Z94.13 - Occupational Health & Safety

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ICD. International Classification of Diseases, Injuries, and Causes of Death.

IDLH (IMMEDIATELY DANGEROUS TO LIFE AND HEALTH). The air concentration of a substance at which exposure would result in death or serious injury to a person.

ILLUMINATION. The amount of light flux a surface receives per unit area. May be expressed in lumens per square foot or in footcandles. The rate at which a source emits light energy, evaluated in terms of its visual effect, is spoken of as light flux, and is expressed in lumens.

IMMERSION FOOT (TRENCH FOOT). A painful condition of the feet resulting from relatively long wet exposures at temperatures above freezing. Nerve, muscle, and blood vessel injury occurs as a result of cooling. Prevention and treatment consist of proper foot care including regular drying of the feet, shoes, and socks.

IMMINENT DANGER. An impending or threatening dangerous situation which could be expected to cause death or serious injury to persons in the immediate future unless corrective measures are taken.

IMPERVIOUS.  A characteristic of a material that does not allow another substance to pass through it or penetrate it.

IMPINGER. Glass device for drawing contaminated air through a liquid to entrap particles, solvents, and aerosols for later analysis.

IMPLOSION. A rapid expenditure of energy producing an inward burst, opposed to explosion.

INCENDIARY. A substance causing or designed to cause fires. Also, a person who willfully destroys property by fire.

INCIDENCE RATE. The number of injuries, illnesses, or lost workdays related to a common exposure base of 100 full-time workers. The common exposure base enables one to make accurate interindustry comparisons, trend analysis over time, or comparisons among firms regardless of size. This rate is calculated as:  IR = (N/EH) x 200,000.      where: N = number of injuries and/or illnesses or lost  work days, EH = total hours worked by all employees during calendar year, 200,000 = base for 100 full-time equivalent workers  (working 40 hours per week, 50 weeks per year).

INCIDENCE RATE (EPIDEMIOLOGY).  The number of new cases, per unit population, occurring during a stated time period.

INCIDENT. An unforeseen event or occurrence which does not result in injury or property damage.

INCUBATION TIME. The elapsed time between exposure to an environmental agent or microorganism and the appearance of biologic alteration.

INDEPENDENT VARIABLE. A variable that can either be set to a desired value by the investigator or observed as it naturally occurs.

INDEX CASE. The first case in a family or other defined group to come to the attention of the investigator.

INDIRECT COSTS. Monetary losses resulting from an accident other than medical costs and worker's compensation payments. (See ACCIDENT COSTS.) 

]INDIRECT DAMAGE. Loss resulting from a hazardous condition or incident but not caused directly thereby.




INDUSTRIAL HYGIENE. Industrial hygiene is that science and art devoted to the anticipation, recognition, evaluation, and control of those environmental factors or stresses arising in or from the workplace which may cause sickness, impaired health and well-being, or significant discomfort and inefficiency among workers or among the citizens of the community.

INDUSTRIAL HYGIENIST. A person with the training and ability to: a) recognize the environmental factors and stresses associated with work and work operations to understand their effect on workers and their well-being; b) evaluate, on the basis of experience and with the aid of quantitative measurement techniques, the magnitude of these stresses in terms of ability to impair worker health and well-being; and c) prescribe methods to eliminate, control, or reduce such stresses when necessary to alleviate their effects.



INDUSTRIAL VENTILATION. An integral part of a system to condition air which may be used in combination with heating, cooling, and humidifying. When used alone, it may be used to remove contaminated air from a work space and for heat control, and includes a supply system and an exhaust system.  A well-designed supply system will consist of an air inlet section, filters, heating and/or cooling eqipment, and registers/grilles for air distribution within the work space.  The exhaust system may include a general exhaust system and a local exhaust system.  (See EXHAUST, GENERAL; EXHAUST, LOCAL.)

INERT GAS NARCOSIS (NITROGEN NARCOSIS,  RAPTURE OF THE DEPTHS-). The toxic effect of the carrier or inert gas in a breathing mixture at increased pressures. It is characterized by euphoria, impaired coordination, and diminished cognitive function. Breathing air, nitrogen begins to become toxic at about 4 atmospheres absolute pressure and becomes disabling at pressures exceeding 8 atmospheres absolute. It resolves completely with decreasing pressure.

INFANT MORTALITY RATE. The number of deaths of persons under 1 year of age occurring during a stated period of time divided by the total number of live births occurring during that period of time.  This rate is often quoted as a useful indicator of the level of health in a community or nation.

INFLAMMABLE. A general term once used to describe combustible gases, liquids or solids. Now obsolete. (See FLAMMABLE.) 

INFLAMMATION. The reaction of living tissues to injury, whether by infection or trauma. The affected part becoming red, hot, painful, and swollen due to hyperaemia, exudation of fluid, etc.

