Emergency Response Safety and Health Database: Glossary

Glossary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

A

Terms	Description
Acetylcholine	A substance that transmits nerve impulses (neurotransmitter).
Acetylcholinesterase	An enzyme that occurs especially in some nerve endings and in the blood and promotes the breakdown of acetylcholine. Nerve agents inhibit the action of this enzyme.
Acid	Any of various typically water-soluble and sour compounds that in solution are capable of reacting with a base to form a salt, that redden litmus, that have a pH less than 7, and that are hydrogen-containing molecules or ions able to give up a proton to a base or are substances able to accept an unshared pair of electrons from a base.
Acidosis	An abnormal increase in the acidity of the body’s fluids, caused either by accumulation of acids or by depletion of bicarbonates.
Acrid	Unpleasantly sharp, pungent, or bitter to the taste or smell.
Acuity	Acuteness of vision or perception.
Acute	Having a sudden onset, sharp rise, and short course.
Acute Exposure Guideline Level (AEGL)	Guideline intended to describe the risk to humans resulting from once-in-a-lifetime, or rare, exposure to airborne chemicals. Acute exposures are defined as single, non-repetitive exposures for not more than 8 hours. There are three AEGL values: AEGL-1: Discomfort, non-disabling. AEGL-2: Irreversible or other serious, long-lasting effects or impaired ability to escape. AEGL-3: Life-threatening effects or death.
Aerosol	A suspension of fine solid or liquid particles in gas.
Afebrile	Free from fever.
Agent	A factor such as a microorganism, chemical substance, or form of radiation that can result in illness or injury.
Agonist	A chemical substance (such as a drug) that is capable of combining with a receptor on a cell and initiating the same reaction or activity typically produced by the binding of a substance that normally occurs in the body (i.e., is endogenous).
Air-purifying respirator (APR)	An air-filtering device that covers the nose and mouth and removes contaminants from the surrounding air by passing it through a filter, cartridge, or canister. A variety of filter cartridges are designed to capture specific particles and/or gases. Filters must be replaced once absorption capacity is depleted.
Alopecia	Loss of hair; baldness.
Ambient	Surrounding or encompassing, e.g., the ambient environment.
Ampule	A small glass vial that is sealed after filling; often used as a container for a solution to be given by hypodermic injection.
Analgesic	A drug that alleviates pain without causing loss of consciousness; a pain-reliever.
Anemia	An abnormal deficiency in the oxygen-carrying component of the blood, measured in unit volume concentrations of hemoglobin, red blood cell volume, or red blood cell number.
Anesthetic	An agent that causes loss of sensation with or without the loss of consciousness.
Anion	A negatively charged ion, especially the ion that migrates to an anode in electrolysis.
Anoxia	Deficiency of oxygen, especially one so severe as to result in permanent damage.
Antagonist	A chemical that acts within the body to reduce the physiological activity of another chemical substance (as an opiate), especially one that opposes the action on the nervous system of a drug or a substance occurring naturally in the body by combining with and blocking its nervous receptor.
Antibody	Any of a large number of proteins that are produced normally by specialized cells after stimulation by an antigen (e.g., a bacterium, virus, parasite, etc.) and act specifically against the antigen in an immune response. Also called immunoglobulin.
Antiemetic	A drug that prevents or alleviates nausea and vomiting.
Antimitotic agent	An agent that prevents or interferes with cell division (mitosis).
Anxiolytic	An anti-anxiety drug.
Aplasia	Incomplete or faulty development of an organ or tissue.
Apnea	Temporary absence or cessation of breathing.
APR	See definition for Air-purifying respirator
Aqueous solubility	The amount of a substance (solute) that can be dissolved in a given amount of water(solvent). Aqueous solubility is based on the chemical’s respective Log Kow values: Log Kow = 1, soluble Log Kow 1-5, slightly soluble Log Kow > 5, insoluble
Arsenic	A highly poisonous metallic element existing in three forms, yellow, black, and gray, of which the brittle, crystalline gray is the most common. Arsenic and its compounds are used in insecticides, weed killers, solid-state doping agents, and various alloys.
Arthralgia	Pain in a joint or joints.
Ascending peripheral neuropathy	Numbness that begins in the limbs.
Ascorbic acid	Vitamin C.
Asphyxiant	A substance capable of inducing asphyxia, which is a lack of oxygen or an excess of carbon dioxide in the body, usually caused by the interruption of breathing and resulting in unconsciousness.
Asthma	A chronic respiratory disease, often arising from allergies, that is characterized by sudden recurring attacks of labored breathing, chest constriction, and coughing.
Asymptomatic	Exhibiting no symptoms of disease.
Ataxia	Inability to coordinate muscular movement.
Atelectasis	Total or partial collapse of the lung.
Atrophy	A wasting or decrease in size of a body organ, tissue, or part owing to disease, injury, or lack of use.

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B

B

Terms	Description
BAL	British Anti-Lewisite, an antidote for Lewisite exposure.
Barbiturate	Any of a class of drug used especially as sedatives, hypnotics, and antispasmodics.
Benzodiazepine	Any of a class of drug used as antianxiety agents, muscle relaxants, sedatives, hypnotics, and sometimes as anticonvulsants.
Beta particle	A subatomic particle that is ejected from the nucleus of unstable atoms. Beta particles can travel through several layers of human skin, and exposure to large sources of beta radiation can cause burns or skin reddening. Beta particles that enter the body can damage cells, which can lead to cell death or, later in life, to cancer.
Beta radiation	See definition of Beta particle.
Beta-adrenergic	Pertaining to a certain type of receptor, the beta-receptor, postulated to exist on the surface of certain cells and reacting to adrenaline or adrenaline-like agents.
Biological agent	A living organism that can cause disease, sickness, and mortality in humans.
Biotoxin	A substance produced by a living organism, such as a plant or fish, that has toxic effects.
Blanching	Whitening of the skin.
Blepharospasm	Spasmodic blinking.
Blister agent (vesicant)	A substance that causes blistering of the skin and mucous membranes. Exposure is through liquid or vapor contact with any tissue (i.e., eyes, skin, lungs).
Bradycardia	Slow heart rate, usually fewer than 60 beats per minute in an adult human.
Bronchi	The large airways leading to the lungs. Singular = bronchus.
Bronchiole	One of the small airways leading to the lungs.
Bronchitis	Chronic or acute inflammation of the large airways.
Bronchoconstriction	Narrowing of the large airways.
Bronchodilation	Expansion of the large airways.
Bronchodilator	A drug which enlarges the large airways.
Bronchopneumonia	Inflammation of small areas of the lung.
Bronchospasm	Spasmodic narrowing of the large airways.
Bulla	A large blister or vesicle. Plural = bullae.

