Glossary of terms and acronyms U-Z

The following is a glossary of some key terms, concepts and acronyms used in the publications in this and in linked web sites. The terms and definitions are drawn from a number of sources including legislation, standards, codes of practice, guides, reports and other documents. For translations into Maori of some of the key terms here, see the English-Maori Glossary of Occupational Safety and Health Terms.

If you have any suggestions for additions to the glossary, please e-mail them to the webmaster.

Term or Acronym	Definition
U-bolt	A stud threaded at both ends and bent into a 'U' shape so both threads are parallel.
UEL	Upper explosive limit. The concentration of flammable gas, vapour or mist in standard air, above which an explosive gas atmosphere will not be formed.
UHF	Ultra high frequency.
UL	The Underwriters Laboratories Inc.
ULD	See Upper Limb Disorder.
Ullage	The air space left in a container when it is nominally full so that any expansion of the liquid will not cause overflow or excessive hydraulic pressure.
Ulnar deviation	A position of the hand in which the wrist is bent towards the little finger. It is a poor working position for the hand and may cause nerve and tendon damage. It reduces the ability of arm to pronate or supinate by 50%, e.g. chopping wood.
Ultimate strength	A property of a material that corresponds with the maximum stress that a material can withstand before failing.
Unattended boiler	A boiler which can only start up, operate and shut down under the control of the boiler management system and monitoring of the safety system.
Uncertainty	Estimate attached to a measurement result which characterizes the range of values within which the true value is asserted to lie.
UNCETDG	The United Nations Committee of Experts on the Transport of Dangerous Goods.
Uncontrolled hazard	A hazard which has been identified in a hazard analysis, and for which the operator has no control measures available, and there is not a regulatory requirement to control that hazard.
UN/ECE	An abbreviation for a regulation of the United Nations Economic Commission for Europe.
UNRTDG	United Nations Recommendations for the Transport of Dangerous Goods.
Under cut	(1) A back-cut lower than the horizontal scarf cut (a dangerous practice). (2) In crosscutting, the cut made from the underside of a log.
Underground coal mine	(a) Any place where any person works below ground for the purpose of: (i) extracting any coal from the earth; or (ii) processing any coal extracted from the earth at that place; and (b) includes any place in which coal so extracted or processed is washed, crushed, or screened.
Underground service	All underground electricity, gas, water (including piped sewage), telecommunications plant, and liquid petroleum services and oil pipelines.
Underground tank (petroleum storage)	A tank capable of storing hydrocarbon products, which is installed below the surface of the ground and entirely covered with backfill and as defined in the Dangerous Goods Regulations 1985.
Undergrowth	Layer of vegetation growing under the canopy of crop trees.
Underway	Means that a vessel is not at anchor, or made fast to the shore, or aground.
UNICOM Service	A ground radio communications service in the aeronautical mobile service providing local aerodrome information for the facilitation of aviation, and, for the avoidance of doubt, a UNICOM service is not an air traffic service.
Unintentional release	Unplanned or unwanted release of a hazardous substance or substances that may or may not be detected immediately.
Union	A society of employees lawfully associated for the purpose of protecting or furthering the employment interests of employees (whether incorporated or not).
Unisex facilities	Facilities available for use by either sex.
Unit standard	A unit standard approved by the New Zealand Qualifications Authority. A unit standard is not a training course.
Unitary authority	A territorial authority that has the responsibilities, duties, and powers of a regional council conferred on it under: (a) the provisions of any Act; or (b) an Order in Council giving effect to a reorganisation scheme.
United Nations (UN) number	The identification number assigned to dangerous goods by the United Nations Committee of Experts on the Transport of Dangerous Goods and as published in the latest edition of: (a) New Zealand Standard 5433:1999, Transport of Dangerous Goods on Land; (b) United Nations Recommendations on the Transport of Dangerous Goods; (c) International Maritime Dangerous Goods Code; (d) Technical Instructions for the Safe Transport of Dangerous Goods by Air of the International Civil Aviation Organisation; (e) Dangerous Goods Regulations of the International Air Transport Association.
