Very important Safety Terms & Definitions

abatement period: The amount of time given an employer to correct a hazardous condition that has been cited.
abrasive blasting: A process for cleaning surfaces by means of materials such as sand, alumina, or
steel grit in a stream of high-pressure air.
absorption:The taking up of one substance by another,such as a liquid by a solid or a gas by a liquid.
accident: This term is often misunderstood and is often mistakenly used interchangeably with
injury. The dictionary defines an accident as “a happening or event that is not expected,
foreseen or intended.”The legal definition is:“an unexpected happening causing loss or injury
which is not due to any fault or misconduct on the part of the person injured,yet entitles some
kind of legal relief.”
Consider the confusion in the following definition of the term accident:
With rare exception, an accident is defined, explicitly or implicitly, by the unexpected
occurrence of physical or chemical change to an animate or inanimate structure. It is
important to note that the term covers only damage of certain types. Thus, if a person is
injured by inadvertently ingesting poison, an accident is said to have taken place; but if the
same individual is injured by inadvertently ingesting poliovirus,the result is but rarely con-
sidered accidental. This illustrates a curious inconsistency in the approach to accidents as
opposed to other sources of morbidity, one which continues to delay progress in the field
[of accident research].In addition,although accidents are defined by the unexpected occur-
rence of damage, it is the unexpectedness, rather than the production and prevention of
that damage per se, that has been emphasized by much of accident research. (Haddon,
Suchm,and Klein,1964,28)
However, another definition—the one we will adopt, the one that is more applicable to
our context—is provided by safety experts, the authors of The Dictionary of Terms Used in
the Safety Profession (ASSE, 1988). Let’s see how they define accident.
An accident is an unplanned and sometimes injurious or damaging event which interrupts
the normal progress of an activity and is invariably preceded by an unsafe act or unsafe con-
dition thereof. An accident may be seen as resulting from a failure to identify a hazard or
from some inadequacy in an existing system of hazard controls. Based on applications in
casualty insurance, an accident is an event that is definite in point of time and place but
unexpected as to either its occurrence or its results.

accident analysis: A comprehensive, detailed review of the data and information compiled from
an accident investigation.An accident analysis should be used to determine causal factors only,
and not to point the finger of blame at any one.Once the causal factors have been determined,
corrective measures should be prescribed to prevent recurrence.
accident prevention: The act of prevention of a happening which may cause loss or injury to a
person.
accommodation: The ability of the eye to become adjusted after viewing the visual display
terminal (VDT) so as to be able to focus on other objects, particularly objects at a distance.
accuracy: The exactness of an observation obtained from an instrument or analytical technique
with the true value.
ACGIH: American Conference of Governmental Industrial Hygienists.

acid: Any chemical with a low pH that in water solution can burn the skin or eyes.Acids turn
litmus paper red and have pH values of 0 to 6.
acoustics: In general,the experimental and theoretical science of sound and its transmission; in
particular, that branch of the science that has to do with the phenomena of sound in a
particular space such as a room or theater. Industrial hygiene is concerned with the technical
control of sound,and,to engineer out the noise hazard,involves architecture and construction,
studying control of vibration, soundproofing, and the elimination of noise.
action level: Term used by OSHA and NIOSH (National Institute for Occupational Safety and
Health—a federal agency that conducts research on safety and health concerns) and is defined
in the Code of Federal Regulations (CFR), title 40,Protection of Environment. Under OSHA,
action level is the level of toxicant, which requires medical surveillance,usually 50% of the
Personal Exposure Level (PEL).Note that OSHA also uses the action level in other ways besides
setting the level of“toxicant.”For example,in its hearing conservation standard,29 CFR
1910.95,OSHA defines the action level as an 8-hour time-weighted average (TWA) of 85
decibels measured on the A-scale, slow response, or equivalently, a dose of 50%. Under 40 CFR
763.121,action level means an airborne concentration of asbestos of 0.1 fiber per cubic
centimeter (f/cc) of air calculated as an 8-hour TWA.

activated charcoal: Charcoal is an amorphous form of carbon formed by burning wood,nutshells, animal bones, and other carbonaceous material. Charcoal becomes activated by
heating it with steam to 800–900°C.During this treatment,a porous,submicroscopic internal
structure is formed which gives it an extensive internal surface area.Activated charcoal is
commonly used as a gas or vapor adsorbent in air-purifying respirators and as a solid sorbent in
air-sampling.

acute: Health effects,which show up a short length of time after exposure.An acute exposure runs
a comparatively short course and its effects are easier to reverse than those of a chronic
exposure.
acute toxicity: The discernible adverse effects induced in an organism with a short period of time
(days) of exposure to an agent.
administrative controls: Methods of controlling employee exposures by job rotation,work
assignment, time periods away from the hazard, or training in specific work practices designed
to reduce exposure.

adsorption: The taking up of a gas or liquid at the surface of another substance,usually a solid
(e.g., activated charcoal adsorbs gases).
aerosols: Liquid or solid particles that are so small they can remain suspended in air long enough
to be transported over a distance.
air: The mixture of gases that surrounds the earth; its major components are as follows: 78.08%
nitrogen, 20.95% oxygen, 0.03% carbon dioxide, and 0.93% argon.Water vapor (humidity) varies.
air cleaner: A device designed to remove atmospheric airborne impurities,such as dusts,gases,
vapors,fumes,and smoke.
air contamination: The result of introducing foreign substances into the air so as to make the air
contaminated.
air-line respirator: A respirator that is connected to a compressed breathing air source by a hose
of small inside diameter. The air is delivered continuously or intermittently in a sufficient
volume to meet the wearer’s breathing.
air monitoring: The sampling for and measurement of pollutants in the atmosphere.
air pollution: Contamination of the atmosphere (indoor or outdoor) caused by the discharge
(accidental or deliberate) of a wide range of toxic airborne substances.
air-purifying respirator:A respirator that uses chemicals to remove specific gases and vapors
from the air or that uses a mechanical filter to remove particulate matter.An air-purifying
respirator must only be used when there is sufficient oxygen to sustain life and the air
contaminant level is below the concentration limits of the device.
air sampling: Industrial hygienists are interested in knowing what contaminants workers are
exposed to, and at what concentrations. Determining the quantities and types of atmospheric
contaminants is accomplished by measuring and evaluating a representative sample of air.The
types of air contaminants that occur in the workplace depend upon the raw materials used and
the processes employed.Air contaminants can be divided into two broad groups,depending
upon physical characteristics: (1) gases and vapors, and (2) particulates.