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C

C

Terms	Description
Cachexia	Physical wasting and malnutrition.
Camphor	An aromatic crystalline compound, obtained naturally from the wood or leaves of the camphor tree or synthesized and used as an insect repellent, in the manufacture of film, plastics, lacquers, and explosives, and in medicine chiefly in external preparations to relieve mild pain and itching.
Capillaries	The smallest blood vessels.
Carcinogenic	Causing or producing cancer.
Carcinogenicity	Cancer-causing potential (of an agent or substance).
Cardiac arrest	Temporary or permanent cessation of the heartbeat.
Cardiac arrhythmia	Alteration of the heart rhythm
Cardiac dysrhythmia	An abnormality in an otherwise normal rhythmic pattern of the heart.
Cardiac sensitization	Increased responsiveness or susceptibility of the heart to stimulating hormones following exposure to a chemical, which can lead to irregular heart rhythms (arrhythmias), cardiac arrest, or death.
Cardiopulmonary	Of, relating to, or involving both the heart and the lungs.
Cardiopulmonary failure	Heart and respiratory failure.
Cardioversion	Application of an electric shock to restore normal heartbeat.
Cast	A mass formed in cavities of diseased organs.
Cathartic	An agent for purging the bowels, especially a laxative.
Caustic	Capable of burning, corroding, and dissolving, or eating away by chemical action.
CBRN	Chemical, Biological, Radiological, Nuclear
Central nervous system (CNS)	The brain and spinal cord.
Cerebral edema	Accumulation of fluid in and resultant swelling of the brain.
Chelating agent	An agent that removes a heavy metal, such as lead or mercury, from the bloodstream.
Chemical agent	A chemical substance that is intended for use in military operations to kill, seriously injure, or incapacitate people through its physiological effects.
Chemical protective clothing and equipment	Any item of clothing (e.g., gloves, boots, suits) used to isolate parts of the body from direct contact with potentially hazardous substances. Safe use of this type of protective clothing and equipment requires specific skills developed through training and experience. This type of special clothing may protect against one chemical, yet be readily permeated by chemicals for which it was not designed. Therefore, protective clothing should not be used unless it is compatible with the released material. This type of special clothing offers little or no protection against heat and/or cold.
Chemosis	Swelling of the outer membranes of the eye.
Chemotherapeutic agent	A chemical agent or drug used in the treatment of disease; chemotherapeutic agents are selectively toxic to the causative agent of the disease, such as a virus, bacterium, or other microorganism.
Cholinesterase	An enzyme found primarily at nerve endings that catalyzes the breakdown of acetylcholine.
Chorea	Any of various nervous disorders of infectious or organic origin marked by spasmodic movements of the limbs and facial muscles and by incoordination.
Choreiform	Spasmodic and uncoordinated. See also chorea.
Chronic	Marked by long duration, by frequent recurrence over a long time, and often by slow progression to become more serious.
Clonic	Intermittent (e.g., movements).
CNS	Central nervous system.
CNS depression	Reduced level of consciousness.
CNS excitation	Increased level of consciousness.
Coagulopathy	A disease or condition affecting the ability of the blood to clot (coagulate).
Coma	State of profound unconsciousness.
Combustible	Will ignite, burn, or support combustion.
Combustible liquid	A liquid that has a flash point greater than 60.5°C (141°F) and below 93°C (200°F). U.S. regulations permit a flammable liquid with a flash point between 38°C (100°F) and 60.5°C (141°F) to be re-classed as a combustible liquid.
Concussion	An injury to an organ, especially the brain, produced by a violent blow and followed by a temporary or prolonged loss of function.
Conjuctival injection	Accumulation of blood in the membranes of the eye (see also “injected conjuctiva”).
Conjunctiva	The mucous membrane that lines the inner surface of the eyelid and the exposed surface of the eyeball. Plural = conjunctivae.
Conjunctivitis	Inflammation of the membranes of the eye (conjuctiva).
Contact dermatitis	Inflammation of the skin caused by direct contact with an irritant.
Convulsion	An intense, paroxysmal, involuntary muscular contraction. During convulsions, the patient’s body shakes rapidly and uncontrollably and his/her muscles contract and relax repeatedly. The term “convulsion” is often used interchangeably with “seizure,” although there are many types of seizure, some of which have subtle or mild symptoms instead of convulsions.
Copious	Large in quantity; abundant.
Cornea	The transparent part of the coat of the eyeball that covers the iris and pupil and admits light to the interior.
Corneal epithelium	The outer layer of the cornea (of the eye).
Corticosteroid	Any of the steroid hormones produced by the adrenal cortex or their synthetic equivalents, such as cortisol and aldosterone.
Cranial nerve palsy	A form of paralysis.
Crystalline	Being, relating to, or composed of crystals.
Cyanosis	Bluish discoloration of the skin due to deficient oxygenation of the blood.
Cylindruria	Presence of casts (masses) in the urine.
Cytotoxic	Having a harmful effect on cells; cell-killing or cell-harming.