Universal earmuff	An earmuff that can be worn with the headband over the head, behind the head or under the chin.
Universal joint	A coupling between two shafts, capable of transmitting rotary motion from one to the other even when the shafts are placed at an angle to each other. Usually used between shafts which may change their orientation during operation.
Unladen weight	In relation to a vehicle, means the weight of the vehicle together with the fuel in its fuel system (if any) and the equipment and accessories on it that are necessary for its operation for the purpose for which it was designed.
Unprotected area	In relation to an external wall of a building means: (a) any part of the external wall which has less than the required FRR. For example, a non fire rated window, door or other opening, or sheet metal; (b) any part of the external wall which has combustible material more than 1.0mm thick attached or applied to its external face, whether for cladding or any other purpose.
Unprotected electrical equipment	Electrical equipment which, because of its design or manufacture, is not suitable for use in a potentially explosive atmosphere.
Unsealed radioactive material	A radioactive material in a form that allows it to be readily removed from its container and subdivided or dispersed.
Upper deck	The uppermost complete deck exposed to weather and sea: (a) which has permanent means of weathertight closing of all openings in the weather part thereof; and (b) below which all openings in the sides of the ship are fitted with permanent means of watertight closing. In a ship having a stepped upper deck, the lower line of the exposed deck and the continuation of that line parallel to the upper part of the deck is taken as the upper deck.
Upper limb disorders	A range of upper limb musculoskeletal disorders associated with work. Some have clear clinical and pathological diagnostic criteria. These include rotator cuff syndrome, lateral epicondylitis, medial epicondylitis, ulnar nerve entrapment, radial nerve entrapment, tendonitis in the hand and fingers, Raynaud's phenomenon or peripheral neuropathy related to upper limb vibration, De Quervain's tenosynovitis and carpal tunnel syndrome. In addition, there are many cases of upper limb pain without associated objective signs. These cases have been given many labels, including repetitive strain injury, occupational overuse syndrome (OOS) and non-specific musculoskeletal disorder of the upper limb. Usage in New Zealand ACC review and appeal cases has favoured the term 'regional pain syndrome'.
Uproot	Tree blown or pushed over with the root wad attached.
UPSS	Underground petroleum storage system.
uPVC	Un-plasticised polyvinyl chloride.
Urethane	A type of paint or polymer which results from the reaction of an isocyanate with hydroxyl containing component. Urethanes are noted for their toughness and abrasion resistance.
URL	Universal Resource Locator (worldwide web or internet address/location of file).
Urupa	Maori burial site.
Use	In relation to hazardous substance, use includes handling, storage, labelling, tracking and disposal.
User formable earplug	An earplug that is shaped by the user before insertion into the ear canal.
Useful life	May be expressed as either: (a) The period over which a depreciable asset is expected to be used; or (b) The number of production or similar units (i.e. intervals, cycles) that is expected to be obtained from the asset.
USEPA	United States Environmental Protection Agency.
UTC	Co-ordinated universal time.
UV radiation	Solar UV radiation is waves of energy generated from the sun which can cause sunburn, pre-mature ageing of the skin and cancer. Splar UV radiation can be divided into three wavelength bands: UVA (315 nm - 400 nm), UVB (280 nm - 315 nm) and UVC (100 nm - 280 nm). The earth's ozone layer absorbs all of the UVC and much of the UVB.
UV Index	An international system for reporting ultraviolet radiation intensity. The index is defined as the UV spectral irradiance weighted by the CIE action spectrum, and is given in units of watts per square metre, multiplied by 40. Simply stated, the UV Index is a measure of the amount of skin-damaging (and eye-damaging) UV radiation that reaches the earth's surface. As the UV Index number increases, so does the potential risk.
V	Volts.
Vaccine	A suspension of killed or attenuated organisms (bacteria or viruses) designed to protect the body against a specific disease by stimulating the formation of antibodies.
Vaccinate	To inoculate with a vaccine to provide immunity to a corresponding infectious disease.
