Safe A condition or situation that is resonably free from hazards that may cause injury or adverse health effets
Safe day A workday in whihc there were no lost time injuries.
safety The proper handling of a substance or carrying out of a task to eliminate its capacity to cause injury or do harm.
safety belt Device worn around the waist or as a harness for securing a person to a structure or within a vehicle.
safety can An approved container of not more than 5 gallons capacity, having a spring-closing lid and spout cover, and so designed that it will safely relieve pressure when subjected to fire exposure.
safety engineering Discipline concerned with the planning, development, implementation, maintenance, and evaluation of the safety aspects of equipment, the environment, procedures, operations, and systems to achieve effective protection of people and property.
safety factor The ratio of the normal working condition to the ultimate condition.
safety guard (Grinder) Enclosure for containing pieces of the grinding wheel in the event the wheel is broken during use.
safety professional An individual with specialized skills, knowledge, and/or education who has achieved professional status in die safety profession.
safety relief valve A valve fitted on a pressure vessel or other containment under pressure to relieve overpressure.
safety valve A pressure relief valve that is actuated by inlet pressure and with resultant rapid opening above its pressure setting.
salamander Portable type of furnace without grates that is used as a space heater in some work locations.
salinity The degree of salt in the water. saliva The clear, alkaline secretions from the mucous glands of the mouth.
salivation The excessive excretion of saliva.
sample (Industrial Hygiene) An airborne contaminant (fume, dust mist, vapor, etc.) collected from the air within the workplace, or die measurement of the level of a physical agent (noise, heat, ionizing radiation, etc.) to which workers are exposed. The sample must be random and representative of the exposure of the individual sampled, as well as collected in an acceptable manner so that it can be compared to an established exposure standard.
sample (Statistics) The part or subset of a population that is selected for statistical analysis.
sample blank The gross instrument response attributable to reagents, solvents, and the sample media used in air sampling and subsequent analysis of samples. See blank.
sample draw (Sampling) The procedure and method used to cause the deliberate flow of the atmosphere being monitored to a sensing element. See active sampling.
sample parameters Estimators of population parameters, such as the mean, standard deviation, etc.. based on observations of a subset of the population.
sample storage stability The period of time, in days, over which storage losses of analytes are generally less than 10 percent, provided that storage and shipment precautions are observed. It is determined by collecting a number of samples at the level of concern (e.g., the TLV) at room temperature and about 80 percent relative humidity, and subsequently analyzing sets of these samples (e.g., about 6 in each set) over a 2-week or longer period to determine losses that may occur during storage.
Saturated air Air containing saturateed water vapor with both the air and water vapor at the same dey-bulb temperature.
saturated steam Steam at the boiling temperature corresponding to the pressure at which it exists.
secondary air Combustion air that is supplied over the firebed to oxidize the volatile constituents of the fuel, as distinguished from primary air that is introduced below the firebed.
secondary calibration method Method that employs a device that must be calibrated against a primary standard method; not as accurate as a primary method. A wet-test meter, dry-gas meter, and a rotometer are examples of secondary standard methods that must be calibrated against a primary standard (see secondary standard).
secondary carcinogen A carcinogen that needs metabolic activation; that is, one that is converted to a carcinogen by cell metabolism.
secondary combustion air The air introduced above or below a fuel by natural, induced, or forced draft.
secondary infection An infection acquired from person-to-person transfer from a primary case or from other secondary cases.
secondary pollutant A pollutant formed in the atmosphere by chemical changes taking place between primary pollutants and other substances present in the air.
secondary radiation Ionizing radiation originating as a result of the absorption of other radiation in matter.
secondary standard (Air Pollution) An air pollution standard that establishes an ambient concentration of a pollutant with a margin of safety [hat will protect the environment from adverse effect
secondary standard (Flow Rate) Air flow measuring device that traces its calibration to a primary standard and that must be periodically recalibrated (see secondary calibration method).
secondary treatment (Wastcwater) Process and operation for converting dissolved organ-ics to biological solids and removing those solids from the wastewaler stream,
second-hand smoke Tobacco smoke in the air that is inhaled by nonsmokers.
secular equilibrium (Ionizing Radiation) The condition that exists when the ratio of parent nuclei to daughter nuclei remains constant with time. Thus, both parent and daughter decay at the same rate (i.e., that of the parent).