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D

D

Terms	Description
Decontamination	The removal of a dangerous material from any person, object, or area to the extent necessary to prevent potential adverse health effects.
Decontamination	The destruction, physical removal, or reduction of a toxic substance to an acceptable level.
Decubitus ulcers	Bed sores.
Defecation	The discharge of feces.
Deliquescent	Tending to dissolve and become liquid by the absorption of moisture from the air.
Dementia	Marked decline in mental function.
Depersonalization	A feeling of loss of identity.
Derealization	A feeling of altered reality.
Dermal	Of or relating to the skin (dermis).
Dermatitis	Inflammation of the skin.
Dermatosis	A skin disease, especially one that is not accompanied by inflammation. (Plural = dermatoses.)
Detoxification	The metabolic process by which the toxic qualities of a poison or toxin are reduced by the body.
Detoxify	To treat (an individual), usually under a medically supervised program designed to rid the body of toxic substances.
Deviations (conjugate or dissociated)	Abnormal movements of one or both eyes.
Diaphoresis	Sweating, especially when profuse and medically induced.
Diatomaceous	Consisting of diatoms or their skeletons; diatomaceous earth is a light, crumbly silica-containing material used in filtration.
Dike	A barrier blocking a passage, especially for protection.
Diplopia	Double vision.
Disseminated intravascular coagulation	Widespread formation of clots in the blood vessels.
Diuretic	Tending to increase the discharge of urine.
DNA	A nucleic acid that carries the genetic information in the cell and is capable of self-replication and synthesis of RNA.
Don	To put on (clothing).
Dysarthria	Difficulty in articulating words, resulting in slurred speech.
Dysphagia	Difficulty in swallowing.
Dysphasia	Difficulty in using or understanding language.
Dysphonia	Defective use of the voice; slurred speech.
Dyspnea	Difficulty in breathing, or shortness of breath.
Dysrhythmia	Abnormal or disordered heart rhythm.

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E

E

Terms	Description
ECG	See “electrocardiogram”
Ectropion	Abnormal turning out of the eyelid.
Eczematoid	Resembling eczema, an inflammatory condition of the skin characterized by redness, itching, and oozing blister-like lesions, which become scaly, crusted, or hardened.
Edema	An abnormal, excessive accumulation of thin, watery fluid in tissue spaces or a body cavity.
Effluent	Something that flows out, especially a discharge of waste into the environment.
Electrocardiogram (ECG)	A recording of the electrical activity of the heart.
Electrolyte	Any of the ions (as of sodium, potassium, calcium, or bicarbonate) that in a biological fluid regulate or affect most metabolic processes (as the flow of nutrients into and waste products out of cells).
Emesis	The act of vomiting.
Emphysema	A disease of the lungs characterized by air-filled expansions in lung tissues.
Encephalopathy	A disease of the brain.
Endophthalmitis	Inflammation of the interior of the eyeball.
Endoscopic	A medical procedure that uses an instrument (endoscope) to examine visually the interior of a bodily canal or a hollow organ such as the colon, bladder, or stomach.
Endotracheal	Within or passing through the trachea (windpipe), e.g., an endotracheal tube.
Endotracheal intubation	Insertion of a tube within the trachea.
Enteritis	Inflammation of the intestinal tract, especially of the small intestine.
Epigastric	Abdominal, specifically, over or above the stomach.
Epistaxis	Nosebleed.
Epithelium	The covering of internal and external surfaces of the body, including the lining of vessels and other small cavities.
ERPG	Emergency Response Planning Guidelines developed by the American Industrial Hygiene Association (AIHA).
ERPG-1	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.
ERPG-2	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.
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.
Erythema	Redness of the skin.
Erythrocyte	Red blood cell.
Ethanol	A colorless, volatile, flammable liquid that is the intoxicating agent in liquors and is also used as a solvent.
Euphoria	A disproportionate feeling of well-being.
Evolve	To give off or emit (e.g., a gas).
Exothermic	Releasing heat.

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F

F

Terms	Description
Face shield	A supplementary protective device worn to shield the wearer’s face from certain hazards. Face shields are secondary protectors only and must be worn with safety glasses or goggles.
Fasciculation	Muscular twitching.
Fatal	Causing death.
Febrile	Showing symptoms indicating fever; feverish.
Fibrosis	An increase in fibrous tissue situated within but not restricted to or characteristic of a particular organ or tissue.
Flaccid	Lacking firmness, resilience, or muscle tone.
Flaccid paralysis	Paralysis with reduced muscle tone and reflexes.
Flammable	Capable of being ignited and rapidly consumed by fire.
Flammable liquid	A liquid that has a flash point of 60.5°C (141°F) or lower.
Flash point	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.
Fog	See Water spray.
Fomepizole	A drug that is a competitive inhibitor of an enzyme (alcohol dehydrogenase) that catalyzes the breakdown of methanol and ethylene glycol into their toxic metabolites, and is used to treat poisoning by those substances.
Friction	Rubbing of one body against another.

G

G

Terms	Description
Gamma radiation	A packet of energy, called a photon, that is emitted from the nucleus of an unstable atom. Gamma radiation is high-energy electromagnetic radiation that can penetrate most substances (lead is the best barrier against gamma radiation). Because of its high energy, gamma radiation can penetrate the human body from the outside and damage cells, which could lead to cancer later in life.
Gas mask	A face covering device used to protect the wearer from injurious gases and other noxious materials by filtering and purifying inhaled air. It usually consists of a face cover with two eyepieces and a mouthpiece that contacts a canister containing a filter; the filter absorbs noxious gases as they pass through the canister to the mouth. The face cover also has a one-way outlet valve for exhaled air.
Gastric	Pertaining to the stomach.
Gastric hypomotility	Slowing of muscular movement of the stomach.
Gastric lavage	A procedure to empty the contents of the stomach, usually for analysis or removal of irritating elements such as poisons. Also called stomach pumping or gastric suction.
Gastritis	Inflammation of the lining of the stomach.
Gastroenteritis	Inflammation of the lining of the stomach and intestines.
Gastrointestinal (GI)	Relating to or affecting both the stomach and the intestines.
General population limit (GPL)	An airborne exposure limit designed to protect the general public.
Germinal	Of, relating to, or having the nature of a germ cell (sperm, egg, or their precursors).
GI	Gastrointestinal.
Glottis	The vocal apparatus of the larynx, consisting of the vocal cords and the opening between them.
Goggles	A wraparound, protective device that fits the face, surrounding the eyes in order to shield them from impact, splash and vapor hazards. Goggles are available non-vented or with direct or indirect vents.
Gonad	An organ in an animal that produce gametes, e.g., a testis or ovary.
Gout	A metabolic disease marked by a painful inflammation of the joints, deposits of uric acid salts in and around the joints, and usually an excessive amount of uric acid in the blood.
GPL	See: General population limit.
Green Zone	An area where contamination with chemical, biological, radiological, or nuclear (CBRN) agents is unlikely. This zone covers the area beyond the expected significant dispersal range of the initial event and secondary contamination range caused by traffic and emergency responders.