Vacuum cleaning equipment	Equipment complying with the requirements of the Australian Standard numbered AS 3544-1988 and entitled 'Industrial Vacuum Cleaners for Particulates Hazardous to Health'.
Valid, in relation to a study	(a) The design of the study methodology accurately reflects the matters the study seeks to measure; and (b) the study findings can be extrapolated from the sample used in the study to a broader population.
Valuation	Estimated asset value which may depend on the purpose for which the valuation is required, it replacement value for determining maintenance levels or market value for lifecycle costing.
Valve	A device for the purpose of controlling or shutting off the flow of gas.
Valve train	An assembly of valves, pressure control devices, and other fittings that form an integrated system for flow or pressure control and safe operation of a burner.
Vapour	The gaseous form of a substance that is normally a liquid or solid, e.g. mercury, organic solvents.
Vapour barrier	A wall or other barrier constructed and placed with the objective of preventing the passage of vapour from any one place to some other place.
Vapour degreasing	The process in which a cold metal object contaminated with oil or grease is immersed in the vapour above a boiling chlorinated hydrocarbon. The solvent condenses on the object and any oil or grease contamination is washed off. The process continues until the object reaches vapour temperature, at which point no more vapour is condensed and the degreasing action of the solvent ceases.
Vapour density	The ratio of the density of the vapour compared to the density of air. The density of air is assumed to be 1.0. Vapours with a vapour density greater than 1.0 will have a tendency to stay close to the floor, whereas vapours with a vapour density less than 1.0 will tend to rise.
Vapour pressure	The pressure created when a substance evaporates. This is the pressure of the vapour of the substance, at a given temperature, in equilibrium with its solid or liquid form. The higher the vapour pressure, the more the substance tends to evaporate.
Vault	An underground structure, with a minimum volume of 1.0m3, which may be entered, and which is designed to contain piping and piping components (such as valves and pressure regulators).
VCU	Vehicle Certification Unit of the Land Transport Safety Authority.
VDU	Visual Display Unit. The monitor, keyboard and mouse and computer housing.
Vector	A living carrier which transfers an infectious agent from an infected individual (or their waste) to another individual, their food, or their immediate surroundings.
Vector control	Measures taken to decrease the number of disease carrying organisms (vectors) and to diminish the risk of their spreading infectious diseases.
Vehicle	(a) A contrivance equipped with wheels, tracks, or revolving runners on which it moves or is moved; and (b) includes a hovercraft, a skateboard, in-line skates, and roller skates; but (c) does not include (i) a perambulator or pushchair: (ii) a shopping or sporting trundler not propelled by mechanical power: (iii) a wheelbarrow or hand-trolley: (iv) a child's toy, including a tricycle and a bicycle, provided, in either case, no road wheel (including a tyre) has a diameter exceeding 355 mm: (v) a pedestrian-controlled lawnmower: (vi) a pedestrian-controlled agricultural machine not propelled by mechanical power: (vii) an article of furniture: (viii) an invalid wheel-chair not propelled by mechanical power: (ix) any other contrivance specified by the rules not to be a vehicle for the purposes of this definition.
Vehicle axle index (VAI)	A system for indicating the extent to which the axles of a motor vehicle are loaded, so that the effect of the axle weights on roads and bridges can be determined, and that is established by a road controlling authority when the vehicle is issued with an overweight permit.
Vehicle identification number (VIN)	A group of letters and numbers consisting of 17 characters that: (a) is affixed to a vehicle in accordance with the relevant standard prescribed under the Traffic Regulations 1976, and (b) is capable of being decoded to provide identifying information about that vehicle.
Vein	A vessel carrying blood to the heart.
Velocity sensor	Device which senses speed of an object or fluid.
Venereal disease	Under the Health Act defined as gonorrhoea, gonorrhoeal ophthalmia, syphilis, soft chancre, venereal warts, or venereal granuloma.
Ventilation	The supply of sufficient clean air to ensure that releases of harmful substances do not accumulate to a concentration that affects people's health and safety.