Sedgwick rafter cell A glass slide/cell, formerly used to contain an aliquot of the collection media in which airborne paniculate was collected. The cell was used to count the par-ticulates microscopically so that a determination of dust concentration could be made.
sediment Paniculate matter that has been deposited in an area or has settled out of water or other liquid, e.g., urine.
sedimentation The process by which solids settle out of a fluid (e.g., air or water)
sedimentation rate Test that measures the rate at which blood cells (e.g., erythrocytes) settle out of a sample of drawn blood. r artificially produced earth nstalled and must be refilled
segregation (Public Health) The separation for special consideration, control, or observation, of some part of a group of persons or of domestic animals from others, to facilitate the control of communicable diseases.
seismic data Detailed information obtained from naturally vibration. self-contained eyewash An eyewash that is not permanently or replaced after use.
self contained respirator One of three types of respiratory protective devices that is designed to provide breathing air to the wearer, independent of the surrounding atmosphere: open-circuit system, closed-circuit system with oxygen self-generating capability, and compressed air or oxygen closed-circuit device. Also classified as demand and pressure-demand units,
self-contained breathing apparatus [SCBA] See self-contained respirator.
self-insured The assumption of liability for worker compensation by a company to avoid
SEM Scanning electron microscope.
semantics The study of the meaning or significance of words in a language.
senility The state of being senile (old).
sensation The awareness of the effects of a stimulus exciting one of the organs of the senses.
sense organ A body organ that is sensitive to a specific stimulus, such as sight, hearing, smell, taste, and touch.
sensible Capable of being perceived by one of the sense organs.
sensible heat Heat that, when added or removed, results in a change of temperature.
sensitive Capable of perceiving and responding to external stimuli or conditions.
sensitivity (Instrument) The minimum amount of contaminant that can be repeatedly detected by the device, and the minimum input signal strength required to produce a desired value of output signal.
sensitivity (Physiology) The ability of an organism to respond to stimuli.
sensitization The process of rendering an individual sensitive to the action of a chemical. Involves an initial exposure of the individual to a specific antigen, resulting in an immune response. A subsequent exposure then induces a much stronger immune response.
sensor (Instrument) A transducer which converts a parameter at a sample point to a form suitable for measurement.
sensorinenral hearing loss Type of bearing loss typically caused by exposure to noise. This type hearing loss affects numerous people and is the result of damage to the inner ear, along with damage to the fibers of the acoustic nerve.
sensory response The activity of the sense organs on stimulation that results in discomfort, but with no lasting or systemic injury.
senstizer A foreign agent or substance that is capable of causing a state of abnormal responsiveness in an individual. Following repealed or extended exposure to a substance, some people develop an allergic type of skin irritation referred to as sensitization dermatitis, while others may have a more serious response.
sepsis Infection of a wound or body tissues with bacteria, which leads to the formation of pus or to the multiplication of the bacteria in the blood.
septic material Material that can cause sepsis, which is the presence of pathogenic organisms or their toxins in the blood or tissues.
septic tank An enclosure for the storage and processing of wastes where no sewer system exists. Bacteria decompose the organic matter into sludge, which must be pumped out periodically.
septkemia Blood poisoning, with actual growth of infectious organisms in the blood.
sequela Condition, lesion, or any affection following or resulting from a disease. A pathological condition resulting from a disease.
serendipity The accidental discovery of important new information.
serious bodily injury (OSHA) An injury that involves a substantial risk of death, protracted unconsciousness, protracted and obvious physical disfigurement, or protracted loss or impairment of die function of a bodily member, organ, or mental facility.
serious hazard (OSHA) Any condition or practice that could be classified as a serious violation of applicable federal or state statutes, regulations, or standards, based on criteria contained in the current Field Operations Manual or an approved stale counterpart, except that the element of employer knowledge shall not be considered.
serious violation (OSHA) Violation in which there is a substantial probability that death or serious physical harm could result from a condition that exists, and that the employer knew or should have known of the hazard.