air-supplied respirator: Respirator that provides a supply of breathable air from a clean source
outside of the contaminated work area.

allergic reactions: Due to the presence of allergens on spores, all molds studied to date have the
potential to cause allergic reaction in susceptible humans.Allergic reactions are believed to be
the most common exposure reaction to molds (Rose, 1999).
alpha particle: A small, positively charged particle made up of two neutrons and two protons of
very high velocity,generated by many radioactive materials,including uranium and radium.
alveoli: Tiny air sacs in the lungs,located at the ends of bronchioles.Through the thin walls of the
alveoli,blood takes in oxygen and gives up carbon dioxide in respiration.
ambient: Descriptive of any condition of the surrounding environment at a given point. For
example, ambient air means that portion of the atmosphere, external to buildings, to which the
general public has access.Ambient sound is the sound generated by the environment.
amorphous: Noncrystalline.
ANSI: The American National Standards Institute is a voluntary membership organization (run
with private funding) that develops consensus standards nationally for a wide variety of devices
and procedures.
aromatic: Applied to a group of hydrocarbons and their derivatives characterized by the presence
of the benzene nucleus.
asbestosis: A disease of the lungs caused by inhalation of fine airborne asbestos fibers.
asphyxiant: A vapor gas which can cause unconsciousness or death by suffocation (lack of
oxygen).
asphyxiation: Suffocation from lack of oxygen.A substance (e.g., carbon monoxide), that
combines with hemoglobin to reduce the blood’s capacity to transport oxygen produces
chemical asphyxiation. Simple asphyxiation is the result of exposure to a substance (such as
methane) that displaces oxygen.Asphyxiation is one the principal potential hazards of working
in confined spaces.
ASTM: American Society for Testing and Materials.
atmosphere: In physics, a unit of pressure whereby 1 atmosphere (atm) equals 14.7 pounds per
square inch (psi).
atmosphere-supplying respirator: A respirator that provides breathing air from a source
independent of the surrounding atmosphere.There are two types: air-line and self-contained
breathing apparatus.

atmospheric pressure: The pressure exerted in all directions by the atmosphere.At sea level,mean
atmospheric pressure is 29.92 in. H, 14.7 psi, or 407 in. wg.
atomic weight: The atomic weight is approximately the sum of the number of protons and
neutrons found in the nucleus of an atom. This sum is also called the mass number. The atomic
weight of oxygen is approximately 16, with most oxygen atoms containing 8 neutrons and
8 protons.
attenuate: To reduce in amount. Used to refer to noise or ionizing radiation.
attenuation: The reduction of the intensity at a designated first location as compared with
intensity at a second location,which is farther from the source (reducing the level of noise by
increasing distance from the source is a good example).
audible range: The frequency range over which normal hearing occurs—approximately 20 Hz
through 20,000 Hz.Above the range of 20,000 Hz,the term ultrasonic is used.Below 20 Hz,the
term subsonic is used.
audiogram: A record of hearing loss or hearing level measured at several different frequencies—
usually 500 to 6000 Hz.The audiogram may be presented graphically or numerically.Hearing
level is shown as a function of frequency.
audiometric testing: Objective measuring of a person’s hearing sensitivity.By recording the
response to a measured signal,a person’s level of hearing sensitivity can be expressed in
decibels, as related to an audiometric zero, or no-sound base.
authorized person: A person designated or assigned by an employer or supervisor to perform a
specific type of duty or duties,to use specified equipment,and/or to be present in a given
location at specified times (for example,an authorized or qualified person is used in confined
space entry).
auto-ignition temperature: The lowest temperature at which a vapor-producing substance or a
flammable gas will ignite even without the presence of a spark or flame.
Avogadro’s Number: The number of molecules in a mole of any substance (6.02217 × 10 3 ).
Named after Italian physicist Amedeo Avogadro (1776–1856).At 0°C and 29.92 in.HG,one
mole occupies 22.4 liters of volume.
background noise:The radiation coming from sources other than the particular noise sources being
monitored.
baghouse: Term commonly used for the housing containing bag filters for recovery of fumes from
arsenic,lead,sulfa,etc.It has many different trade meanings,however.
base:A compound that reacts with an acid to form a salt.It is another term for alkali.
baseline data: Data collected prior to a project for later use in describing conditions before the
project began.Also commonly used to describe the first audiogram given (within six months)
to a worker after he or she has been exposed to the action level (85 dBA)—to establish his or her
baseline for comparison to subsequent audiograms for comparison.
bel: A unit equal to 10 decibels (see decibel).
behavior-based management models: A management theory, based on the work of B. F. Skinner,
that explains behavior in terms of stimulus,response,and consequences.
benchmarking: A process for rigorously measuring company performance versus “best-in-class”
companies,and using analysis to meet and exceed the best in class.
benign: Not malignant.A benign tumor is one which does not metastasize or invade tissue.
Benign tumors may still be lethal,due to pressure on vital organs.
beta particle: Beta radiation.A small electrically charged particle thrown off by many radioactive
materials,identical to the electron.Beta particles emerge from radioactive material at high speeds.
bioaerosols: Mold spores, pollen, viruses, bacteria, insect parts, animal dander, etc.
biohazard: Biological hazard—organisms or products of organisms that present a risk to humans.
boiler code: ANSI/ASME Pressure Vessel Code.A set of standards prescribing requirements for the
design,construction,testing,and installation of boilers and unfired pressure vessels.
boiling point: The temperature at which the vapor pressure of a liquid equals atmospheric
pressure.