Verification	Process to specify procedures and equipment for limited tests performed over a restricted range with traceable materials or instruments on a regular basis or upon indication of need in order to detect whether the system is behaving normally or erratically with no adjustment or correction of the measurement system
Verification scheme	A documented scheme that provides a basis for ensuring that safety critical elements: (a) remain in good repair and condition; and (b) where they are yet to be provided, will be suitable.
Vermin	Any free-living animal which is not part of the normal operation of any premises. The term includes, but is not restricted to, birds, rodents, other mammals and insects.
Vertebrate toxic agent	A trade name product used to kill or reduce the viability of vertebrate animals. It does not include attractant or repellent substances that are not toxic.
Vessel	Every description of boat or craft used in navigation, whether or not it has any means of propulsion; and includes: (a) a barge, lighter, or other light vessel; (b) a hovercraft or other thing deriving full or partial support in the atmosphere from the reaction of air against the surface of the water over which it operates; (c) a submarine or other submersible.
Veterinary medicine	Any substance, mixture of substances, or biological compound used or intended for use in the direct management of an animal.
Veterinary surgeon	A person for the time being registered as a veterinary surgeon under the Veterinary Surgeons Act 1956; and includes a person who uses the title or description of a 'veterinary practitioner' under the authority of that Act.
VFR flight	A flight conducted in accordance with the visual flight rules.
VHF	Very High Frequency. Used to describe frequencies or channels in the range 30 - 300 MHz.
Vibration disorders	Disorders associated with whole-body vibration (caused by vehicle operating, especially forklifts, tractors, loaders, trucks and buses) or hand-transmitted vibration (caused by hammer drills, hand-held portable grinders and jigsaws.
Vibration white finger	A condition where the blood vessels in the hand constrict, resulting in decreased blood flow. This disease is associated with the long-term use of vibrating tools (or in general exposure to vibration). Also referred to as secondary Raynaud's phenomenon.
Victim	Under the Victims' Rights Act: (a) means: (i) a person against whom an offence is committed by another person; and (ii) a person who, through, or by means of, an offence committed by another person, suffers physical injury, or loss of, or damage to, property; and (iii) a parent or legal guardian of a child, or of a young person, who falls within subparagraph (i) or subparagraph (ii), unless that parent or guardian is charged with the commission of, or convicted or found guilty of, or pleads guilty to, the offence concerned; and (iv) a member of the immediate family of a person who, as a result of an offence committed by another person, dies or is incapable, unless that member is charged with the commission of, or convicted or found guilty of, or pleads guilty to, the offence concerned; and (b) for the purposes only of sections 7 and 8, includes: (i) a person who, through, or by means of, an offence committed by another person, suffers any form of emotional harm; and (ii) a parent or legal guardian of a child, or of a young person, who falls within subparagraph (i), unless that parent or guardian is charged with the commission of, or convicted or found guilty of, or pleads guilty to, the offence concerned; and (c) despite paragraphs (a) and (b), if an offence is committed by a person, does not include another person charged (whether as a principal or party or accessory after the fact or otherwise) with the commission of, or convicted or found guilty of, or who pleads guilty to: (i) that offence; or (ii) an offence relating to the same incident or series of incidents as that crime or offence.
Victim impact statement (VIS)	A document that advises the Court what the impact of the offence has been on the victim. It considers: (a) any physical injury or emotional harm suffered by the victim through, or by means of, the offence; and (b) any loss of, or damage to, property suffered by the victim through, or by means of, the offence; and (c) any other effects of the offence on the victim.
Vienna Convention	The United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances adopted in Vienna on 19 December 1988.
Vigilance	Having to pay attention or concentrate for long periods of time. This state of sustained alertness or vigilance is required in some jobs such as driving or flying and is especially demanding mentally.
Violence	Any action, incident or behaviour in which an employee is assaulted, threatened, harmed, injured or humiliated in circumstances related to their work, including commuting to and from work, because of the action of another person. This can involve: intentional behaviour aimed at physically injuring or assaulting an employee, leading to actual physical or psychological harm; verbal abuse, including swearing, insults or condescending language; aggressive body language indicating intimidation, contempt or disdain; harassment, including mobbing, bullying and racial or sexual harassment; expression of the intent to cause harm, including threatening behaviour, verbal and written threats.
