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A	Abbreviation for ampere(s).
A end	The end opposite the handbrake or "B" end of the tank car.
A/B switch	A switch that selects one of two inputs (A or B) for routing to a common output.
A/B/C/D sides	At a building fire, the sides of buildings are identified by ABCD sides, with side A being the front of the building, and sides BCD being named around the building in a clockwise fashion. This helps maintain clear communication on the fireground for location of assignments or firefighters.
A/C	An abbreviation for air conditioner or air conditioning.
A/C Condenser	The outside fan unit of the Air Conditioning system. It removes the heat from the freon gas and "turns" the gas back into a liquid and pumps the liquid back to the coil in the furnace.
A/C Disconnect	The main electrical ON-OFF switch near the A/C Condenser.
AAR	Abbreviation for American Association of Railroads. AAR is a subdivision of the Department of Transportation.
Abatement	The actions taken to reduce the amount, degree of the hazard, or intensity of the release or threatened release of a hazardous material.
ABC extinguisher	A fire extinguisher that can be used on fires involving ordinary combustibles, flammable liquids, and energized electrical equipment; may also be known as a multipurpose extinguisher.
Absolute pressure	Pressure measured with respect to zero pressure or a vacuum. It is equal to the sum of a pressure gauge reading and the atmospheric pressure at the measurement location.
Absolute temperature	Temperature based on an absolute scale expressed in either degrees Kelvin (K) or degrees Rankine (R), corresponding respectively to the centigrade (C) or (F) scales. Degrees Kelvin is obtained by adding 273 to the centigrade temperature, or subtracting the centigrade temperature, from 273 if below 0°C. Degrees Rankine are obtained by algebraically adding the Fahrenheit reading to 460. Zero degrees K is equal to -273°C, and 0 degrees R is equal to -459.69°F.
Absolute zero	The minimum point on the thermodynamic temperature scale, which is 0 degrees Kelvin, -273.16 degrees centigrade, 0 degrees Rankine, or -459.69° Fahrenheit. This is a hypothetical temperature at which there is a total absence of heat.
Absorb	The penetration of one substance into the body of another.
Absorbent	A solid material that takes in liquids or gaseous substances (like a sponge) and undergoes chemical and/or physical changes as a result. Penetration can be capillary, osmotic, solvent, or chemical. Some of the materials typically used, as absorbents are sawdust, clays, charcoal, and polyolefin type fibers.
Absorption	The process of an agent being taken in by a surface (clothing, fabrics, wood, etc.,) much like a sponge and water. A route of exposure. It occurs when a toxic material contacts the skin, and then enters the bloodstream by passing through the skin.
AC	Alternating current.
Academy	A training school; a place to train, learn, study, and achieve
Accelerant	An agent used to initiate or speed the spreading of fire. The most common accelerants are flammable or combustible liquids.
Accelerator	A device attached to a dry-pipe sprinkler system for rapid removal of air in the system; a device to control the speed of a vehicle by regulating the fuel supply.
Acceptable entry conditions	Conditions that must exist in a confined space before entry is permitted to ensure that personnel can safely enter and carry out the work.
Acceptable risk	A risk, judged to be outweighed by corresponding benefits, or one that is of such a degree that it is considered to pose minimal potential for adverse effects.
Access corridor	A designated geographic area through which entrance into the "hot" or exclusion mitigation personnel permit zone. Typically, the access corridor serves as, or is near, the decontamination corridor and borders the hot and warm zones.
Accident	An unexpected and uncontrolled event generally resulting in injury, loss of property or disruption of services. A chance occurrence arising from unknown causes; an unexpected happening due to carelessness, ignorance, and the like. Any unplanned event that interrupts or interferes with the orderly progress of a production activity or process.
Accident prevention	Efforts or counter measures that are taken to reduce the number and severity of accidents.
Accordion fold	A fold for salvage covers.
Accordion load	A system of loading hose in the hose bed of a fire truck.
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Acetyl cholinesterase	An enzyme (a protein produced in the cells) which stops (inactivates) the action of acetylcholine by separating the acetylcholine into its components of acetic and chorine. This occurs as soon as acetylcholine has produced a muscle contraction. Nerve agents combine with acetyl cholinesterase to prevent it from performing its inactivation of acetylcholine.