Boyle’s Law: States that the product of a given pressure and volume is constant with a constant
temperature.
breathing zone: A hemisphere-shaped area from the shoulders to the top of the head.
cancer:A cellular tumor formed by mutated cells.
capture velocity: Air velocity at any point in front of an exhaust hood necessary to overcome
opposing air currents and to capture the contaminated air by causing it to flow into the hood.
carbon monoxide: A colorless, odorless toxic gas produced by any process that involves the
incomplete combustion of carbon-containing substances. It is emitted through the exhaust of
gasoline powered vehicles.
carcinogen: A substance or agent capable of causing or producing cancer in mammals, including
humans.A chemical is considered to be a carcinogen if: (a) it has been evaluated by the
International Agency for Research on Cancer (IARC) and found to be a carcinogen or potential
carcinogen; (b) it is listed as a carcinogen or potential carcinogen in the Annual Report on
Carcinogens published by the National Toxicology Program (NTP) (latest edition); or (c) it is
regulated by OSHA as a carcinogen.
carpal tunnel syndrome: An injury to the median nerve inside the wrist.
CAS: Chemical Abstracts Service,an organization under the American Chemical Society.CAS
abstracts and indexes chemical literature from all over the world in Chemical Abstracts.“CAS
Numbers”are used to identify specific chemicals or mixtures.
catalyst:A substance that alters the speed of,or makes possible,a chemical or biochemical
reaction,but remains unchanged at the end of the reaction.
catastrophe: A loss of extraordinary large dimensions in terms of injury, death, damage, and destruction.
causal factor: A person, thing, or condition that contributes significantly to an accident or to a
project outcome.
ceiling limit (C): An airborne concentration of a toxic substance in the work environment, which
should never be exceeded.
CERCLA: Comprehensive Environmental Response, Compensation and Liability Act of 1980.
Commonly known as “Superfund.”
CFR: Code of Federal Regulations.A collection of the regulations that have been promulgated
under U.S. law.
Charles’s Law: Law stating that the volume of a given mass of gas at constant pressure is directly
proportional to its absolute temperature (Kelvin).
Chemical cartridge respirator: A respirator that uses various chemical substances to purify
inhaled air of certain gases and vapors.This type respirator is effective for concentrations no
more than ten times the TLV of the contaminant,if the contaminant has warning properties
(odor or irritation) below the TLV.
chemical change: Change that occurs when two or more substances (reactants) interact with each
other, resulting in the production of different substances (products) with different chemical compositions.A simple example of chemical change is the burning of carbon in oxygen to
produce carbon dioxide.
chemical hazards: Include mist, vapors, gases, dusts, and fumes.
chemical spill: An accidental dumping,leakage,or splashing of a harmful or potentially harmful
substance.
CHEMTREC: Chemical Transportation Emergency Center. Public service of the Chemical
Manufacturers Association that provides immediate advice for those at the scene of hazardous
materials emergencies.CHEMTREC has a 24-hour toll-free telephone number (800-424-9300)
to help respond to chemical transportation emergencies.
chromatograph: An instrument that separates and analyzes mixtures of chemical substances.
chronic:Persistent,prolonged,repeated.Chronic exposure occurs when repeated exposure to or
contact with a toxic substance occurs over a period of time,the effects of which become evident
only after multiple exposures.
coefficient offriction:A numerical correlation ofthe resistance ofone surface against another surface.
colorimetry:A term used for all chemical analysis involving reactions in which a color is
developed when a particular contaminant is present in the sample and reacts with the collection
medium.The resultant stain length or color intensity is measured to determine the actual
concentration.
combustible gas indicator: An instrument which samples air and indicates whether an explosive
mixture is present.
combustible liquid: Liquids having a flash point at or above 37.8°C (100°F).
combustion: Burning,defined in chemical terms as the rapid combination of a substance with
oxygen, accompanied by the evolution of heat and usually light.
competent person: As defined by OSHA,one who is capable of recognizing and evaluating
employee exposure to hazardous substances or to unsafe conditions,and who is capable
of specifying protective and precautionary measures to be taken to ensure the safety of
employees as required by particular OSHA regulations under the conditions to which such
regulations apply.
concentration: The amount of a given substance in a stated unit of measure.Common methods
of stating concentration are percent by weight or by volume, weight per unit volume,
normality, etc.
conductive hearing loss: Type of hearing loss usually caused by a disorder affecting the middle or
external ear.
confined space:A vessel,compartment,or any area having limited access and (usually) no
alternate escape route, having severely limited natural ventilation or an atmosphere containing
less that 19.5% oxygen,and having the capability of accumulating a toxic,flammable,or
explosive atmosphere,or of being flooded (engulfing a victim).
contact dermatitis: Dermatitis caused by contact with a substance.
containment: In fire terminology, restricting the spread of fire. For chemicals, restricting
chemicals to an area that is diked or walled off to protect personnel and the environment.
contingency plan: (commonly called the emergency response plan) Under 40 CFR 260.10,a
document that sets forth an organized,planned,and coordinated course of action to be
followed in the event of an emergency that could threaten human health or the environment.
convection: The transfer of heat from one location to another by way of a moving medium.
corrosive material: Any material that dissolves metals or other materials,or that burns the skin.
coulometer: A chemical analysis instrument that determines the amount of a substance released
in electrolysis by measurement of the quantity of electricity used.The number of electrons
transferred in terms of coulombs is an indication of the contaminant concentration.
cumulative injury: A term used to describe any physical or psychological disability that results
from the combined effects of related injuries or illnesses in the workplace.
cumulative trauma disorder (CTD): A disorder of a musculoskeletal or nervous system
component,which in some cases can result in moderate to total disability.It is caused by highly
repetitive and/or forceful movements required of one or more parts of the worker’s
musculoskeletal system.
cutaneous: Pertaining to or affecting the skin.
cyclone device:A dust-collecting instrument that has the ability to separate particles by size.