INGESTION. The act or process of taking in or putting items (food, drugs, etc.) into the body. With regard to certain cells, the act of engulfing or taking up bacteria and other foreign matter.

INHALATION. The act of breathing in, or taking into the lungs, a substance in the form of a gas, vapor, fume, mist, or dust .

INHERITED ABNORMALITY. A defective character or quality transmitted from parent to offspring in the genetic material, that may continue to be passed to successive generations.

INHIBITOR. A substance or an agent that slows or prevents a chemical or organic reaction, or a material used to prevent or retard rust or corrosion.

INJURY. Physical harm or damage to a person resulting in the marring of appearance, personal discomfort, infection, and/or bodily hurt or impairment. Note: The definition of this word is frequently determined by the government agency or other organization using it.

INJURY (OCCUPATIONAL). Any acute hurt, harm or impairment to a worker that arises out of, or in the course of, employment, and is due to an external cause. The government agency which has jurisdiction determines the exact wording of the term.

INRUNNING NIP POINT. A rotating mechanism that can seize and wind up loose clothing, belts, hair, body parts, etc. It exists when two or more shafts or rolls rotate parallel to one another in opposite directions.  It also can occur between a rotating shaft and a fixed surface.

INSURABLE INTEREST. Refers to the relationship of the party of whom the insurance coverage is written to the peril being insured. The party must either own or have a financial stake in the subject that may suffer the damage or loss which would involve out-of-pocket expense to that party if no insurance indemnity was available.

INSURANCE. The making of a legal and enforceable contract between one party (called the insurer or underwriter) with another (called the insured) whereby in consideration of a  sum of money (called the premium) the insurer agrees to pay an agreed amount of money to the insured if and when the latter may suffer some loss or may be injured by some event, the happening of which is described in the contract of insurance (which is usually a  policy-).

INSURED. The person who has purchased a policy of insurance and is protected by it.

INSURED COSTS. Accident losses, which are covered by worker's compensation, medical, or other insurance programs. They comprise the insured element of the total accident cost.

INTENSITY LEVEL (SOUND). The sound-energy flux density level.  In decibels of sound, intensity level equals 10 times the logarithm to the base 10 of the ratio of the intensity of this sound to the reference intensity. (See DECIBEL.)

INTERLOCK. A device which interacts with another device or mechanism to govern succeeding operations. For example, an interlocked machine guard will prevent the machine from operating unless the guard is in its proper place. An interlock on an elevator door will prevent the car from moving unless the door is properly closed.

INTERROGATORIES. A set of formal written questions presented to a witness, usually before the trial, who must give written answers under oath.

INTERSTITIAL. (1) Pertaining to the small spaces between cells or structures; (2) occupying the interstices of a tissue or organ; (3) designating connective tissue occupying spaces between the functional units of an organ or a structure.

INTERVENING ACT. The negligent act of a third person to break the chain of causation in such a manner that the injury was not a probable consequence of the original wrongdoer's negligence.

INTERVENING AGENCY. An intermediate agency that disrupts the connection between the negligent act and the injury in such a way to supersede the original act and stand alone as the cause of injury.

INTERVENING CAUSE. An independent cause which breaks the connection between the negligent act and the injury such that it is the immediate cause of injury.

INTERVENING FORCE. One which actively produces harm after the defendant's negligent act has been committed. The word intervening- is used in a time sense to include later events, and not conditions or forces already in operation at the time of defendant's conduct. To relieve the defendant from liability for the original negligent act, it must be determined whether the intervening force was the superseding cause of injury, rather than an extraordinary cause or a cause which might reasonably have been expected.

INTERVENING LOSSES. The intrinsic value for the trouble, disadvantage, or deprivation incurred by damage to property or injury to people. Losses in addition to the material or physical losses.

INTERVENING NEGLIGENCE. The negligence of an intervening person or agency between the original negligence of the wrongdoer and the injury.

INTERVENTION STUDY. A type of epidemiologic study in which the investigator assigns, usually at random, individuals to be exposed or not to be exposed to a given factor, such as a treatment or a vaccine. These individuals are then followed through time and the proportion developing or dying from a disease among those exposed to the factor is compared to the proportion developing or dying from the disease among those  not exposed, the exposure having been determined by initial assignment.

INTOXICATION. Pertains, in medicine, to poisoning as by a drug, serum, alcohol, or any poison. Also drunkenness or the acute condition produced by over-indulgence of alcohol.

INVERSION. Phenomenon of a layer of cool air trapped by a layer of warmer air above it so that the bottom layer cannot rise.

IRRADIATION. Exposure to radiation.

IRRITANT. Any external stimulus which produces active responses in a living organism. A primary irritant is one that has been found to produce an irritating effect at the area of the skin contact. Although they affect everyone, they do not produce the same degree of irritation.

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