Acetylcholine	A chemical compound formed from an acid and an alcohol that causes muscles to contract (neurotransmitter). It is found in various organs and tissues of the body. It is rapidly broken down by an enzyme, cholinesterase.
Acid	A hydrogen-containing corrosive material that reacts with water to produce hydrogen ions; a proton donor. Any of a class of chemical compounds whose aqueous solutions turn litmus paper red (have a pH less than 7) or reacts with and dissolves certain metals or reacts with bases to form salts. A compound capable of transferring a hydrogen ion in solution. A molecule or ion that combines with another molecule or ion by forming a covalent bond with two electrons from the other species.
Acquifer	A saturated water bearing formation of permeable rock sand or gravel.
Action level	A qualitative limit of chemical, biological, or radiological agent at which actions are taken to prevent or reduce exposure or contact.
Action Plan	See Incident Action Plan
Active ingredient	The chemical that has pesticide action. Active ingredients are listed in order on a pesticide label as percentage by weight or as pounds per gallon of concentrate. See Inert Ingredients.
Actual breakthrough time	The average time elapsed between initial contact of the chemical with the outside surface of the fabric and the detection time.
Actuate	To set into operation, especially an installed fire protection system.
Acute effects	An adverse effect on a human or animal body, with symptoms developing rapidly. See Chronic Effects.
Acute exposure	A dose that is delivered to the body in a single event or in a short period of time. The adverse effects resulting from a single dose or exposure to a material. Ordinarily used to denote effects observed in experimental animals.
Acute poisoning	Poisoning by a single exposure to a toxic chemical.
Acute toxicity	Any harmful effect produced by a single short-term exposure that may result in severe biological harm or death.
Adapter	A device to make a connection when the threads do not match or when they are different sizes.
Adiabatic compression	A term used to describe the generation of heat when a liquid or gas is compressed. If a flammable mixture is compressed rapidly, heat produced by the compression may be sufficient to raise the temperature of the mixture to its ignition point.
Adsorbent	A material that attracts molecules of a liquid or gas to its surface without undergoing chemical or physical alteration.
Adsorption	The process of an agent sticking to or becoming chemically attached to a surface.
Advanced Life Support	Advanced life support (ALS) is medical care provided by paramedics trained to assess a patient's condition, administer drugs, defibrillate and provide advanced airway management prior to transportation to the hospital.
Advancing a line	A line in the fire service is a line of hose. Advancing a line, therefore, is moving a line of hose forward toward a given assigned area from point where the hose-carrying apparatus has stopped. Also called "stretching a line".
AED	An automated external defibrillator (AED) detects and treats cardiac arrest due to the cardiac arrhythmias, ventricular fibrillation (VF) and ventricular tachycardia (VT). Uncorrected, these arrhythmias rapidly lead to irreversible brain damage and death. Unlike regular defibrillators, an automated external defibrillator automatically determines if a shock is indicated, and automatically selects and delivers the appropriate energy level. Once the pads are attached to the patient, the machine diagnoses the heart rhythm and determines if a shock is needed to treat ventricular tachycardia or ventricular fibrillation. If the machine determines that a shock is necessary, it will charge in preparation to deliver the shock. When charged, the machine instructs the user to ensure no one is touching the patient and then to press a button to actually deliver the shock.
Aerial ladders	A mechanically-operated ladder on a turn table attached to a ladder truck chassis and manufactured in various lengths, generally from 65 feet to 100 feet.
Aerial platform apparatus	See elevating platform apparatus
Aerial Truck	Also known as a ladder truck or just plain truck. A hydraulically powered ladder, mounted on a vehicle that also carries several different length extension ladders, extrication gear, ventilation equipment, and lighting. May or may not have a bucket or platform on the end.
Aerosol	Micron-size liquid droplets or solid particles dispersed in air by pressurized gases. When liquid droplets reach micron dimensions, their behavior becomes similar to solid particles of the same size. A suspension or dispersion of small particles (solids or liquids) in a gaseous medium. The dispersion of very fine particles of a solid or liquid in a gas, fog, foam, or mist.