Dalton’s Law of Partial Pressures: States that in a mixture of theoretically ideal gases,the
pressure exerted by the mixture is the sum of the pressure exerted by each component gas of
the mixture.
decibel (dB): A unit of measure used originally to compare sound intensities and subsequently
electrical or electronic power outputs; now also used to compare voltages. In hearing
conservation,a logarithmic unit used to express the magnitude of a change in level of sound
intensity.
decontamination: The process of reducing or eliminating the presence of harmful substances
such as infectious agents,to reduce the likelihood of disease transmission from those
substances.
degrees Celsius (Centigrade): The temperature on a scale in which the freezing point of water is
0°C and the boiling point is 100°C.To convert to degrees Fahrenheit,use the following formula:
°F = (°C × 1.8) + 32.
degrees Fahrenheit: The temperature on a scale in which the boiling point of water is 212°F and
the freezing point is 32°F.
density: A measure of the compactness of a substance; it is equal to its mass per unit volume and
is measured in kg per cubic meter/LB per cubic foot (D = mass/Volume).
dermatitis: Inflammation or irritation of the skin from any cause. Industrial dermatitis is an
occupational skin disease.
dermatosis: A broader term than dermatitis; it includes any cutaneous abnormality, thus
encompassing folliculitis,acne,pigmentary changes,and nodules and tumors.
design load: The weight that can be safely supported by a floor, equipment, or structure, as
defined by its design characteristics.
dike: An embankment or ridge of either natural or man-made materials used to prevent the
movement of liquids, sludges, solids, or other materials.
dilute: Adding material to a chemical by the user or manufacturer to reduce the concentration of
active ingredient in the mixture.
direct reading instruments: Devices that provide an immediate indication of the concentration of
aerosols, gases, and vapors by means of a color change in colorimetric devices, or a register on a
meter or instrument.

dose: An exposure level. Exposure is expressed as weight or volume of test substance per volume
of air (mg/l), or as parts per million (ppm).
dose-response relationship: Correlation between the amount of exposure to an agent or toxic
chemical and the resulting effect on the body.
dosimeter: Provides a time-weighted average over a period of time such as one complete work shift.
dry bulb temperature: The temperature of a gas or mixture of gases indicated on an ordinary
thermometer after correction for radiation and moisture.
duct: A conduit used for moving air at low pressures.
duct velocity: Air velocity through the duct cross section.
dusts: Solid particles generated by handling, crushing, grinding, rapid impact, detonation, and
decrepitation of organic or inorganic materials,such as rock ore,metal,coal,wood and grain.
Dusts do not tend to flocculate,except under electrostatic forces; they do not diffuse in air but
settle under the influence of gravity.
dyspnea: Shortness of breath, difficult or labored breathing.
electrical grounding: Precautionary measures designed into an electrical installation to eliminate
dangerous voltages in and around the installation, and to operate protective devices in case of
current leakage from energized conductors to their enclosures.
emergency plan: See contingency plan.
emergency response: The response made by firefighters,police,health care personnel,and/or
other emergency service upon notification of a fire, chemical spill, explosion, or other incident
in which human life and/or property may be in jeopardy.
energized (“live”): The conductors of an electrical circuit.Having voltage applied to such
conductors and to surfaces that a person might touch; having voltage between such surfaces and
other surfaces that might complete a circuit and allow current to flow.
energy: The capacity for doing work. Potential energy (PE) is energy deriving from position; thus
a stretched spring has elastic PE, and an object raised to a height above the Earth’s surface, or
the water in an elevated reservoir has gravitational PE.A lump of coal and a tank of oil, together
with oxygen needed for their combustion, have chemical energy. Other sorts of energy include
electrical and nuclear energy, light, and sound. Moving bodies possess kinetic energy (KE).
Energy can be converted from one form to another, but the total quantity stays the same (in
accordance with the conservation of energy principle). For example, as an orange falls, it loses
gravitational PE,but gains KE.
engineering: The application of scientific principles to the design and construction of structures,
machines,apparatus,manufacturing processes,and power generation and utilization,for the
purpose of satisfying human needs.Industrial hygiene is concerned with control of
environment and humankind’s interface with it,especially safety interaction with machines,
hazardous materials,and radiation.
engineering controls: Methods of controlling employee exposures by modifying the source or
reducing the quantity of contaminants released into the workplace environment.
Epidemiological Theory: Holds that the models used for studying and determining
epidemiological relationships can also be used to study causal relationships between
environmental factors and accidents or diseases.
ergonomics: A multidisciplinary activity dealing with interactions between man and his total
working environment, plus stresses related to such environmental elements as atmosphere, heat,
light,and sound,as well as all tools and equipment of the workplace.
etiology: The study or knowledge of the causes of disease.
evaporation: The process by which a liquid is changed into the vapor state.
evaporation rate: The ratio of the time required to evaporate a measured volume of a liquid
to the time required to evaporate the same volume of a reference liquid (butyl acetate, ethyl ether) under ideal test conditions.The higher the ratio,the slower the evaporation rate.The evaporation rate can be useful in evaluating the health and fire hazards of a material.
exhaust ventilation:A mechanical device used to remove air from any space.
exposure: Contact with a chemical,biological,or physical hazard.
exposure ceiling: Refers to the concentration level of a given substance that should not be
exceeded at any point during an exposure period.
face velocity: Average air velocity into an exhaust system measured at the opening of the hood or
booth.
fall arresting system: A system consisting of a body harness,a lanyard or lifeline,and an arresting
mechanism with built-in shock absorber, designed for use by workers performing tasks in
locations from which falls would be injurious or fatal, or where other kinds of protection are
not practical.
Federal Register: Publication of U.S. government documents officially promulgated under the
law,documents whose validity depends upon such publication.It is published on each day
following a government working day. It is, in effect, the daily supplement to the Code of Federal
Regulations (CFR).
fiber: Particle with an aspect ratio greater than 3:1 (NIOSH 5:1).
fire:A chemical reaction between oxygen and a combustible fuel.
fire point: The lowest temperature at which a material can evolve vapors fast enough to support
continuous combustion.
flame ionization detector: A direct reading instrument that ionizes gases and vapors with an
oxyhydrogen flame and measures the differing electrical currents thus generated.
flammable liquid:Any liquid having a flash point below 37.8°C (100°F),except any mixture
having components with flashpoints of 100°F or higher, the total of which make up 99% or
more of the total volume of the mixture.
flammable range: The difference between the lower and upper flammable limits,expressed in
terms of percentage of vapor or gas in air by volume, and is also often referred to as the
“explosive range.”
