack of coordination, and vertigo. These effects can also be manifested as severe headache or nausea, and can lead to reduced judgment, dizziness, irritability, fatigue, impaired memory function, deficit in perception and coordination, reaction time, or sleepiness. These letters refer to “not otherwise specified”. The entries which use this description are generic names such as “Corrosive liquid, n.o.s.” This means that the actual chemical name for that corrosive liquid is not listed in the regulations; therefore, a generic name must be used to describe it on shipping papers. In this guidebook, means that a material may be harmful or injurious to health or physical well-being.#

ERG2024 Glossary, page 377GLOSSARY Organic peroxide An organic (carbon-containing) compound having two oxygen atoms joined together. Organic peroxides are thermally unstable chemicals. They may have one or more of the following properties: be liable to explosive decomposition; burn rapidly; be sensitive to impact or friction; react dangerously with other substances. Oxidizer A chemical which supplies its own oxygen and which helps other combustible material burn more readily. P See “Polymerization”. Packing Group The Packing Group (PG) is assigned based on the degree of danger presented by the hazardous material/dangerous good: PG I : Great danger PG II : Medium danger PG III : Minor danger PG See “Packing Group”. pH pH is a value that represents the acidity or alkalinity of a water solution. Pure water has a pH of 7. A pH value below 7 indicates an acid solution (a pH of 1 is extremely acidic). A pH above 7 indicates an alkaline solution (a pH of 14 is extremely alkaline). Acids and alkalies (bases) are commonly referred to as corrosive materials. PIH Polar Poison Inhalation Hazard. See “TIH”. A molecule in which one side of the molecule has a partial positive charge while another side has a partial negative charge. Examples includes alcohols and ketones. Polymerization A chemical reaction that often produces heat and pressure. Once initiated, the reaction is accelerated by the heat that it produces. The uncontrolled buildup of heat and pressure can cause a fire or an explosion, or can rupture closed containers. The letter (P) following a guide number in the yellow and blue sections identifies a material that may polymerize violently under high temperature conditions or contamination with other products during a transportation incident. It is also used to identify materials that have a strong potential for polymerization in the absence of an inhibitor due to depletion of this inhibitor caused by accident conditions. ppm Parts per million. (1 ppm equals 1 mL/m3). Page 375#

ERG2024 Glossary, page 378Protective clothing Pyrophoric Radiation Authority Radioactivity Refrigerated liquid Refrigerated liquefied gas Respiratory sensitizer Right-of-way Self-heating material Page 376 GLOSSARY In this guidebook, protective clothing includes both respiratory and physical protection. One cannot assign a level of protection to clothing or respiratory devices separately. These levels were accepted and defined by response organizations such as U.S. Coast Guard, NIOSH, and U.S. EPA. Level A: SCBA plus totally encapsulating chemical resistant clothing (permeation resistant). Level B: SCBA plus hooded chemical resistant clothing (splash suit). Level C: Full or half-face respirator plus hooded chemical resistant clothing (splash suit). Level D: Coverall, including structural firefighters’ protective clothing (SFPC), with no respiratory protection. SCBA: Self-contained breathing apparatus. For more information, consult the “Protective Clothing” section. A material which ignites spontaneously upon exposure to air (or oxygen). As referred to in GUIDES 161 through 166 for radioactive materials, the Radiation Authority is either a Federal, state/ provincial agency or state/province designated official. The responsibilities of this authority include evaluating radiological hazard conditions during normal operations and during emergencies. If the identity and telephone number of the authority are not known by emergency responders, or included in the local response plan, the information can be obtained from the agencies listed on the inside back cover. They maintain a periodically updated list of radiation authorities. The property of some substances to emit invisible and potentially harmful radiation. See “Refrigerated liquefied gas”. A gas which when packaged for transport is made partially liquid because of its low temperature. See “Cryogenic liquid”. A substance that induces hypersensitivity of the airways following inhalation of the substance. A defined area on a property containing one or more high- pressure natural gas pipelines. Material that may spontaneously ignite or generate heat on contact with oxygen (in air) after long periods of time (hours or days).#