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AFFF (Aqueous Film Forming Foam)	An acronym for Aqueous Film Forming Foam. It is a highly efficient type of fire suppressant agent used to attack flammable liquid fuel fires. This concentrated liquid is mixed with water and dispersed using a proportioning nozzle. The foam forms spontaneously upon ejection from the nozzle. The AFFF coats the pool of hydrocarbon fuel with a layer of foam which acts like a thermal and evaporation barrier to inhibit and eventually extinguish combustion. The "film forming" characteristics refers to the fact that even after the foam has dissipated, the aqueous layer formed from the water and concentrate mixture can coat a liquid hydrocarbon surface
A-Frame	A structural system utilizing members which when fastened together resemble the letter A.
A-frame ladders	The type of ladders that are hinged in the middle and can be used as either A-frame stepladders or as baby extension ladders.
Agency	An agency is a division of government with a specific function, or a nongovernmental organization (e.g., private contractor, business, etc.) that offers a particular kind of assistance. In ICS, agencies are defined as jurisdictional (having statutory responsibility for incident mitigation) or assisting and/or cooperating (providing resources and/or assistance). (See Assisting Agency, Cooperating Agency, Jurisdictional Agency, and Multi-agency Incident.)
Agency Administrator or Executive	Chief executive officer (or designee) of the agency or jurisdiction that has responsibility for the incident
Agency Dispatch	The agency or jurisdictional facility from which resources are allocated to incidents.
Agency Representative	An individual assigned to an incident from an assisting or cooperating agency who has been delegated authority to make decisions on matters affecting that agency's participation in incident management activities following appropriate consultation with the leadership of that agency. Agency Representatives report to the Incident Liaison Officer.
Agent	Agent refers to extinguishing material used in the fire service.
Aggregate	A mixture of sand and stone and a major component of concrete.
Agricultural chemicals	Chemicals such as pesticides, herbicides, fungicides, insecticides and fertilizers used in agricultural applications to control pests and disease or control/promote growth.
Air bag	An inflatable bag, often made of synthetic rubber, used to lift or stabilize heavy objects. Also a large inflatable bag into which persons can leap to escape danger.
Air bottle	A thick walled steel, fiberglass wrapped aluminum cylinder or composite metal cylinder equipped with a control valve, pressure gauge, and nipple outlet for a high pressure hose connection. In the fire service these tanks contain compressed air or oxygen. Each bottle carries approximately 66 cubic feet of compressed air at a pressure of 4500 pounds per square inch. See SCBA
Air bourne contaminants	Solid, liquid or gaseous materials that are mixed in the air and spread with air movements. Chemical vapors will readily mix with moving air. In still air, heavier gases-such as chlorine and gasoline fumes- will settle, whereas lighter gases-such as natural gas or hydrogen-will rise. Aerosols consisting of micron-size solid particles and liquid droplets can also be suspended in moving air but will settle at low air velocities or larger sizes. Asbestos, lead paint dusts, some agricultural chemicals, silica, radioactive particles, viruses, fungal spores, pollen and bacteria are examples of other airborne contaminants of concern.
Air chamber	A chamber filled with air and that serves to eliminate the pulsations caused by the operation of piston or rotary-gear pumps; a pulsation eliminator.
Air distribution system	The means by which cooling and/or breathing air is delivered to and distributed in a protective suit.
Air duct	A pipe, usually made of sheet metal, that conducts air to rooms from a central source
Air foam	A term used to describe mechanical foam, as differentiated from chemical foam; the type of foam concentrate that is added to the water and agitated or aerated to produce the Class B agent.
Air inversion	A meteorological condition in the earth's atmosphere in which the temperature of the air some distance above the earth's surface is higher than the air temperature of the surface. Normally, air temperatures decrease progressively as altitude increases. Such a condition traps air and released gases and vapors near the earth's surface, thus impeding their dispersion.
Air lock	A situation that can develop in a centrifugal pump that has not been properly primed. The rapid revolution of the impeller may create an air lock, which prevents priming of the pump.
Air mask or air pack	Worn by firefighters, a type of self-contained breathing device that provides an air supply from tanks through a regulator. See breathing equipment or SCBA
Air Operations Branch Director	The person primarily responsible for preparing and implementing the air operations portion of the Incident Action Plan. Also responsible for providing logistical support to helicopters operating on the incident.