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H

H

Terms	Description
Half-life	The time required for half of the atoms of a radioactive substance to decay or disintegrate.
Halon	Any of several halocarbons used as fire-extinguishing agents.
Hematemesis	Vomiting blood.
Hematologic	Of or relating to the blood.
Hematopoietic	Relating to the formation of blood or blood cells in the body.
Hematuria	The presence of blood in the urine.
Hemodialysis	A medical procedure to remove wastes or toxins from the blood and adjust fluid and electrolyte imbalances.
Hemoglobinuria	The presence of hemoglobin (the oxygen-carrying pigment in the blood) in the urine.
Hemolysis	Lysis (destruction) of red blood cells (see also “intravascular hemolysis”).
Hemolytic anemia	Anemia caused by the destruction of blood cells.
Hemoptysis	Spitting up of blood.
Hemorrhage	Excessive bleeding.
Hemorrhagic	Pertaining to a hemorrhage.
Hemorrhagic gastritis	Inflammation of the lining of the stomach with bleeding.
Hemorrhagic gastroenteritis	Inflammation of the lining of the stomach and intestines with severe bleeding.
HEPA	High Efficiency Particulate Air filters
HEPA PAPR	High Efficiency Particulate Air Powered Air-Purifying Respirator
Hepatic encephalopathy	Central nervous system disease, which is a result of liver failure.
Hepatomegaly	Abnormal enlargement of the liver.
High Efficiency Particulate Air (HEPA) filters	Used in ventilation systems, HEPA filters remove 99.7% of particles 0.3 microns and smaller, which include dust, mold spores, dust mites, pet dander, allergens, and many biological agents such as anthrax spores. They do not purify the air for most chemical agents.
Hydrolysis	Decomposition of a chemical compound by reaction with water, such as the dissociation of a dissolved salt or the catalytic conversion of starch to glucose.
Hydrolyze	To subject to or undergo hydrolysis.
Hygroscopic	Readily taking up and retaining water or moisture.
Hyperemia	Abnormal accumulation of blood.
Hyperkalemia	High blood levels of potassium.
Hyperkeratosis	Thickening of the outer layer of the skin.
Hyperpigmentation	Darkening of a body part or tissue.
Hyperpnea	Increase in the rate and depth of breathing.
Hyperreflexia	Overactive body reflexes.
Hypertension	Abnormally elevated blood pressure.
Hyperthermia	Exceptionally high body temperature.
Hyperventilation	Excessive rate and depth of respiration.
Hypocalcemia	Low blood levels of calcium.
Hypoglycemia	Low blood levels of sugar (glucose).
Hypokalemia	Low blood levels of potassium.
Hypomagnesemia	Low blood levels of magnesium
Hyporeflexia	Underactive body reflexes.
Hypotension	Abnormally low blood pressure.
Hypothermia	Abnormally low body temperature.
Hypovolemia	A decrease in the volume of circulating blood.
Hypovolemic shock	A life-threatening condition in which the heart is unable to supply enough blood to the body because of inadequate blood volume or blood loss. May occur subsequent to serious dehydration.
Hypoxemia	Oxygen deficiency in the blood.
Hypoxia	Decreased oxygen supply to the tissues.

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I

I

Terms	Description
IDLH	See: Immediately dangerous to life and health.
Ileus	Obstruction of the intestines.
IM	Intramuscularly.
Immediately Dangerous to Life or Health	As defined by NIOSH, an immediately dangerous to life or health condition is a situation “that poses a threat of exposure to airborne contaminants when that exposure is likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from such an environment.” NIOSH also states that the purpose of establishing an IDLH is to “ensure that the worker can escape from a given contaminated environment in the event of failure of the respiratory protection equipment.”
Immiscible	Not mixing readily with water.
Incapacitating agent	An agent that produces temporary physiological and/or mental effects via action on the central nervous system. Effects may persist for hours or days, but victims usually do not require medical treatment, although treatment may speed recovery.
Inebriation	Drunkenness (intoxication).
Inert	Not readily reactive with other elements; forming few or no chemical compounds.
Inflammation	A local response to cellular injury that is marked by redness, heat, pain, swelling, cellular and blood vessel changes, and often loss of function and that serves as a mechanism initiating the elimination of noxious agents and of damaged tissue.
Inflammatory	Accompanied with, or tending to cause, inflammation.
Inhalation	The act of drawing in breath.
Inhibitor	An agent that slows or interferes with a chemical reaction; a substance that reduces the activity of another substance (as an enzyme).
Initial isolation and protective action distances	Two types of recommended safe distances listed in the U.S. Department of Transportation ERG 2000 for toxic inhalation hazard (TIH) substances, which are poisonous by inhalation and/or water-reactive materials, which produce toxic gases upon contact with water. The “Initial Isolation Distance” is a distance within which all persons should be considered for evacuation in all directions from the actual spill/leak source. The “Protective Action Distance” represents a downwind distance from the spill/leak source within which Protective Actions, those steps taken to preserve the health and safety of emergency responders and the public, could be implemented.
Injected conjuctiva	Accumulation of blood in the membranes of the eye (see also “conjuctival injection”).
Inspiratory	Of, relating to, or used for the drawing air into the lungs.
Intracranial	Occurring or situated within the skull (cranium).
Intracranial hypertension	Elevated pressure of the fluid surrounding the brain and spinal cord (cerebrospinal fluid, or CSF).
Intravascular	Within blood vessels or a blood vessel.
Intravascular hemolysis	Lysis (destruction) or red blood cells (see also “hemolysis”).
Intubation	Insertion of a tube into a hollow organ or body passage; to intubate.
Ion	An atom or a group of atoms that has acquired a net electric charge by gaining or losing one or more electrons.
Ipecac	A medicinal preparation made from the dried roots and rhizomes of a shrub, sometimes used to induce vomiting, particularly in cases of poisoning and drug overdose.
Iritis	Inflammation of the iris of the eye.
Irrigation	Continuous washing.
IV	Intravenously.

J

J

Terms	Description
Jaundice	Yellowish pigmentation of the skin and tissues.

K

K

Terms	Description
Keratitis	Corrosion of the cornea of the eye.