ERG2024 Glossary, page 379Self-reactive material Shelter-in-place Skin corrosion Skin irritation Skin sensitizer Small spill Specific gravity Spontaneously combustible material GLOSSARY Material that is thermally unstable and produces heat upon decomposition, even without participation of air. People should seek shelter inside a building and remain inside until the danger passes. Sheltering-in-place is used when evacuating the public would cause greater risk than staying where they are, or when an evacuation cannot be performed. Direct the people inside to close all doors and windows and to shut off all ventilating, heating and cooling systems. In-place protection (shelter-in-place) may not be the best option if (a) the vapors are flammable; (b) if it will take a long time for the gas to clear the area; or (c) if buildings cannot be closed tightly. Vehicles can offer some protection for a short period if the windows are closed and the ventilating systems are shut off. Vehicles are not nearly as effective as buildings for in-place protection. The production of irreversible damage to the skin following the application of a test substance for up to 4 hours. The production of reversible damage to the skin following the application of a test substance for up to 4 hours. A substance that will induce an allergic response following skin contact. A spill that involves quantities that are 208 liters (55 US gallons) or less. This generally corresponds to a spill from a single small package (for example, a drum), a small cylinder, or a small leak from a large package. Weight of a substance compared to the weight of an equal volume of water at a given temperature. Specific gravity less than 1 indicates a substance is lighter than water; specific gravity greater than 1 indicates a substance is heavier than water. In this guidebook, a spontaneously combustible material means a pyrophoric (air-reactive) material or self-heating material. Refer to each term in the glossary. Page 377#

ERG2024 Glossary, page 380GLOSSARY Straight or solid streams Method used to apply or distribute water from the end of a hose. The water is delivered under pressure for penetration. In an efficient stream, approximately 90% of the water passes through an imaginary circle 38 cm (15 inches) in diameter at the breaking point. Hose solid streams are typically created by passing water through a non-adjustable bore tip. On the other hand, hose straight streams originate from fog nozzles that are dialed into a straight stream. Hose (solid or straight) streams are frequently used to cool tanks and other equipment exposed to flammable liquid fires, or for washing burning spills away from danger points. However, these streams will cause a spill fire to spread if improperly used or when directed into open containers of flammable and combustible liquids. Thermal runaway A chain reaction that leads to a violent release of stored energy and flammable gas. This reaction can spread to other batteries or combustible materials that are nearby, which could lead to a large-scale thermal event with severe consequences. TIH Toxic Inhalation Hazard. Term used to describe gases and volatile liquids that are toxic when inhaled (same as PIH). These materials pose a known hazard to human health during transport or is presumed to be toxic to humans because of animal-based studies. V Saturated vapor concentration in air of a material in mL/m3 (ppm) at 20°C and standard atmospheric pressure. Vapor density Weight of a volume of pure vapor or gas (with no air present) compared to the weight of an equal volume of dry air at the same temperature and pressure. A vapor density less than 1 (one) indicates that the vapor is lighter than air and will tend to rise. A vapor density greater than 1 (one) indicates that the vapor is heavier than air and may travel along the ground. Vapor pressure Pressure at which a liquid and its vapor are in equilibrium at a given temperature. Liquids with high vapor pressures evaporate rapidly. Viscosity Measure of a liquid’s internal resistance to flow. This property is important because it indicates how fast a material will leak out through holes in containers or tanks. Page 378#

ERG2024 Glossary, page 381GLOSSARY Warm zone Water insoluble Water-Reactive Material Water-sensitive Water soluble Water spray (fog) Area between Hot and Cold zones where personnel and equipment decontamination and hot zone support take place. It includes control points for the access corridor and thus assists in reducing the spread of contamination. Also referred to as the contamination reduction corridor (CRC), contamination reduction zone (CRZ), yellow zone or limited access zone in other documents. (EPA Standard Operating Safety Guidelines, OSHA 29 CFR 1910.120, NFPA 472). A substance that does not easily dissolve in water. In this guidebook, a material which produces a large amount of toxic gas when it comes in contact with water. Substances which may produce flammable, toxic and/or corrosive decomposition products upon contact with water. A substance that easily dissolves in water. Polar substances are generally soluble in water. Method or way to apply or distribute water. The water is finely divided to provide for high heat absorption. Water spray patterns can range from about 10 to 90 degrees. Water spray streams can be used to extinguish or control the burning of a fire or to provide exposure protection for personnel, equipment, buildings, etc. This method can be used to absorb vapors, knock-down vapors or disperse vapors. Direct a water spray (fog), rather than a straight or solid stream, into the vapor cloud to accomplish any of the above. Water spray is particularly effective on fires of flammable liquids and volatile solids having flash points above 37.8°C (100°F). Regardless of the above, water spray can be used successfully on flammable liquids with low flash points. The effectiveness depends particularly on the method of application. With proper nozzles, even gasoline spill fires of some types have been extinguished when coordinated hose lines were used to sweep the flames off the surface of the liquid. Furthermore, water spray carefully applied has frequently been used with success in extinguishing fires involving flammable liquids with high flash points (or any viscous liquids) by causing frothing to occur only on the surface, and this foaming action blankets and extinguishes the fire. Page 379#