serious violation citation (OSHA) A citation that is issued when there is a substantial probability that death or serious physical harm could result from a condition that exists and the employer knows about or, with the exercise of reasonable diligence, could have known about
serology The branch of medicine concerned with the analysis of blood serum
seropositive The presence in the blood of antibodies to a disease-causing agent
serpentine One of the two major groups of minerals from which the asbestiform minerals are derived.
service life (Air-Purifying Respirator) The period of time that a respirator, filter, or sor-bent or other respiratory equipment provides adequate protection to the wearer
settling chamber A large chamber or expansion in an exhaust system in which the air velocity slows down to a rale at which larger particles suspended in the air settle out.
settling velocity The velocity at which particles of specific sizes will settle out of the atmosphere due to the effect of gravity. Also referred to as the terminal velocity.
severity rate (Disabling Injury) Relates the days charged to an accident with the hours worked during the period and expresses the result in terms of a million-hour unit.
sewage Human body wastes and the wastes from toilets and other receptacles intended to receive or retain body wastes.
Shaver's disease A pneumoconiosis resulting from inhalation of fumes emitted from electric furnaces in the production of corundum.
shield (Ionizing Radiation) A material used to prevent or reduce the passage of ionizing radiation. Shielding is used to reduce the exposures of workers and patients to radiation emitted from sources.
short ton Equal to 2000 pounds or 907 kilograms.
short-term delayed effect A health effect that occurs within a week to a month or so following a first exposure to a toxicant.
short-term exposure limit [STEL] A 15-minute, time-weighted average exposure to a substance that should not be exceeded at any time during a workday, even if the 8-hour exposure is within the TLV-TWA. Exposures up to the STEL value should not be for longer than I5 minutes, nor occur more than 4 times per day, and there should be at least 60 minutes between successive exposures in this range.
shot blasting A method for cleaning surfaces employing steel shot in a nigh-pressure air stream. A generic term for the cleaning of surfaces using abrasive cleaning agents.
SI Systeme International, Internationa] System of Units.
SI Units Systeme International d'Units.
siblings Children borne by the same mother.
SIC Standard Industrial Classification.
sick building syndrome [SBS] Situation in which building occupants experience acute health and/or discomfort effects that appear to be linked to time spent in the building, but in which no specific illness or cause can be identified.
side effect An effect other than the intended one.
skewed A property of a statistical distribution indicating a lack of symmetry around the mean, such that the observations are concentrated to the left or right of the mean.
skewness The tendency of a distribution to depart from symmetry around the mean,
skin carcinogen A substance or physical agent that can produce skin cancer.
skin contamination The presence of a hazardous substance on the skin, presenting the potential for irritation, corrosive action, sensitization, skin absorption, etc.
skin disorder Any cutaneous abnormality or in the work environment.
skin dose The dose applied to the surface of the skin, or the dose received as a result of skin absorption.
skin injury An immediate adverse effect on the skin that results from instantaneous trauma or brief exposure to toxic agents involving a single incident in the work environment.
skin notation The reference on a TLV to the potential contribution to the overall exposure to the substance by absorption through the skin, mucous membranes, or the eye, upon contact with the material ot its vapor.
sling psycbrometer A device used to determine the properties of moist air by measuring the dry- and wet-bulb temperatures on thermometers fitted to a handle that enables their rapid rotation and the consequent evaporation of water from a wick placed over the bulb of the wet- bulb thermometer. The resulting temperatures (dry- and wet-bulb) are aligned on a psychometric chart to determine the properties of the air.
smog Irritating haze in the atmosphere as a result of the sun's effect on certain pollutants in the air, notably those from automobile and industrial exhaust emissions. Originally defined as a mixture of smoke and fog dispersed in the atmosphere.
smoke An aerosol (air suspension) of particles, usually solids, thai often originate or are formed by combustion or sublimation.
smoke detector A device that senses visible or invisible particles of combustion. smoke number A dimensionless number thai quantifies smoke emissions from a source.
smoke tube A glass tube containing a chemical adsorbed on a solid media and that emits a smoke-like cloud when air is blown through the tube,
smolder Bum with little smoke and no flame.