Viral hepatitis	An infection of the liver caused by one of a wide range of viruses. Typical symptoms are fever, malaise and jaundice, although hepatitis C is often asymptomatic. In an occupational context, hepatitis B (HBV) and hepatitis C (HCV) are the most important. The main routes of exposure are percutaneous (puncturing the skin) through needle stick injuries, and across mucous membranes or damaged skin, through contact with contaminated body fluids.
Virulence	The degree of pathogenicity of a micro-organism, as indicated by the severity of the disease produced and its ability to invade the tissues of a host.
Viscera	Body organs.
Viscosity	The resistance of a fluid to flow.
Visibility	The ability, as determined by atmospheric conditions and expressed in units of measurement, to see and identify prominent unlighted objects by day and prominent lighted objects by night.
Visible light transmittance (VLT)	The proportion of visible light that passes through glazing, measured perpendicular to the glazing. Overall VLT is the VLT of the glazing together with any overlays.
Vision	A declaration of the ideal conditions: how things would look if the issue important to you was perfectly addressed.
Visor	Shield (made from plastic or mesh) that encloses the front and sides of the wearer's face. Visors are generally fitted to safety helmets.
Visual acuity	The ability to focus the eyes clearly.
VOC	Volatile organic compounds (VOCs) are emitted directly (for example, fuel evaporation from vehicles and service stations) and during combustion processes. Biogenic VOCs are naturally emitted by vegetation.
Vocationally independent	An injured person who has the ability following rehabilitation to get a job.
Vocational medical assessment	Assessment of an injured claimant's suitability to return to work, including alternate employment if they are unable to return to their old job.
Vocational rehabilitation	ACC help for a claimant to maintain employment, obtain employment, or maintain or obtain vocational independence (able to get a job after an injury).
Volatile	Able to pass readily into the vapour state.
Volatile organic compounds	Large and diverse group of chemicals, including hydrocarbons oxygenates and halocarbons, including 1, 3-butadiene, benzene toluene, xylenes, styrene, some PAHs, formaldehyde, methyl ethyl ketone, methyl isobutyl ketone, dichloromethane, dichlorobenzene, tetrachloroethylene and acrylonitrile.
Volatility	The tendency of a solid or liquid material to pass into the vapour state at a given temperature in °C. Specifically, the vapour pressure of a component divided by its mole fraction (gram molecular weight) in the liquid or solid.
VOLMET	Meteorological information for aircraft in flight.
Voltage	The pressure of the electrical power supply. The unit of pressure of the electricity supply is the Volt, or V. For example household electricity is supplied at 230 V.
Volunteer	A person who: (a) does not expect to be rewarded for work to be performed as a volunteer; and (b) receives no reward for work performed as a volunteer. Does not include a person who is in a place of work for the purpose of receiving on-the-job training or gaining work experience.
Volunteer diver	A person present in a place of work who does not expect to receive any gain or reward for the diving activity taking place. Please note: The definition of 'volunteers' does not include those who are receiving training or gaining work experience.
Volunteer fire brigade	Any group of persons associated by mutual consent as a fire brigade where: (a) those persons have entered as a group into a binding agreement of service with the NZ Fire Service Commission; and (b) that group of persons is registered as a volunteer fire brigade under the Fire Service Act.
Vote: Labour	Money voted to DOL by Parliament in the Budget.
VTA	Vertebrate toxic agent.
VTS	Vessel Traffic Services.
Vulnerable facility	Any of the following facilities: (a) buildings of 4 storeys or more, of curtain wall construction with panels greater than 1 500 mm square: (b) buildings of 4 storeys or more with more than 50% of the wall area glazed: (c) any hospital (as defined in the Hospitals Act 1957), early childhood centre (as defined in section 308 of the Education Act 1989), or school (as defined in section 145 of the Education Act 1989): (d) public buildings or structures of historic value: (e) major traffic terminals such as railway stations and air ports handling more than 1 800 people in 24 hours: (f) major public utilities whose service could be disrupted by a blast of 5 kPa: (g) any similar facilities.