flammable solid: A nonexplosive solid liable to cause fire through friction,absorption of
moisture,spontaneous chemical change,or heat retained from a manufacturing process,or that
can be ignited readily and when ignited,burns so vigorously and persistently as to create a serious hazard.
flash point: The lowest temperature at which a liquid gives off enough vapor to form ignitable
moisture with air, and produce a flame when a source of ignition is present. Two tests are
used—open cup and closed cup.
foot-candle: A unit of illumination. The illumination at a point on a surface which is one foot
from, and perpendicular to, a uniform point source of one candle.
fume: Airborne particulate matter formed by the evaporation of solid materials,e.g.,metal fume
emitted during welding.Usually less than one micron in diameter.
gage pressure: Pressure measured with respect to atmospheric pressure.
gamma rays: High energy x-rays.
gas: A state of matter in which the material has very low density and viscosity,can expand and
contract greatly in response to changes in temperature and pressure, easily diffuses into other
gases, and readily and uniformly distributes itself throughout any container. Examples include
sulfur dioxide, ozone, and carbon monoxide.
gas chromatography: A detection technique that separates a gaseous mixture by passing it
through a column,enabling the components to be released at various times depending on their
molecular structure.Used as an analytical tool for air sampling gases and vapors.
Geiger-Muller counter:A gas-filled electrical instrument that indicates the presence of an atomic
particle or ray by detecting the ions produced.
general ventilation: A ventilation system using natural or mechanically generated make-up air to
mix and dilute contaminants in the workplace.
globe thermometer:A thermometer set in the center of a black metal sphere to measure radiant heat.
grab sample: A sample taken within a short duration to quantify or identify air contaminants.
gram (g): A metric unit of weight.One ounce equals 28.4 grams.
grounded system: A system of conductors in which at least one conductor or point is inten-
tionally grounded, either solidly or through a current-limiting (current transformer) device.
ground-fault circuit interrupter (GFCI): A sensitive device intended for shock protection, which
functions to de-energize an electrical circuit or portion thereof within a fraction of a second,in
case of leakage to ground of current sufficient to be dangerous to persons but less than that
required to operate the overcurrent protective device of the circuit.
half-life: For a single radioactive decay process, the time required for the activity to decrease to
half its value by that process.
hazard: The potential for an activity,condition,circumstance,or changing conditions or
circumstances to produce harmful effects.Also an unsafe condition.
hazard analysis:A systematic process for identifying hazards and recommending corrective action.
Hazard and Operability (HAZOP) Analysis: A systematic method in which process hazards and
potential operating problems are identified,using a series of guide words to investigate process
deviations.
hazard assessment:A qualitative evaluation of potential hazards in the interrelationships between
and among the elements of a system,upon the basis of which the occurrence probability of each
identified hazard is rated.
Hazard Communication Standard (HazCom):An OSHA workplace standard found in 29
CFR1910.1200 (OSHA,1995) that requires all employers to become aware of the chemical
hazards in their workplace and relay that information to their employees.In addition,a
contractor conducting work at a client’s site must provide chemical information to the client
regarding the chemicals that are brought onto the work site.
hazard control: A means of reducing the risk from exposure to a hazard.
hazard identification: The pinpointing of material,system,process,and plant characteristics that
can produce undesirable consequences through the occurrence of an accident.
hazardous material: Any material possessing a relatively high potential for harmful effects upon
persons.
hazardous substance: Any substance which has the potential for causing injury by reason of its
being explosive,flammable,toxic,corrosive,oxidizing,irritating,or otherwise harmful to personnel.
hazardous waste: A solid,liquid,or gaseous waste that may cause or significantly contribute to
serious illness or death,or that poses a substantial threat to human health or the environment
when the waste is improperly managed.When a hazardous material is spilled,it becomes a hazardous waste.
hearing conservation: The prevention of, or minimizing of noise-induced deafness through the
use of hearing protection devices, the control of noise through engineering controls, annual
audiometric tests and employee training.
heat cramps: A type of heat stress resulting in muscle spasms.Exposure to excessive heat results in
salt and potassium depletion.
heat exhaustion: A condition usually caused by loss of body water from exposure to excessive
heat.Symptoms include headache,tiredness,nausea,and sometimes fainting.
heat rash: A rash caused by sweating and inadequate hygiene practices.
heat stroke: A serious disorder resulting from exposure to excessive heat. Caused by sweat
suppression and increased storage of body heat. Symptoms include hot, dry skin, high
temperature,mental confusion,collapse,and sometimes convulsions or coma.
HEPA (High Efficiency Particulate Air) filter: A disposable, extended medium, dry type filter
with a particle removal efficiency of no less than 99.97% for 0.3m particles.
Homeland Security: Federal cabinet level department created to protect America as a result of
9/11.The new Department of Homeland Security (DHS) has three primary missions: prevent
terrorist attacks within the United States, reduce America’s vulnerability to terrorism, and
minimize the damage from potential attacks and natural disasters.
hood entry loss: The pressure loss from turbulence and friction as air enters a ventilation system.
hot work:Work involving electric or gas welding,cutting,brazing,or similar flame or spark-producing
operations.
human factor engineering (used in the United States) or ergonomics (used in Europe): For
practical purposes,the terms are synonymous,and focus on human beings and their interaction
with products,equipment,facilities,procedures,and environments used in work and everyday
living. The emphasis is on human beings (as opposed to engineering, where the emphasis is
more strictly on technical engineering considerations) and how the design of things influences
people.Human factors,then,seek to change the things people use and the environments in
which they use these things to better match the capabilities, limitations, and needs of people
(Sanders & McCormick, 1993).
IDLH: Immediately Dangerous to Life and Health.An atmospheric concentration of any toxic,
corrosive,or asphyxiant substance that poses an immediate threat to life,would cause
irreversible or delayed adverse health effects, or would interfere with an individual’s ability to
escape from a dangerous atmosphere.
ignition source: Anything that provides heat, spark, or flame sufficient to cause combustion or an
explosion.
ignition temperature: The temperature at which a given fuel can burst into flame.
illumination: The amount of light flux a surface receives per unit area.May be expressed in
lumens per square foot or in foot-candles.
impaction: Forcibly lodging particles into matter.
impervious:A material that does not allow another substance to pass through or penetrate it.