Air pocket	A condition that occurs when a portion of non-collapsible intake hose is elevated higher than the intake of the pump when drafting; a void created by a cave-in; a confined space where air is trapped in the top of a car that has sunk beneath the water.
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Air pressure sprinkler system	A sprinkler system in which air pressure is used to force water from a storage tank into the system.
Air purification respirator (APR)	A device worn to filter particulates and contaminants from the air. An APR should only be worn in atmospheres where the type, size, and quantity of the contaminants are known and sufficient oxygen is present. Respirator that removes a contaminant from the air being inhaled by the wearer by passing air through a filter or cartridge containing a solid sorbent, such as activated charcoal, before the air is inhaled.
Air reactive materials	Substances that will ignite at normal temperatures when exposed to air.
Air space	The area between insulation facing and interior of exterior wall coverings. Normally a 1" air gap.
Air spring	A flexible air-inflated chamber in which the air pressure is controlled and varied to support the load and absorb road shocks; formerly called air bag
Air supply unit	A machine to refill exhausted compressed
Air Tank	See Air Bottle.
Aircraft emergencies	Alert 1: In-bound aircraft with possible onboard dilemma. Emergency response forces maintain readiness at response station for further development.
Aircraft fire protection	A specialized branch of the fire service dealing with airports or aircraft.
Airline mask	A mask worn by firefighters, connected to an air supply outside a contaminated area.
Airway	A medical term referring to the passageway from the mouth/nose to the lungs of a patient. A metal or plastic framework designed to fit the curvature of the mouth and throat to prevent air passageways from closing.
Al	See Aluminum Alloy.
Alarm	Any signal indicating the need for emergency fire service response; also, the device that transmits the alarm.
Alarm Assignment	A designation, usually in advance of the event, of the units to respond to a given fire alarm or signal; the entire complement assigned to any given alarm. As "the entire first alarm assignment went to work." (Example: two engines, one ladder, one battalion chief - a typical structure fire assignment).
Alarm Circuit	An electrical circuit connecting two points in an alarm system; for example, from the signal device to the fire station, from the central alarm center to all fire stations, or from the sending device to the audible alarm devices.
Alcohol foam	Blankets fires in the same manner as conventional foam, but it are intended for use with liquids, which are soluble in water, such as alcohol and acetone. It must be applied more carefully than regular foam because the mechanical strength of the bubbles is less.
Alcove	A recessed space connected at the side of a larger room.
Aldehydes	A group of highly reactive organic compounds that contain the common group CHO (carbon-hydrogen-oxygen), such as formaldehyde.
Alkali	A hydroxide-containing corrosive material that is soluble in water, neutralizes acids and is irritating or destructive to tissue. An alkali is a chemical substance that has a pH above 7 (also called "base"). The higher the pH of an alkali, the stronger the chemical is (or more "caustic"). Alkalis are often called detergent builders and are the major active ingredient in most carwash detergents, especially powdered products. The level of alkalinity in a detergent solution is often considered the true measure of a detergent's strength.
Alkaline	Any compound having the qualities of a base. Simplified, a substance that readily ionizes in aqueous solution to yield hydroxyl (OH-) anions. Alkalis have a pH greater than 7 and turn litmus paper blue.
All hands	A working fire engaging all apparatus of first-alarm assignment; may be followed by multiple alarms.
All service masks	A canister-type filter mask resembling a gas mask canister. (No longer approved or recognized for firefighting.)
Allergen	A substance that can trigger an immune response, resulting in an allergic reaction; also known as antigen. Allergens include living agents-such as bacteria, fungi, amoebae, and algae-and nonliving biological products-house dust, animal dander, spores, and insect feces.
Allergic asthma	An allergic illness that can be triggered by a variety of biological agents and exacerbated by such factors as cigarette smoke, sulfur dioxide, and emotional stress. It causes bronchiospasm, edema of the bronchial mucosa, and accumulation of bronchial mucous. Symptoms include coughing, wheezing, shortness of breath, itching of the nose, and rhino rhea.