L

L

Terms	Description
Lability	The state of constantly undergoing or likely to undergo change; unstable.
Lacrimation	Excessive tear production.
Lacrimator	A tear-producing chemical.
Laryngeal	Relating to, affecting, or near the larynx (voice box).
Laryngitis	Inflammation of the voice box.
Laryngospasm	Involuntary contraction of the vocal cords that impedes airflow to the lungs.
Latent	Existing in hidden or dormant form; not currently showing signs of activity or existence.
Latent period	Symptom-free period.
Lavage	Washing out a hollow organ (such as the stomach) by flushing with water.
Lesion	An abnormal change in structure of an organ or part due to injury or disease, especially such a change that is circumscribed and well-defined.
Lethal	Capable of causing death
Lethargy	Abnormal drowsiness (see also somnolence).
Leukocyte	White blood cell.
Leukocytosis	Abnormal increase in the number of circulating white blood cells.
Leukopenia	A reduced white blood cell count.
Lipids	Substances, such as fats, that are some of the principal structural constituents of the cells of living organisms.
Lobular emphysema	Small areas of lung disease (see also “emphysema”)
Localized	Restricted to a definite part of the body; not general or systemic.
Lorazepam	A drug used therapeutically to control seizures.
Luminescent	Glowing.
Lung damaging agent	A substance that causes physical injury to the respiratory tract, including the lungs. In extreme cases, membranes swell and lungs become filled with fluid; death results from lack of oxygen.
Lymphocytosis	Abnormal increase in the number of lymphocytes (a kind of white blood cell).

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M

M

Terms	Description
Malaise	Vague feeling of generalized weakness.
Mandible	The lower jaw.
Mechanical ventilation	Artificial ventilation of the lungs (as by positive end-expiratory pressure) using means external to the body.
Mees’ lines	White lines in the nails.
Melanosis	Abnormal darkening of the skin or tissues.
Melena	The passage of bloody stools.
Metabolic acidosis	Accumulation of acid in the blood and tissues.
Metabolism	The process by which a substance is broken down in the body.
Metaplasia	Abnormal replacement of cells.
Methemoglobinemia	Excessive accumulation of an inactive form of hemoglobin in the blood.
Mg	Milligram.
Micturition	Urination.
Miosis	Contracted or pinpoint pupils.
Miscible	Capable of mixing readily, usually with water.
Mitosis	The process of cell division.
Motor dysfunction	Difficulty moving.
Mucosa	The lining of certain body passages, such as the gastrointestinal tract or the airways (see also “mucous membrane”).
Mucous membrane	A membrane rich in mucous glands; specifically, a membrane lining body passages and cavities that communicate directly or indirectly with the exterior, which functions in protection, support, nutrient absorption, and secretion of mucus, enzymes, and salts; the membrane is always soft and smooth and kept lubricated by the secretions of the cells and numerous glands embedded in the membrane. Also called mucosa.
Mucus	A gummy, slippery secretion produced by mucous membranes, which it moistens and protects.
Myalgia	Muscle pain.
Mydriasis	Dilated pupils.
Myelosuppression	Suppression of the bone marrow’s production of blood cells and platelets.
Myocardial	Pertaining to the muscular tissue of the heart.
Myocardial depression	A decrease in the heart’s ability to pump blood.
Myocardial failure	Heart failure.
Myocardium	The muscular tissue of the heart.
Myoclonic	A sudden, involuntary twitching of muscles or parts of muscles, without any rhythm or pattern, occurring in various disorders of the nervous system.

N

N

Terms	Description
n.o.s.	Not otherwise specified, e.g., where the name of a specific chemical is not listed in the applicable regulations, a generic name such as “Corrosive liquid, n.o.s.”is used on shipping papers.
Narcotic	A drug (as opium) that in moderate doses dulls the senses, relieves pain, and induces profound sleep, but in excessive doses causes stupor, coma, or convulsions.
Necrosis	Death of living tissue; specifically, death of a portion of tissue differentially affected by local injury (as through loss of blood supply, corrosion, burning, or the local lesion of a disease).
Necrotic	Affected with, characterized by, or producing necrosis.
Necrotizing bronchiolitis	Destruction of tissue and irritation of the airways.
Neoplasm	Abnormal growth of tissue, such as cancer.
Neoprene	A synthetic rubber produced by polymerization of chloroprene and used in weather-resistant products, adhesives, shoe soles, sportswear, paints, and rocket fuels.
Nerve agent	An agent that interferes with the function of the central nervous system. Exposure is primarily through contact with the liquid (via skin and eyes) and secondarily through inhalation of the vapor.
Nettle agent	An agent that causes severe irritation to the skin and mucous membranes, as well as pain; also called urticant. (Note that in this database, nettle agents are included in the Blister Agent category.)
Neuromyopathy	A disease of the nerves and associated muscle tissue.
Neuropathy	A disease or abnormality of the nervous system.
Neuropsychiatric	In medicine, pertaining to disorders with both neurological and psychiatric features.
Neutralization	The state or quality of being neutralized. A reaction between an acid and a base that yields a salt and water.
NFPA	National Fire Protection Association
NFPA 704	Standard System for the Identification of the Hazards of Materials for Emergency Response. A standard providing a readily recognized, easily understood system for identifying specific hazards and their severity using spatial, visual, and numerical methods to describe in simple terms the relative hazards of a material. It addresses the health, flammability, instability, and related hazards that may be presented as short-term, acute exposures that are most likely to occur as a result of fire, spill, or similar emergency.
NFPA 704 Flammability	The red (upper) quadrant of the NFPA 704 symbol. The values are: 4 – Danger. Flammable gas or extremely flammable liquid. 3 – Warning. Flammable liquid, flash point below 100°F (38°C). 2 – Caution. Combustible liquid, flash point of 100° to 200°F (38° to 93°C). 1 – Combustible if heated. 0 – Not combustible.
NFPA 704 Health	The blue (left-hand) quadrant of the NFPA 704 symbol. The values are: 4 – Danger. May be fatal on short exposure. Specialized protective equipment required. 3 – Warning. Corrosive or toxic. Avoid skin contact or inhalation. 2 – Warning. May be harmful if inhaled or absorbed 1 – Caution. May be irritating. 0 – No unusual hazard.
NFPA 704 Reactivity	The yellow (right-hand) quadrant of the NFPA 704 symbol. The values are: 4 – Danger. Explosive material at room temperature 3 – Danger. May be explosive if shocked, heated under confinement or mixed with water. 2 – Warning. Unstable or may react violently if mixed with water. 1 – Caution. May react if heated or mixed with water, but not violently. 0 – Stable. Not reactive when mixed with water.
NFPA 704 Special	The white (lower) quadrant of the NFPA 704 symbol. The values are: W – Water Reactive. OX – Oxidizing Agent.
NIOSH	National Institute for Occupational Safety and Health.
Non-polar	Not polar; not having an electric charge.
Not established/determined	This term is used when information is not available for a given agent.
Not Recommended	This term is used when there is insufficient data for the agent.
NPO	Nothing by mouth; from the Latin nil per os. May also be written n.p.o.
NPPTL	National Personal Protective Technology Laboratory
Nucleophile	A chemical compound or group that is attracted to nuclei and tends to donate or share electrons.
Nystagmus	Involuntary movement (oscillation) of the eyeballs.