V/V	A measure of content of a liquid in a liquid (in solution) (volume per volume).
W/V	A measure of content of a solid in a solution (weight per volume).
WSMP	Workplace Safety Management Practices.
W/W	A measure of content of a solid in a solid (weight per weight).
Wahi tapu	Sites of significance to Maori, including those of sacred and cultural significance.
Waka ama	Outrigger canoe. A waka ama consists of a hull with one or more outrigger pontoons (ama), rigged out to the side for stability and lashed to the hull with cross beam members (kiato). The hull has sealed bow (ihu) bulkheads and stern (kei) bulkheads.
Waka taurua	Double-hulled canoe. A waka taurua is a vessel with two hulls lashed together with kiato for stability.
Waka tere	Sailing canoe. A tere is a waka ama fitted/rigged with a mast, a sail and appropriate sailing kiato. The waka tere also has a special sailing ama for the purpose of sailing.
Waling	A horizontal beam supporting vertical timbers, runners or sheeting.
Warm location	A location in New Zealand where the degree-day total is less than 920.
Warning	Applied in the context of safety signs to a situation which is likely to be hazardous but but not likely to be life-threatening if the message is ignored.
Warrant	Documentation specifying the functions that the enforcement officer may carry out.
Warrant of fitness (WoF)	Evidence of vehicle inspection issued to a vehicle under the Land Transport Rule: Vehicle Standards Compliance.
Waste	Any material, solid, liquid or gas that is unwanted and/or unvalued, discarded or discharged (as defined in the New Zealand Waste Strategy).
Waste audit	A systematic, documented, periodic and objective evaluation of an organisation's performance in managing waste.
Wastewater services	Sewerage, treatment and disposal of sewage, and stormwater drainage.
Water capacity	The volume of water at 15°C that fills a compressed gas container that is fitted for use with any valve, dip tube, float, or other necessary fittings.
Water dew point	Temperature above which no condensation of water occurs at a specified pressure. NOTE: For any pressure lower than the specified pressure there is no condensation at this dew point temperature.
Water reactive	Substances that react violently when in contact with water. They may be either be flammable solids or corrosives.
Water safety sector	A general term used to cover all the individuals, groups, agencies and organisations with interest in or responsibility for water safety issues.
Water supply	The provision of drinking water to communities by network reticulation to the point of supply of each dwellinghouse and commercial premise to which drinking water is supplied.
Water trap	A fitting designed to retain a depth of water that prevents foul air and gases escaping from the plumbing system or foul water drainage system and entering a building.
Watt	The unit of power, usually expressed as Watt or W. The appropriate power supply is marked on the nameplate, e.g. a heater may be labelled 2,300 W, a light bulb may be labelled 60 W.
Weapons system	Any ammunition, explosive, or propellant; and includes any platform designed to carry any combination thereof.
Weather deck	A ship's deck that is exposed to the weather and sea.
Web part	A modular unit of information that has a single purpose and that forms the basic building block of a Web Part Page. A web part consists of a bar, a frame and content.
Wedge	A tapered plastic, steel, or aluminium alloy tool which is driven into a back cut by a hammer to prevent the tree from sitting back on the back cut, or to force it towards the desired direction of fall.
Welder, certified	A welder who holds current welding certification approved to NZS 4711 (or equivalent) in the position(s) appropriate to the welding task.
Welding	Connection of two solids by the liquefaction, followed by solidification, of material which joins them.
Well	A fully or partially lined hole in the ground.
Well (petroleum)	(a) A borehole that is intended to intersect petroleum-bearing strata; and (b includes any borehole for re-injection purposes.
Well-drilling operation (petroleum)	Any operation in connection with the drilling of, or in, a well; and includes: (a) the making, completion, suspension, or abandonment of a well; and (b) the deepening, repair, or re-drilling of a well; and (c) any operation that renders any part of the primary pressure containment system of the well inactive or inoperable; and (d) any on-site operation ancillary to the making, completion, suspension, or abandonment of a well, whether or not before, during, or after the actual making, completion, suspension, or abandonment takes place.