Allergic illness	An illness caused by an allergen, usually upon second exposure. Although often associated with biological substances, allergic diseases may also be triggered by certain chemicals. Airborne exposure to allergens may occur on the skin, the nose, airways, even the lung alveoli. Antigenic material less than 5 μm such as mold spores, can penetrate the pulmonary region. Larger bioaerosols, such as pollens, tend to affect the upper respiratory tract. Allergic illnesses include allergic rhinitis, allergic asthma, allergic bronchopulmonary aspergillosis, hypersensitivity pneumonitis, and humidifier fever.
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Allergy	An increased reactivity to an antigen as a result of previous exposure.
Alligatoring	Convex portions of a carbonized material, separated by cracks or crevasses that form on the surface of char. Commonly forming on materials such as wood, as the result of pyrolysis or burning. Also called Char Blistering.
Allocated Resources	Resources dispatched to an incident
All-Risk	Any incident or event, natural or human-caused, that warrants action to protect life, property, environment, public health and safety, and minimize disruption of governmental, social, and economic activities
Alpha rays	Made up of very large particles, which are the same as the nucleus of the helium atom.
Alteration	A change in, or addition to, an existing building.
Alternating Current (ac)	A flow of electricity which reaches maximum in one direction, decreases to zero, then reverses itself and reaches maximum in the opposite direction. The cycle is repeated continuously. The number of cycles per second is equal to the frequency.
Aluminum alloy	A physical blend of metals with aluminum as the major constituent. Aluminum is a common material used for containerizing materials for transport because of its lightweight property.
Aluminum alloy ladder	A ladder made of aluminum and other materials like magnesium to make the ladder lightweight but strong.
Amalgam	A mixture of different elements.
Ambient	Surrounding, especially pertaining to the local environment, as in ambient air and ambient temperature.
Ambient Temperature	The temperature of the atmosphere of surrounding environment. Typically defined by industry standards as 25° C
Ambulance	A special vehicle equipped to transport sick or injured people to medical facilities.
Ambulatory	A patient capable of walking; one who is not bedridden.
American National Standards	Serves as a clearinghouse for nationally coordinated Institute (ANSI) voluntary safety, engineering, and industrial standards developed by industrial firms, trade associations, technical societies, consumer organizations, and government agencies.
Ampere (A)	Unit of electrical current flow, or rate of flow of electrons. Ampere The unit used in the measure of the rate of flow of electricity.
Analysis	The chemical determination of the composition of a substance.
Anchor bolt	A threaded rod inserted in masonry construction for anchoring the sill plate to the foundation.
Anemometer	A device to sense and measure air velocity.
ANFO	An ammonium nitrate and fuel oil mixture, commonly used as a blasting agent. The manufacturer or user determines the proportions. It is commonly mixed with the addition of an "enhancer" such as magnesium or aluminum to increase the rate of burn.
Angergols	Mixtures of fuels and oxidizers that do not react or ignite when combined.
Angle iron	A structural piece of rolled steel shaped to form a 90-degree angle.
Angle of approach	Angle formed by level ground and a line from the point where the front tires of a vehicle touch the ground to the lowest projection at the front of the apparatus.
Angle of departure	Angle formed by level ground and a line from the point where the rear tires of a vehicle touch the ground to the lowest projection at the rear of the apparatus
Anhydrous	Free from water, dry. Being without water, especially water of crystallization.
ANSI (The American National Standards Institute)	A clearinghouse for nationally coordinated voluntary safety, engineering and industrial standards developed by industrial firms, trade associations, technical societies, consumer organizations and government agencies.
Antenna	A device that collects and focuses electromagnetic energy, i.e., contributes an energy gain. Term usually applied to communication devices or equipment to receive and transmit radio frequencies.
Anticholinergic	An agent or chemical that blocks or impedes the action of acetylcholine, such as the antidote atropine.
Anticholinesterase	A substance that blocks the action of cholinesterase (acetylcholinesterase) such as nerve agents.
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Antidote	A substance, which neutralizes toxic agents or their effects
Anti-electrocution platform	Slide-out platform mounted beneath the side running board or rear step of an apparatus equipped with an aerial device. This platform is designed to minimize the chance of the driver/ operator being electrocuted should the aerial device come in contact with energized electrical wires or equipment.