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O

O

Terms	Description
Ocular	Of or relating to the eye.
Off-gassing	The release of chemicals from non-metallic substances under ambient or greater pressure conditions.
Oliguria	Reduced excretion of urine.
Opacification	The act or process of becoming opaque; clouding.
Opaque	Impenetrable by light; neither transparent nor translucent.
Ophthalmic	Of or relating to the eye; ocular.
Ophthalmologist	A physician who specializes in ophthalmology, the treatment of diseases and conditions of the eye.
Opiate	A drug, hormone, or other chemical substance having sedative or narcotic effects similar to those from substances containing opium or its derivatives.
Opioid	A synthetic substance with opiate-like qualities.
Opisthotonos	A condition of spasm of the muscles of the back, which causes the body to arch backwards in hyperextension, e.g. during convulsions or seizures.
Optic neuritis	Inflammation of the optic nerve.
Optic neuropathy	Degeneration of the optic nerve.
Organ congestion	Accumulation of blood in the organs.
Organophosphate	An organophosphorus compound.
Organophosphorus	Of, relating to, or being a phosphorus-containing organic pesticide (as malathion) that acts by inhibiting cholinesterase.
Oropharyngeal	The part of the pharynx between the soft palate and the epiglottis.
OSHA	Occupational Safety and Health Administration.
Osteosclerosis	Abnormal hardening of the bone or bone marrow.
Oxidant	A substance that oxidizes another substance; an oxidizing agent.
Oxidation	Generally, the chemical reaction of a substance with oxygen (O2) or an oxygen-containing material, which adds oxygen atom(s) to the compound being oxidized. More rigorously, “the loss of electrons from an atom, compound or molecule.” Oxidation reactions frequently generate heat (are exothermic).
Oxidizer	A substance that oxidizes another substance, especially one that supports the combustion of fuel; an oxidizing agent.
Oxidizing agent	A substance that oxidizes another substance. Oxdizing agents can cause other materials to combust more readily (or upon contact) or make fires burn more strongly.

P

P

Terms	Description
Pallor	Deficiency of color especially of the face; paleness.
Palpitation	Irregular, rapid beating or pulsation of the heart.
Pancreatitis	Inflammation of the pancreas.
Pancytopenia	An abnormal reduction in the number of red blood cells, white blood cells, and blood platelets in the blood.
Paralysis	Loss or impairment of the ability to move a body part, usually as a result of damage to its nerve supply.
Parenteral	introduced otherwise than by way of the intestines, e.g., parenteral drug administration can be by intravenous, intramuscular, or subcutaneous injection
Paresthesia	Sensation of prickling tingling or creeping on the skin, with no apparent physical cause.
Parkinsonism	A condition causing tremor and weakness of the resting muscles and shuffling gait.
Paroxysmal	Suddenly recurring or intensifying (e.g., pain or symptoms).
PEL	OSHA Permissible Exposure Limit.
Pellet	A small, solid or densely packed ball or mass.
Peripheral	Related to, located in, or constituting an outer boundary, surface, or periphery.
Peripheral Nervous System	The part of the nervous system that is outside the central nervous system and comprises the cranial nerves (except the optic nerve), the spinal nerves, and the autonomic nervous system.
Peripheral neuropathy	Degeneration of certain nerves.
Perseveration	Continual, involuntary repetition of behaviors.
Pesticide	A pesticide is any substance or mixture of substances intended to be used to control, repel, or kill any pest. Pests compete with humans for food, destroy property, spread disease, or are considered a nuisance. They include insects, mice and other animals, unwanted plants (weeds), fungi, or microorganisms like bacteria and viruses. (U.S. EPA)
Pharyngitis	Inflammation of the throat (pharynx).
Phenytoin	An anticonvulsant drug used most commonly in the treatment of epilepsy. Also called diphenylhydantoin.
Photophobia	A painful sensitivity to light.
Platelet	A minute body found in the blood of mammals that functions to promote blood clotting; also called thrombocyte.
Pneumonia	An inflammatory lung disease (see also pneumonitis).
Pneumonitis	A disease characterized by inflammation of the lungs (see also pneumonia).
Pocket resuscitation mask	A device that protects a rescuer from being contaminated by a victim when giving emergency mouth-to-mouth resuscitation. It consists of a curved plastic cup that rests over a victim’s mouth and has a short tube attached for the rescuer to blow into.
Poison or Poisonous	The words “poison” or “poisonous” are synonymous with the word “toxic”.
Polar	Exhibiting polarity, i.e., having electric charges.
Polydipsia	Excessive thirst.
Polymerized	Having undergone polymerization, a process in which two or more smaller molecules are joined to form larger molecules that contain repeating structural units.
Polyneuropathy	A degenerative disease of the nerves.
Positive Pressure Self-Contained Breathing Apparatus (SCBA)	An apparatus providing a constant, positive pressure flow of air within the face piece, even if one inhales deeply while doing heavy work. Use apparatus certified by NIOSH and the Department of Labor/Mine Safety and Health Administration in accordance with 42 CFR Part 84. Use it in accordance with the requirements for respiratory protection specified in OSHA 29 CFR 1910.134 (Respiratory Protection) and/or 29 CFR 1910.156 (f) (Fire Brigades Standard).
Powered Air-Purifying Respirator (PAPR)	A motorized respirator system that uses a filter to clean surrounding air before deliveringto the wearer to breathe. It typically includes a blower/battery box worn on the belt, headpiece, and breathing tube.
ppm	Parts per million.
Prodromal syndrome	Premonitory or precursory symptoms.
Proptosis	Abnormal bulging (forward projection) of the eyeball.
Prostration	Complete physical or mental exhaustion.
Proteinuria	The presence of excess protein in the urine.
Pruritus	Severe itching.
Pseudomembrane	A false membrane or fibrous deposit formed in some disease processes.
psia	A unit of pressure, pounds per square inch absolute
psig	A unit of pressure, pounds per square inch gauge
Psychic	Of or relating to the mind; mental.
Psychosis	A serious mental disorder.
Ptosis	Drooping of the upper eyelid.
Ptyalism	Excessive salivation.
Pulmonary	Related to or associated with the lungs.
Pulmonary aspiration	The inhalation of foreign materials such as stomach contents into the lungs.
Pulmonary edema	Accumulation of fluid in the lungs.
Pulmonary fibrosis	An increase in fibrous tissue in the lungs.
Pulmonary hemorrhage	Bleeding in the lungs.
Pulmonary hypertension	High blood pressure in the lungs.
Pulmonary thrombosis	The presence of blood clots in the lungs.
Pungent	Affecting the organs of taste or smell with a sharp acrid sensation.
Pustular	Containing pus.
Pustule	A small elevation of the skin containing pus and having an inflamed base.
PVC	A polymer of vinyl chloride used instead of rubber in electric cables.