Well point system	A system of pipes, jetted or driven at close centres into the ground and connected to suction main for the purpose of lowering ground water, particularly in granular soil.
Wellhead	A set of valves and other pressure-rated components, connected to the top of the geothermal well and used to contain the well fluids.
Wellness	A dimension of health beyond the absence of disease or infirmity, including social, emotional and spiritual aspects of health.
WES	Workplace Exposure Standard.
Wettable powder	A powder formulation to be applied as a suspension after dispersion in water.
Whanau	Extended family, family group.
Wheel	A rotating load-carrying member between the tyre and the hub, which usually consists of two major parts, the rim and the wheel disc, which may be manufactured as one part, or permanently attached to each other, or detachable from each other; and includes the tyre fitted to the rim.
Wheel centre-disc	That part of the wheel that is the supporting member between the hub and the rim.
Wheeled loader	A four-wheeled, articulated machine equipped with loading forks.
Wheel offset	Distance from the rim centreline to the inner (hub contact) face of the wheel disk, measured in millimetres. A wheel with a positive offset will have the centreline inboard of the contact face, whereas a wheel with negative offset will have the wheel centreline outboard of the contact face.
Wheel spacer	An additional component used for the purpose of positioning the wheel centre-disc relative to the hub, or in multiple wheel sets, for the purpose of positioning the wheel centre-disc relative to another wheel.
Wheelbase	The distance from a vehicle's rear axis to its front axis.
WHO	World Health Organisation.
WHO guideline values	An indication of the concentrations of a substance to which people may be exposed without adverse health effects; set by the WHO.
Wholesome	In relation to water, means complying with the standards in the Ministry of Health document Drinking Water Standards for New Zealand 1995.
Whorl	Ring of branches emerging from a tree stem.
Winch	A powered drum used to reel in or pay out rope.
Wind chill	The effect of wind speed in increasing the cooling effect of air temperature. It is expressed as the still air temperature giving the same cooling effect.
Wind wrenched	Trees blown over by the wind, but still standing. Stems may be severely bent
Windfall	An individual tree blown down by the wind.
Window trough	That part of the window sill below both the upper and lower vertical sliding sashes of sash windows, or the area of the sill or frame covered by a closed casement or top hung window.
Windrowing	Moving the slash on the cutover into long parallel piles.
Windscreen	All glazing extending across the front of the vehicle that is not parallel to the vehicle's longitudinal centre-line; but does not include a wind deflector.
Windthrow	Trees blown down by the wind. Stems have been snapped or the rootplate has rotated out of the ground.
Wing cuts	Cuts made into the wood of the stump area to minimise side slabbing. They are made on each side, beneath the base of the scarf and at an angle greater than 60°.
Wing nut	A nut formed with two projections or 'wings' for tightening by hand.
Wire glass	Glass that incorporates reinforcing wire mesh.
WLL	Working load limit. Normally relates to SWL and is the same, however, refer to manufacturers' specifications.
WMA	World Medical Association.
Woodworking machine	(a) A band re-saw, borer, chipper, circular saw, profile copying machine, debarker, edger,frame saw, log band saw, log carriage, mortising machine, moulder, narrow blade band saw, planing machine, router, sander, tenoning machine, trencher, or wood turning machine; (b) Any machine designed to be fitted with a cutter and used either for: Breaking down a log to boards; or The further processing of sawn timber, wood, wood products, fibre board, or any other material, including aluminium, used in the place of wood in the building, construction, joinery or furniture manufacturing industry.
Work	Physical or mental effort directed towards doing or making something. Paid employment at a job or trade, occupation or profession.
Work-conditioned pauses	Those interruptions that arise either from the operation of the machine or the organisation of the work, e.g. waiting for the machine to complete a phase of its operation, or for a tool to cool down, etc. Work-conditioned pauses are breaks in work caused by system or process, e.g. waiting to fill boxes on a conveyor belt.