Apparatus	An engine-driven fire truck of any variety, or a group of fire trucks. The word is used for both singular and plural construction.
Apparatus Bay or Room	That area of the fire station in which apparatus is parked and stored.
Apparatus floor	The portion of a fire station on which fire trucks are parked.
Apparatus Operator	Engineer, driver, aerial ladder operator or anyone acting in any one of these positions. Can also be known as Fire Apparatus Operator or FAO
Appliance	This term refers to those objects that are used in connection with the hose lines but are not actually part of the hose themselves. This group contains, gated wyes, siamese, nozzles, deluge monitors and deck guns.
Applicator	A special pipe or nozzle attachment for applying an extinguishing agent.
Applicator pipe	Curved pipe attached to a nozzle for precisely applying water over a burning object.
Apprenticeship	Seldom used in municipal fire departments without a formal training academy. Apprenticeship training is not less than three years, supplemented by the required hours of related technical instruction. Apprentices are subject to probationary periods, the length of which is stipulated in local programs. The fire service apprenticeship-training program was developed by the International Association of Fire Fighters and approved by the United States Department of Labor, Federal Committee on Apprenticeship, February 18, 1972.
Approach suit	Personal protective equipment used with SCBA, which allows response personnel to operate in high temperature atmospheres for short periods of time. Direct flame impingement is not permitted when using this garment. This is NOT a close proximity suit.
Appurtenances	Mechanical devices connected to a container opening needed to make a container gas tight. These include pressure relief devices, shut-off, backflow, excess flow, internal valves, liquid level gauging devices, pressure relief devices, pressure gauges, and plugs.
Apron	Inside window trim placed under the stool and against the wall. Also, the front and or rear driveway to a apparatus truck room
Aqueous Film Forming Foam (AFFF)	Also know as "A Triple F". Synthetic foam concentrate that, when proportioned with air and water, is a highly effective extinguishing and blanketing agent on hydrocarbon fuels. Typically proportioned at 3% or 6% foam concentrate to water
Arc	Sparking that results when undesired current flows between two point of differing potential.
Arcade	A series of arches supported by a row of columns.
Arch	A curved structure that will support itself by mutual pressure and the weight above its curved opening.
Area Command (Unified Area Command)	An organization established (1) to oversee the management of multiple incidents that are each being handled by an ICS organization, or (2) to oversee the management of large or multiple incidents to which several Incident Management Teams have been assigned. Area Command has the responsibility to set overall strategy and priorities, allocate critical resources according to priorities, ensure that incidents are properly managed, and ensure that objectives are met and strategies followed. Area Command becomes Unified Area Command when incidents are multi-jurisdictional. Area Command may be established at an emergency operations center facility or at some location other than an incident command post.
Area of Origin	The room or area where a fire began. See also Point of Origin.
Area wells	Corrugated metal or concrete barrier walls installed around a basement window to hold back the earth
Areas wall	A wall surrounding an areaway.
Areaway	A recessed area below grade around the foundation to allow light and ventilation into a basement window or doorway.
Aromatic hydrocarbons	A large class of highly volatile hydrocarbons containing a benzene ring, including toluene, xylene, ethyl benzene, and styrene. Sources include paints, adhesives, and solvents.
Arrow Pattern	A fire pattern displayed on the cross section of a burned wooden structural member.
Arson	Arson is the willful and malicious burning of the property of another. This meaning has been broadened by statute in many jurisdictions to include one's own property. The crime of arson is usually classified in two or more degrees, the severity of which is determined by several factors - the type of property involved, value of property, whether or not the property is occupied, if the crime was committed at night or during the daytime, and if there was any danger to human life.
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Arson Task Force or Squad	A group of qualified and certified individuals, generally consisting of both police and fire officers, who are assigned to investigate fires of suspicious origin.
Arsonist	Any person who commits the crime of arson.
Articulating aerial platform	Aerial device that consists of two or more booms that are attached with hinges and operate in a folding/unfolding manner. A passenger-carrying platform is attached to the working end of the device.
Articulating boom	Arm portion of the articulating aerial platform.
Artificial Resuscitation	Breathing maintained by an artificial means. (Also called artificial respiration and artificial ventilation.)