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Q

Q

Terms	Description
QID	Four times per day or four daily doses; from the Latin quater in die. May also be written q.i.d.

R

R

Terms	Description
RADS	Reactive Airways Dysfunction Syndrome.
Rales	An abnormal respiratory sound.
Red Zone	Areas where significant contamination with chemical, biological, radiological, or nuclear (CBRN) agents has been confirmed or is strongly suspected but area has not been characterized. The Area is presumed to be life threatening from both skin contact and inhalation.
Refractory	Resistant to treatment or cure.
Refractory cardiogenic shock	Shock resulting from failure of the heart’s ability to pump sufficient blood.
REL	NIOSH Recommended Exposure Limit. The designation “(skin)” in this section “indicates the potential for dermal absorption; skin exposure should be prevented as necessary through the use of good work practices and gloves, coveralls, goggles, and other appropriate equipment,” according to the NIOSH Pocket Guide to Chemical Hazards.
Renal	Of, relating to, or in the region of the kidneys.
Renal failure	Kidney failure.
Residual	The quantity left over at the end of a process.
Respiration	The act of breathing. The physical and chemical process by which an organism supplies its cells and tissues with the oxygen needed for metabolism and relieves them of the carbon dioxide formed in energy-producing reactions.
Respirator	A device (“approved”) that has met the requirements of 42 CFR part 84, has been designed to protect the wearer from inhalation of harmful atmospheres, and has been approved by the National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Administration (MSHA).
Respiratory depression	Reduced respiratory function.
Respiratory failure	The loss of lung function, either acute or chronic, that results in subnormal oxygenation of blood or abnormally increased carbon dioxide. The inability to breathe by a person’s own means.
Resuscitation	Restoration of consciousness.
Retinal hemorrhage	Bleeding of the membrane in the rear of the eye.
Rhabdomyolysis	Destruction or degeneration of skeletal muscle tissue.
Rhinorrhea	Runny nose; excessive secretion of mucus from the nose.
Rhonchi	A coarse rattling sound somewhat like snoring, usually caused by secretion in a bronchial tube.
Riot Control/Tear agent	A substance that causes intense irritation to the eyes and upper respiratory tract, including profuse tearing.
Risus sardonicus	Muscle spasm resulting in distortion of the face into a grinning expression, such as during convulsions or seizures.
RTECs	Registry of Toxic Effects of Chemical Substances (RTECS).

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S

S

Terms	Description
SCBA	Self-Contained Breathing Apparatus.
Sedation	Induced state of relaxation, especially by the use of sedative drugs.
Seizure	A sudden attack (as of a disease). A sudden change in behavior due to excessive electrical activity in the brain.
Self-Contained Breathing Apparatus (SCBA)	A respiratory filter mask that contains its own air supply. It is composed of a face piece connected by a hose to a wearable, compressed, clean-air supply pack much like a scuba tank.
Sepsis	A toxic condition resulting from the spread of infection.
Sequela	A secondary consequence or result; aftereffect. (Plural = sequelae.)
Serum	The clear yellowish fluid obtained upon separating whole blood into its solid and liquid components after it has been allowed to clot. Also called blood serum.
Severe	Serious (for a health effect); of high intensity (for an exposure).
Shock	A state of profound depression of the vital processes of the body that is characterized by paleness (pallor), rapid but weak pulse, rapid and shallow respiration, reduced total blood volume, and low blood pressure and that is caused usually by severe especially crushing injuries, hemorrhage, burns, or major surgery.
Short-Term Exposure Limit (STEL)	An airborne exposure limit designed to address short-term upward deviations in exposure. Typically, exposures at the STEL should not be longer than 15 minutes and should not occur more than 4 times per day, and at least 60 minutes should elapse between successive exposures in this range.
Sloughing	Separating or casting off dead tissue from living tissue, as in a wound.
Slurry	A thin mixture of a liquid, especially water, and any of several finely divided insoluble substances.
Sodium hypochlorite	The active ingredient in household liquid chlorine bleach. It is ordinarily about 5% strength in a water-based solution of bleach.
Somatic	Pertaining to or characteristic of the body (physical).
Somnolence	A state of abnormal drowsiness (see also lethargy).
Sorbent	A substance that takes up and holds, e.g., liquids, by absorption or adsorption.
Spasm	Abnormal and involuntary contraction of a muscle or of a hollow organ (such as an artery).
Spasmodic	Relating to, characterized by, or resulting from spasm.
Spermatogenesis	Formation and development of spermatozoa.
Sputum	Matter ejected from the lungs and air passages during cough.
Stabilizer	A substance that renders or maintains a solution, mixture, suspension, or state resistant to chemical change.
STB	Super Tropical Bleach slurry.
STEL	See: Short-Term Exposure Limit.
Stomatitis	Inflammatory disease of the mouth.
Street Clothing and Work Uniforms	These garments, such as uniforms worn by police and emergency medical services personnel, provide almost no protection from the harmful effects of dangerous goods.
Stricture formation	Abnormal narrowing of the digestive tract.
Structural Fire Fighters’ Protective Clothing (SFPC)	Turnout or bunker gear; the protective clothing normally worn by fire fighters during structural fire fighting operations. It includes a helmet, coat, pants, boots, gloves and a hood to cover parts of the head not protected by the helmet and face piece. This clothing must be used with full-face piece positive pressure self-contained breathing apparatus (SCBA).
Stupor	A state of diminished responsiveness and impaired consciousness.
Subacute	Less marked than acute in character; falling between acute and chronic in nature.
Subcutaneous	Located or placed just beneath the skin.
Sublethal	Slightly less than lethal; e.g., less than the amount of an agent required to cause death
Sublime	To pass directly from the solid to the vapor state and condense back to solid form.
Suffocation	Sensation of inability to get enough air.
Syncope	A brief loss of consciousness caused by a temporary deficiency of oxygen in the brain; a black out; fainting.
Synesthesias	Mixed sensory perceptions (e.g., seeing sounds or feeling colours).
Synthetic	Produced artificially; not of natural origin.
Systemic	Affecting the body generally; not localized.
Systemic agent	A substance with whole-body (systemic) or multi-organ-system effects. This category includes so-called “Blood Agents,” as well as other agents with systemic effects.
Systemic toxicity	Whole-body toxicity.