Frequently used to describe gloves or chemical protective clothing.
impingement: The process of collecting particles by pulling contaminated air through a device
filled with water or reagent (particles remain in the liquid).
impulse noise:A noise characterized by rapid rise time,high peak value,and rapid decay.
inches of mercury column: A unit used in measuring pressures. One inch of mercury column
equals a pressure of 1.66 kPa (0.491 psi).
inches of water column.A unit used in measuring pressures. One inch of water column equals a
pressure of 0.25 kPa (0.036 psi).
incident: An undesired event that, under slightly different circumstances, could have resulted in
personal harm or property damage; any undesired loss of resources.
incompatible:Materials that could cause dangerous reactions from direct contact with one another.
Indoor Air Quality (IAQ): Refers to the effect, good or bad, of the contents of the air inside a
structure, on its occupants. Usually, temperature (too hot and cold), humidity (too dry or too
damp),and air velocity (draftiness or motionless) are considered “comfort”rather than IAQ
issues.Unless those are extreme,they may make someone unhappy,but they won’t make a
person ill. Nevertheless, most IAQ professionals will take these factors into account in
investigating air quality situations.
industrial hygiene: The American Industrial Hygiene Association (AIHA) defines industrial
hygiene as “that science and art devoted to the anticipation,recognition,evaluation,and control
of those environmental factors or stresses—arising in the workplace—which may cause
sickness,impaired health and well-being,or significant discomfort and inefficiency among
workers or among citizens of the community.”
ingestion: Taking in by the mouth.
inhalation: Breathing of a substance in the form of a gas, vapor, fume, mist, or dust.
injury:A wound or other specific damage.
insoluble: Incapable of being dissolved in a liquid.
interlock: A device that interacts with another device or mechanism to govern succeeding
operations. For example, an interlock on an elevator door prevents the car from moving unless
the door is properly closed.
ionizing radiation: Radiation that becomes electrically charged or changed into ions.
irritant: A substance that produces an irritating effect when it contacts skin,eyes,nose,or
respiratory system.
job hazard analysis: The breaking down into its component parts of any method or procedure, to
determine the hazards connected therewith and the requirements for performing it safely.Also
called job safety analysis.
Kelvin: A temperature scale,also called absolute temperature,where the temperature is measured
on the average kinetic energy per molecule of a perfect gas.
kinetic energy: The energy resulting from a moving object.
Laboratory Safety Standard: A specific hazard communication program for laboratories,found in
29 CFR 1910.1450 (OHSA,1995).These regulations are essentially a blend of hazard
communication and emergency response for laboratories. The cornerstone of the Lab Safety
Standard is the requirement for a written Chemical Hygiene Plan.
laser: Light amplification by stimulated emission of radiation.
latent period: The time that elapses between exposure and the first manifestation of damage.
LC 50 : Lethal concentration that will kill 50% of the test animals within a specified time.
LD 50 : The dose required to produce death in 50% of the exposed species within a specified time.
Liter (L): A measure of capacity. One quart equals 0.9L.
local exhaust ventilation:A ventilation system that captures and removes contaminants at the
point of generation before escaping into the workplace.
Lockout/Tagout Procedure: An OSHA procedure found in 29 CFR 1910.147 (OHSA,1995).A tag
or lock is used to tag out or lock out a device, so that no one can inadvertently actuate the
circuit, system, or equipment that is temporarily out of service.
Log and Summary of Occupational Injuries and Illnesses (OSHA-200 Log): A cumulative record
that employers (generally of more than 10 employees) are required to maintain, showing
essential facts of all reportable occupational injuries and illnesses.
loss: The degradation of a system or component.Loss is best understood when related to dollars lost.
Examples include death or injury to a worker,destruction or impairment of facilities or machines,
destruction or spoiling of raw materials,and creation of delay.In the insurance business,loss
connotes dollar loss,and we have seen underwriters who write it as LO$$ to make that point.
lower explosive limit (LEL): The minimum concentration of a flammable gas in air required for
ignition in the presence of an ignition source. Listed as a percent by volume in air.
makeup air: Clean,tempered outdoor air supplied to a workplace to replace air removed by
exhaust ventilation.
malignant: As applied to a tumor. Cancerous and capable of undergoing metastasis, or invasion of
surrounding tissue.
Material Safety Data Sheet (MSDS): Chemical information sheet provided by the chemical
manufacturer that includes information such as chemical and physical characteristics; long and
short term health hazards; spill control procedures; personal protective equipment (PPE) to be
used when handling the chemical; reactivity with other chemicals; incompatibility with other
chemicals; and manufacturer’s name,address,and phone number.Employee access to and
understanding of MSDS are important parts of the HazCom Program.
medical monitoring: The initial medical exam of a worker, followed by periodic exams. The
purpose of medical monitoring is to assess workers’health,determine their fitness to wear
personal protective equipment,and maintain records of their health.
mesothelioma: Cancer of the membranes that line the chest and abdomen, almost exclusively
associated with asbestos exposure.
metabolic heat: Produced within a body as a result of activity that burns energy.
metastasis: Transfer of the causal agent (cell or microorganisms) of a disease from a primary
focus to a distant one through the blood or lymphatic vessels.Also, spread of malignancy from
site of primary cancer to secondary sites.
meter: A metric unit of length,equal to about 39 inches.
micron (micrometer,m): A unit of length equal to one millionth of a meter, approximately
1/25,000 of an inch.
milligram (mg): A unit of weight in the metric system.One thousand milligrams equals one gram.
milligrams per cubic meter (mg/m3): Unit used to measure air concentrations of dusts,gases,
mists,and fumes.
milliliter (mL):A metric unit used to measure volume.One milliliter equals one cubic centimeter.
millimeter of mercury (mmHg): The unit of pressure equal to the pressure exerted by a column
of liquid mercury one millimeter high at a standard temperature.
mist: Tiny liquid droplets suspended in air.
molds: The most typical form of fungus found on earth, comprising approximately 25% of the
earth’s biomass (McNeel and Kreutzer, 1996).
monitoring: Periodic or continuous surveillance or testing to determine the level of compliance
with statutory requirements and/or pollutant levels, in various media or in humans, animals, or
other living things.
mucous membranes: Lining of the hollow organs of the body,notably the nose,mouth,stomach,
intestines,bronchial tubes,and urinary tract.
mutagen: A substance or material that causes change in the genetic material of a cell.
mycotoxins: Some molds are capable of producing mycotoxins,natural organic compounds that
are capable of initiating a toxic response in vertebrates (McNeel and Kreutzer,1996).