Asbestos	A known carcinogen, asbestos is a group of small, jagged sub- micron mineral fibers. Common types of asbestos include chrysotile, crocidolite and anthophyllite. Inhaling substantial quantities of asbestos may cause asbestosis (a disease that blocks the lungs with thick, fibrous tissue); bronchogenic cancer (cancer of the bronchial tubes); or mesothelioma (a rare and fatal cancer of the lining of the chest or abdomen).
Aseptic	Sterile, free from viable microbiological contamination.
Ash pit	The area below the hearth of a fireplace which collects the ashes.
ASME	Abbreviation for the American Society of Mechanical Engineers. ASME makes recommendations on designs and materials to be used for handling hazardous materials.
Asphalt	A mineral insoluble in water and used extensively in building for waterproofing roof coverings and driving surfaces
Asphalt roofing	A flooring and waterproofing material composed of saturated asbestos or rag felt cemented together with asphalt or tar pitch.
Asphalt saturated felt	Used as an underlayment material in roofing.
Asphalt shingles	A type of composition shingles made of felt saturated with asphalt and surfaced with mineral granules.
Asphyxia	Lack of oxygen and interference with oxygenation of the blood. Can lead to unconsciousness.
Asphyxiant	A vapor or gas that can cause unconsciousness or death by suffocation (lack of oxygen). Most simple asphyxiants are harmful to the body when they become so concentrated that they reduce (displace) the available oxygen in air (normally about 21%) to dangerous levels (18% or lower). Chemical asphyxiants, like carbon monoxide (CO), reduce the blood's ability to carry oxygen or, like cyanide, interfere with the body's utilization of oxygen.
Asphyxiation	A condition that causes death because of a deficient amount of oxygen supplied to the brain and other vital organs. This could be due to a low atmospheric oxygen level due to displacement or an excessive amount of carbon monoxide and/or other gases in the blood. Asphyxiation is one of the principal potential hazards of working in confined spaces. Commonly known as suffocation.
Aspirator	A suction device for removing undesirable material from the throat of a victim.
Assessment	The process of determining the nature and degree of hazard. Primarily used for hazardous material or hazardous materials incident. However could be used in patient care for determining injury or illness. Can be used in disasters for the appropriate use of resources by doing a damage assessment. The act of estimating the merit of a mitigation procedure. This evaluation should weigh the risk verses the overall objective of the incident. A proper assessment will consider hazards or treatment modalities associated with each phase of operation.
Assigned Resources	Resources checked in and assigned work tasks on an incident
Assignments	Tasks given to resources to perform within a given operational period, based upon tactical objectives in the Incident Action Plan.
Assistant	In the NIMS context, it is a title for subordinates of the Command Staff positions. The title indicates a level of technical capability, qualifications, and responsibility subordinate to the primary positions. Assistants may also be assigned to unit leaders. Also this is a command staff title for fire officer designation. i.e. Assistant Chief. In this instance he is subordinate to the Deputy Chief.
Assisting Agency	An agency or organization providing personnel, services, or other resources to the agency with direct responsibility for incident management. See also Supporting Agency.
Asthma	A disease of the pulmonary or lower respiratory system characterized by episodic bronchial constrictions, which cause severe wheezing and shortness of breath.
ASTM	Abbreviation for the American Society for Testing and Materials. This organization devises consensus standards for materials characterization and use. ASTM is a not-for-profit organization that provides a forum for producers, users, ultimate consumers, and those having a general interest to meet on common ground and write standards for materials, products, systems, and services.
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Astragal	A molding, attached to one of a pair of swinging double doors, against which the other door strikes.
ATF (Bureau of Alcohol, Tobacco and Firearms)	A division of the U.S. Department of Treasury; regulates the storage, handling, and transportation of explosives (among other responsibilities). This organization has capabilities of investigation and enforcement of crimes committed using or involving these products.
Atmospheric ceiling	The level in the atmosphere at which a heated column ceases to rise and levels off.
Atmospheric displacement	A system or method of applying water fog in a superheated area, causing the water to be quickly converted into steam, which expands and displaces the atmosphere in a burning room or building.
Atmospheric pressure	Pressure exerted by the atmosphere; about 14.7 pounds per square inch (100 kPa) at sea level due to the weight of air . Atmospheric pressure increases as elevation is decreased towards and below sea level and decreases as elevation increases above sea level.