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T

T

Terms	Description
T wave	The third and last common wave in an electrocardiogram. It reflects the electrical activity produced when the ventricles are recharging for the next contraction (repolarizing)./td>
Tachycardia	A rapid heart rate, especially one above 100 beats per minute in an adult.
Tachypnea	Rapid breathing.
TEEL	Department of Energey Temporary Emergency Exposure Limit
TEEL-0	The threshold concentration below which most people will experience no appreciable risk of health effects.
TEEL-1	The maximum concentration in air below which it is believed nearly all individuals could be exposed without experiencing other than mild transient adverse health effects or perceiving a clearly defined objectionable odor.
TEEL-2	The maximum concentration in air below which it is believed nearly all individuals could be exposed without experiencing or developing irreversible or other serious health effects or symptoms that could impair their abilities to take protective action.
TEEL-3	The maximum concentration in air below which it is believed nearly all individuals could be exposed without experiencing or developing life-threatening health effects.
Tepid	Lukewarm (referring to liquids)
Tetany	An abnormal phase of prolonged muscular contractions.
Thrombocyte	A type of blood cell, also called platelet.
Thrombocytopenia	An abnormal decrease in the number of platelets in circulating blood.
Thrombosis	The formation or presence of blood clots.
Time-weighted average (TWA)	An average value of exposure over the course of an 8-hour (typically) work shift
Tinnitus	A sound in one ear or both ears, such as buzzing, ringing, or whistling.
Totally-Encapsulating Chemical Protective (TECP) Suit	A full body garment which is constructed of protective clothing materials; covers the wearer’s torso, head, arms, legs and respirator; may cover the wearer’s hands and feet with tightly attached gloves and boots; completely encloses the wearer and respirator by itself or in combination with the wearer’s gloves and boots.
Toxic	Poisonous, injurious to health or dangerous to life.
Toxic Inhalation Hazard (TIH)	Term used in the U.S. Department of Transportation ERG 2000 guidebook to describe gases and volatile liquids that are toxic when inhaled.
Toxicity	The quality, state, or relative degree of being toxic or poisonous.
Toxin	A poisonous substance formed during the metabolism and growth of certain living microorganisms and some plants and animals. It is usually very unstable, notably toxic when introduced into the tissues, and typically capable of inducing antibody formation.
Transdermal	Through or by way of the skin, such as a skin patch.
Transfusion	The transfer of whole blood or blood products from one individual to another.
Transient	Existing temporarily; passing away in time.
Triage	A process for sorting injured people into groups based on their need for or likely benefit from immediate medical treatment. Triage is used in hospital emergency rooms, on battlefields, and at disaster sites when limited medical resources must be allocated.
Trismus	Muscle spasm which causes the jaw to be rigidly clamped, such as during convulsions or seizures.
TWA	See: Time-weighted average.

U

U

Terms	Description
Ulcer	A break in skin or mucous membrane with loss of surface tissue, disintegration and death of tissue, and often pus.
Ulceration	Tissue damage (e.g., of the cornea, airway lining, stomach or intestine lining).
Unknown	This term is used when information for a section has not been identified for the agent.
Urticant	An agent that causes severe irritation to the skin and mucous membranes, as well as pain; also called nettle agent.
Urticaria	Hives.

V

V

Terms	Description
Vapor	The state of a substance that exists below its critical temperature and that may be liquefied by application of sufficient 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.
Vaporize	To convert into vapor, as by the application of heat, whether naturally or artificially.
Vascular collapse	Collapse of the blood vessels.
Vasoconstriction	Narrowing of the interior diameter of blood vessels.
Vasodilation	Widening of the interior diameter of blood vessels.
Vasopressor	Of, relating to, or causing constriction of blood vessels, and thereby an increase in blood pressure.
Ventilation	The circulation and exchange of gases in the lungs that is basic to respiration.
Vermiculite	A lightweight, highly absorbent material made from mica.
Vertigo	A sensation that one’s self or one’s surroundings are whirling dizzily.
Vesicant	An agent that produces blisters on exposed tissue.
Vesication	Formation of blisters; blistering.
Vesicular	Blister-like.
Volatile	Evaporating readily at normal temperatures and pressures.
Vomiting agent	An agent that causes exposed persons to vomit.
Vomitus	Vomited matter.

W

W

Terms	Description
Water spray (fog)	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. (From U.S. DOT ERG 2000)
Wheal	A small elevation or swelling on the skin that usually itches or burns.
Worker population limit (WPL)	An airborne exposure limit designed to protect workers. It is expressed as a time-weighted average (TWA) for exposure over an 8-hour work shift.
WPL	See: Worker population limit.

X

X

Terms	Description
Xerostomia	Abnormal dryness of the mouth.

Y

Y

Terms	Description
Yellow Zone	Areas where contamination with chemical, biological, radiological, or nuclear (CBRN) agents is possible but active release has ended and initial monitoring exists.

Z

Z

Terms	Description
µg	Microgram; one-millionth of a gram.

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