NFPA: National Fire Protection Association.A voluntary membership organization whose aim is
to promote and improve fire protection and prevention. The NFPA publishes 16 volumes of
codes known as the National Fire Codes.
NIOSH: The National Institute for Occupational Safety and Health.A federal agency that
conducts research on health and safety concerns,tests and certifies respirators,and trains
occupational health and safety professionals.
non-ionizing radiation: That radiation on the electromagnet spectrum that has a frequency of
10 15 or less and a wavelength in meters of 3 × 10 –7 .
NTP: National Toxicology Program.The NTP publishes an annual report on carcinogens.
nuisance dust: Has a long history of little adverse effect on the lungs and does not produce
significant organic disease or toxic effect when exposures are kept under reasonable control.
Occupational Safety and Health Act (OSH Act): A federal law passed in 1970 to assure,so far as
possible,every working man and woman in the nation safe and healthful working conditions.
To achieve this goal,the Act authorizes several functions,such as encouraging safety and health
programs in the workplace and encouraging labor-management cooperation in health and
safety issues.
OSHA Form 300: Log and Summary of Occupational Injuries and Illnesses.
oxidation: When a substance either gains oxygen,or loses hydrogen or electrons in a chemical
reaction.One of the chemical treatment methods.
oxidizer: Also known as an oxidizing agent, a substance that oxidizes another substance. Oxidizers
are a category of hazardous materials that may assist in the production of fire by readily yielding
oxygen.
oxygen deficient atmosphere: The legal definition of an atmosphere where the oxygen
concentration is less than 19.5% by volume of air.
oxygen-enriched atmosphere: An atmosphere containing more than 23.5% oxygen by volume.
particulate matter: Substances (such as diesel soot and combustion products resulting from the
burning of wood) released directly into the air; any minute,separate particle of liquid or solid
material.
performance standards: A form of OSHA regulation standards that lists the ultimate goal of
compliance, but does not explain exactly how compliance is to be accomplished. Compliance is
usually based on accomplishing the act or process in the safest manner possible,based on
experience (past performance).
permissible exposure limit (PEL): The time-weighted average concentration of an airborne
contaminant that a healthy worker may be exposed to 8 hours per day or 40 hours per week
without suffering any adverse health effects.Established by legal means and enforceable by OSHA.
personal protective equipment (PPE): Any material or device worn to protect a worker from
exposure to or contact with any harmful substance or force.
pH: Means used to express the degree of acidity or alkalinity of a solution with neutrality
indicated as seven.
pitot tube: A device used for measuring static pressure within ventilation ducts.
polymerization:A chemical reaction in which two or more small molecules (monomers)
combine to form larger molecules (polymers) that contain repeating structural units of the
original molecules.A hazardous polymerization is the above reaction,with an uncontrolled
release of energy.
ppm: Parts per million parts of air by volume of vapor or gas or other contaminant.Used to
measure air concentrations of vapors and gases.
precision: The degree of exactness of repeated measurements.
preliminary assessment: A quick analysis to determine how serious the situation is, and to
identify all potentially responsible parties.The preliminary assessment uses readily available
information, such as forms, records, aerial photographs, and personnel interviews.
pressure: The force exerted against an opposing fluid or thrust distributed over a surface.
psi: Pounds per square inch. For MSDS purposes, the pressure a material exerts on the walls of a
confining vessel or enclosure.For technical accuracy,pressure must be expressed as psig
(pounds per square inch gauge) or psia (pounds per square absolute; that is, gauge pressure plus
sea level atmospheric pressure, or psig plus approximately 14.7 pounds per square inch).
radiant heat: The result of electromagnetic nonionizing energy that is transmitted through space
without the movement of matter within that space.
radiation: Consists of energetic nuclear particles and includes alpha rays, beta rays, gamma rays,
x-rays, neutrons, high-speed electrons, and high-speed protons.
Raynaud’s syndrome: Caused by vibrating hand tools,an abnormal constriction of blood vessels
in the fingers when exposed to cold temperature.
RCRA: Resource Conservation and Recovery Act of 1976.
reactivity (chemical): A substance that reacts violently by catching on fire,exploding,or giving off
fumes when exposed to water, air, or low heat.
reactivity hazard: The ability of a material to release energy when in contact with water.Also,the
tendency of a material, when in its pure state or as a commercially produced product, to
vigorously polymerize, decompose, condense, or otherwise self-react and undergo violent chemical change.
reportable quantity (RQ): The minimum amount of a hazardous material that,if spilled while in
transport,must be reported immediately to the National Response Center.Minimum
reportable quantities range from 1 pound to 5,000 pounds per 24-hour day.
respirable size particulates: Particulates in the size range that permits them to penetrate deep into
the lungs upon inhalation.
respirator (approved): A device which has met the requirements of National Institute of Safety
and Health (NIOSH) 42 CFR Part 84 and is designed to protect the wearer for 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 system: Consists of (in descending order)—the nose, mouth, nasal passages, nasal
pharynx, pharynx, larynx, trachea, bronchi, bronchioles, air sacs (alveoli) of the lungs, and
muscles of respiration.
risk: The combination of the expected frequency (event/year) and consequence (effects/event) of
a single accident or a group of accidents; the result of a loss-probability occurrence and the
acceptability of that loss.
risk assessment: A process that uses scientific principles to determine the level of risk that actually
exists in a contaminated area.
risk characterization: The final step in the risk assessment process,it involves determining
a numerical risk factor.This step ensures that exposed populations are not at significant
risk.
risk management: The professional assessment of all loss potentials in an organization’s structure
and operations, leading to the establishment and administration of a comprehensive loss
control program.
rotameters: A small tapered tube with a solid ball (float) inside used to measure flow rate of air
sampling equipment.
safety: A general term denoting an acceptable level of risk of, relative freedom from, and low
probability of harm.
safety factor: Based on experimental data,the amount added (e.g.,1000-fold) to ensure worker
health and safety.
safety standard: A set of criteria specifically designed to define a safe product,practice,
mechanism, arrangement, process, or environment, produced by a body representative of all
concerned interests,and based upon currently available scientific and empirical knowledge
concerning the subject or scope of the standard.