sound Pressure variations that travel through the air and are detected by the ear. The auditory sensation evoked by an oscillation in pressure, stress, particle displacement, particle velocity, etc. in a medium with internal forces (e.g., elastic or viscous).
sound absorption The change of sound energy into beat, in passing through a material or striking a surface.
sound analyzer A device for measuring the sound-pressure level as a function of frequency
sound exposure The cumulative acoustic stimulation at the ear of a person over a period of time,
sound field A region containing sound waves.
sound intensity The average rate at which sound energy is transmitted through a unit area, perpendicular to a specified point.
sound level Weighted sound-pressure level determined with a sound level meter having a standard frequency-filter for attenuating part of the sound spectrum.
sound level contours Lines drawn on a plot plan of a facility at positions of equal noise level.
sound level meter An instrument comprised of a microphone, amplifier, frequency-weighting networks, and output meter that can be used to measure sound-pressure levels in a manner specified by the manufacturer.
sound power level (Acoustics) [PWL] Ten times the log to the base 10 of the ratio of a given power to a reference power (i.e., IE"12 watts).
sound pressure level (Acoustics) [SPL] The level, in decibels, of a sound equal to 20 times the logarithm to the base 10 of the ratio of the pressure of the sound to a reference pressure. The reference pressure is 2 E ~4microbar, which is equivalent to 20 micronewtons per meter square.
sound shadow The acoustical equivalent of a light shadow.
sound transmission loss The ability of a barrier to block sound transmission as indicated by the reduction in decibels on the downstream side compared to that on the upstream side of the barrier material.
sound waves The longitudinal waves moving out from a noise si d to vibrate along the direction of the wave motion.
stability (Atmospheric) The tendency of the atmosphere to resist vertical motion, or alternately, to supress existing turbulence. It is related to both wind shear and temperature structure vertically, but the latter is generally used as an indicator of atmospheric stability.
stable air An air mass that slays in the same position rather than moving in its normal direction, thereby resulting in a buildup of air pollutants.
stable material Material that normally has the capacity to resist changes in its chemical composition, despite exposure to air, water, and heal as encountered in fire emergencies.
stack The device at the end of a ventilation system or furnace through which exhaust from the operation or ventilation system is released to the atmosphere.
stack effect Pressure-driven airflow produced by convection as heated air rises, creating a positive pressure in the top of a building and a negative pressure at the bottom. In houses and buildings it is die tendency toward the displacement of internal heated air by unheated outside air due to the difference in density of the outside and inside air.
stack sampling The collection of representative samples of gaseous or paniculate matter flowing through a stack or duct.
stagnation (Air Pollution) An atmospheric condition in which there is a lack of air movement, resulting in a buildup of air contaminants.
standard Something that serves as a basis for comparison.
standard air (Industrial Hygiene) Air at 25¢XC (T7"F) and 760 millimeters of mercury pressure.
standard air (Ventilation) Air at 70¢XF, 50 percent relative humidity, 29.92 inches of mercury atmospheric pressure, and weighing 0.075 pounds per cubic fool.
standard air density (Ventilation) The density of air at standard conditions is 0.075 pounds per cubic foot.
standard cubic foot A volume unit of measurement at a specified temperature and pressure. The temperature and/or pressure vary based on the discipline. For example, the specified temperature employed in industrial hygiene determinations is 25 ¢XC
standard deviation (Sample) A unidess number that indicates the scatter of data from the mean. A measure of the variability or dispersion of a set of results. The square root of the sample variance.
system A set or arrangement of components so related or connected as to form a unity or whole.
system safety A program oriented toward hardware and the functioning of systems, subsystems, and the components of the system and subsystems. systole Heart muscle contraction, especially that of the ventricles.
systematic errors Errors introduced by an individual, the result of a poor method/technique, improper reading/recording of data, or a consistent error in an instrument. These do not cancel out if more samples are collected and analyzed, and they always cause bias.
systematic Affecting the body and/or the organs that are remote from the site of exposure.
systematic effect A toxic effect that is remote from the point of contact or site at which the material entered the body. For example, vinyl chloride enters the body by inhalation, but affects the liver if a sufficient dose is absorbed by this route.