Atom	The smallest particle of an element that can exist.
Atomic number	The number of protons in an atom.
Atomic weight	Atomic weights relate to the weights of molecules and atoms. Basically, it equals the number of protons plus neutrons.
Atrium	An open court within a building.
Atropine	A medication used as an antidote for nerve agents and certain organic phosphate poisoning. An anticholinergic used as an antidote for nerve agents to counteract excessive amounts of acetylcholine. It also has other medical uses.
Attack	Any action to control fire. The actual physical firefighting operation using equipment and manpower implementing tactical plans on the fireground in an aggressive manner.
Attack hose	Hose between the attack pumper and the nozzle(s); also, any hose used in a handline to control and extinguish fire. Minimum size is 1 1/2 inch.
Attack lines	Hose lines or fire streams used to attack, contain, or prevent the spread of a fire.
Attack pumper	Pumper that is positioned at the fire scene and is directly supplying attack lines.
Attic	The space between the roof and the ceiling.
Attic access	An opening that is placed in the drywalled ceiling of a home providing access to the attic.
Attic Ladder	A ladder usually 8-10 feet long that usually can be folded so that the two beams touch each other. Also called a scuttle hull or pencil ladder in some parts of the country. Comes in lengths of 6 to 12 feet.
Attic Ventilators	In houses, screened openings provided to ventilate an attic space.
Audible alarm	An alarm actuated by heat/smoke, flame-sensing devices or the water flow in a sprinkler system.
Auditorium raise	A system of extending a ladder perpendicular and holding it in place from four opposite points of the compass by four guy ropes attached to the top of the ladder. (Also called church raise or steeple raise.)
Auscultation	Diagnostic monitoring done by listening to the sounds made by internal organs or any internal body part.
Authority having jurisdiction	The organization, office, or individual responsible for equipment, an installation, procedure or approving and enforcing codes.
Authorized entrant (Confined Space)	An employee who is authorized by the employer or the designee of the employer to enter a confined space. Outside emergency service organizations, this may require a permit before any person enters a confined space.
Autoignition	Initiation of combustion by heat but without a spark or flame.
Auto-ignition temperature	The same as ignition temperature except that no external ignition source is required for ignition since the material itself has been heated to ignition temperature; the spontaneous ignition of the gases or vapor given off by a heated material. See ignition temperature.
Automatic alarm	An alarm actuated by heat, smoke, flame-sensing devices, or the water flow in a sprinkler system conveyed to local alarm bells and/or the fire station. Also applies to alarm boxes that automatically transmit a coded signal to the fire station to give the location of the alarm box.
Automatic nozzle	Fog stream nozzle that automatically corrects itself to provide a good stream at the proper nozzle pressure.
Automatic Sprinkler	An appliance for fire control and extinguishment by which water is piped to specifically designed orifices or sprinkler "heads" distributed throughout a property and operated automatically in the event of fire. Typically during a fire, the sprinkler heads above the involved area activate one at a time; the entire system does not go off at once. However there are specific applications designed to do so.
Automatic sprinkler sets	An automatic sprinkler kit contains the tools and equipment required to close and service an open sprinkler head.
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Automatic sprinkler system	A fire protection device consisting of a series of intricately combined pipes and valves arranged to automatically distribute sufficient quantities of water to either extinguish a fire or to hold it in check until firefighters arrive. A system includes all the necessary elements to trigger the mechanism, notify the occupants that it is in use and to call for the fire department to respond. Additionally the system includes valves to turn it on and off.
Autonomic nervous system	Nervous system in vertebrates which regulates the vital internal organs in an involuntary manner.
Auxiliary	Additional fire fighting equipment or staffing that are not part of the regular complement assigned to the fire service. Ladies (spouse) group organized to assist the fire department.
Available Resources	Resources assigned to an incident, checked in, and available for a mission assignment, normally located in a Staging Area.
Average precipitation	The average amount of precipitation (rain or snow) that occurs over a specified period.
Axe, fire	A fire axe has a pick or fiat head and a blade on the opposite end.
Azimuth	A compass bearing expressed in degrees of rotation clockwise from true north.