SARA: Superfund Amendments and Reauthorization Act of 1986.
SCBA: Self-contained breathing apparatus.
secondary containment: A method using two containment systems so that if the first is breached,
the second will contain all of the fluid in the first.For underground storage tanks (USTs),
secondary containment consists of either a double-walled tank or a liner system.
security assessment: An intensified security test in scope and effort,the purpose of which is to
obtain an advanced and very accurate idea of how well the organization has implemented
security mechanisms and, to some degree, policy.
sensitizers: Chemicals that in very low dose trigger an allergic response.
short term exposure limit (STEL): The time weighted average concentration to which workers
can be exposed continuously for a short period of time (typically 15 minutes) without suffering
irritation,chronic or irreversible tissue damage,or impairment for self-rescue.
silica: Crystalline silica (SiO 2 ) is a major component of the earth’s crust and is responsible for
causing silicosis.
“skin”: A notation (sometimes used with PEL or TLV exposure data) which indicates that the
stated substance may be absorbed by the skin,mucous membranes,and eyes—either airborne
or by direct contact—and that this additional exposure must be considered part of the total
exposure to avoid exceeding the PEL or TLV for that substance.
solubility in water: A term expressing the percentage of a material (by weight) that will dissolve in
water at ambient temperature. Solubility information can be useful in determining spill cleanup
methods and re-extinguishing agents and methods for a material.
solvent: A substance,usually a liquid,in which other substances are dissolved.The most common
solvent is water.
sorbent: (1) A material that removes toxic gases and vapors from air inhaled through a canister or
cartridge. (2) Material used to collect gases and vapors during air-sampling.
specific gravity: The ratio of the densities of a substance to water.
stability: An expression of the ability of a material to remain unchanged. For MSDS purposes, a
material is stable if it remains in the same form under expected and reasonable conditions of
storage or use. Conditions which may cause instability (dangerous change) are stated, for
example, temperatures above 150°F or shock from dropping.
synergism: Cooperative action of substances whose total effect is greater than the sum of their
separate effects.
systemic: Spread throughout the body, affecting all body systems and organs,rather than localized
in one spot or area.
temporary threshold shift (TTS): Temporary hearing loss due to noise exposure.May be partially
or completely recovered when exposure ends.
tendonitis: Inflammation of a tendon.
tenosynovitis: Inflammation of the connective tissue sheath of a tendon.
threshold: The lowest dose or exposure to a chemical at which a specific effect is observed.
threshold limit value (TLV): The same concept as PEL except that TLVs do not have the force of
governmental regulations behind them, but are based on recommended limits established and
promoted by the American Conference of Governmental Industrial Hygienists.
time-weighted average (TWA): A mathematical average of exposure concentration over a specific time.
total quality management (TQM): A way of managing a company that revolves around a total
and willing commitment of all personnel at all levels to quality.
toxicity: The relative property of a chemical agent with reference to a harmful effect on some
biologic mechanism and the condition under which this effect occurs.In other words,the quality
of being poisonous.
toxicology: The study of poisons,which are substances that can cause harmful effects to living things.
toxin: A poison.
unsafe condition: Any physical state that deviates from that which is acceptable, normal, or
correct in terms of past production or potential future production of personal injury and/or
damage to property; thus, any physical state that results in a reduction in the degree of safety
normally present.
upper explosive limit (UEL): The maximum concentration of a flammable gas in air required for
ignition in the presence of an ignition source.
vapor: The gaseous form of substances that are normally solid or liquid at room temperature.
vapor pressure: Pressure—measured in pounds per square inch absolute (psia)—exerted by a
vapor.If a vapor is kept in confinement over its liquid so that the vapor can accumulate above
the liquid (the temperature being held constant),the vapor pressure approaches a fixed limit
called the maximum (or saturated) vapor pressure, dependent only on the temperature and the
liquid.
vapors: The gaseous form of substances that are normally in the solid or liquid state (at room
temperature and pressure).The vapor can be changed back to the solid or liquid state either by
increasing the pressure or decreasing the temperature alone.Vapors also diffuse. Evaporation is
the process by which a liquid is changed into the vapor state and mixed with the surrounding
air.Solvents with low boiling points will volatize readily.Examples include benzene,methyl
alcohol, mercury, and toluene.
velometer:A device used in ventilation to measure air velocity.
viscosity: The property of a fluid that resists internal flow by releasing counteracting
forces.
volatility: The tendency or ability of a liquid to vaporize. Liquids such as alcohol and gasoline,
because of their well-known tendency to evaporate rapidly,are called volatile liquids.
vulnerability assessment: A very regulated, controlled, cooperative, and documented evaluation
of an organization’s security posture from outside-in and inside-out, for the purpose of
defining or greatly enhancing security policy.
water column: A unit used in measuring pressure.
wet bulb globe temperature: Temperature as determined by the wet bulb thermometer
(a bulb covered with a cloth saturated with water) or a standard sling psychrometer or its
equivalent. Influenced by the evaporation rate of water which,in turn,depends on relative
air humidity.
workers’compensation: A system of insurance required by state law and financed by employers,
which provides payments to employees and their families for occupational illnesses, injuries, or
fatalities incurred while at work and resulting in loss of wage income,usually regardless of the
employer’s or employee’s negligence.

zero energy state: The state of equipment in which every power source that can produce
movement of a part of the equipment, or the release of energy, has been rendered inactive.
zoonoses: Diseases communicable from animals to humans under natural conditions.

Please comment Your Valuable Suggestions ...