Work involving asbestos	(a) Work involving the cleaning, disposal, handling, processing, storage, use, or working of asbestos; or (b) work involving the demolition or maintenance of any thing, including a building or a part of a building, containing asbestos; or (c) cleaning work carried out as a consequence of, or in connection with, work specified in paragraph (a) or paragraph (b).
Work lamp	A high-intensity lamp, which is not necessary for the operation of the vehicle but is designed to illuminate a work area or scene; and includes: (a) a scene lamp; and (b) a spot lamp; and (c) an alley lamp.
Work organisation factors	The way in which work is structured, supervised and processed. It deals with the institutional features of work such as the nature of the organisational chart, who is the boss, power, authority, responsibilities, how work gets done, the nature of tasks including such features as workload and content. It is the objective nature of the work process.
Work platform	A platform intended to provide safe working conditions and designed to be mounted on a high lift fork truck or other elevating device, providing an areas for person(s) elevated by and working from the platform safety work surface.
Work practice controls	Controls that reduce the likelihood of exposure to hazards by altering the manner in which a task is performed (e.g., prohibiting the two-handed technique for the recapping of needles after use, or prohibiting the drop starting of chainsaws).
Workers Memorial Day	Day started by American and Canadian workers in 1989 in order to commemorate dead and injured workers annually on 28 April.
Working alone	Work carried out in an area where normal means of contact (e.g. verbal, sight) with other staff are not available, so that the potential risk of existing hazards is increased to the extent that extra precautions are needed. This may include working in isolated areas on- or off-site, either during or outside normal working hours.
Work-related homicide	Death due to fatal injury deliberately caused by another person and sustained in the course of work.
Work-related non-fatal assault	A non-fatal injury deliberately caused by another person and sustained in the course of work.
Work-related personal injury	A work-related personal injury is a personal injury that a person suffers: (a) while he or she is at any place for the purposes of his or her employment, including, for example, a place that itself moves or a place to or through which the claimant moves; or (b) while he or she is having a break from work for a meal or rest or refreshment at his or her place of employment; or (c) while he or she is travelling to or from his or her place of employment at the start or finish of his or her day's work, if he or she is an employee and if the transport (i) is provided by the employer; and (ii) is provided for the purpose of transporting employees; and (iii) is driven by the employer or, at the direction of the employer, by another employee of the employer or of a related or associated employer; or (d) while he or she is travelling, by the most direct practicable route, between his or her place of employment and another place for the purposes of getting treatment for a work-related personal injury, if the treatment (i) is necessary for the injury; and (ii) is treatment of a type that the claimant is entitled to under Part 1 of Schedule 1. Work-related personal injury includes: a cardio-vascular or cerebro-vascular episode suffered by a person, if the episode is caused by physical effort or physical strain, in performing his or her employment, that is abnormal in application or excessive in intensity for the person; personal injury caused by a work-related gradual process, disease, or infection; personal injury suffered by a person resulting from treatment for a work-related personal injury. [IPRC Act]
Work-related suicide	Intentional self-harm, which intentionally results in death, resulting from work-related exposures or effects. It is a controversial concept because of debate over the extent and nature of connections that demonstrate a link to work.
Working cargo	Means: (a) loading cargo on to or unloading cargo from a ship; or (b) handling cargo on a ship; or (c) handling cargo on a wharf or in a transit shed within the limits of a harbour.
Workplace	A place at which a person works. Includes mobile workplaces such as road vehicles, aircraft and ships.
Workplace accident register	Book for recording serious and non-serious harm in the workplace.
Worksite assessment	A comprehensive analysis of an individual's job, work technique, workload, workstation, equipment, etc. The written report of the worksite assessment should include a summary of main findings and a recommended action plan.
Workstation	(1) The desk, chair and so on at which a VDU is used. (2) The entire area accessed by a worker when performing a specific task or job cycle.
Working cargo	Means: (a) Loading cargo on to or unloading cargo from a ship; or (b) Handling cargo on a ship; or (c) Handling cargo on a wharf or in a transit shed within the limits of a harbour.
Working channel or frequency	The channel (for VHF) or frequency (for MF/HF) on which marine radio communications are carried out after initial contact has been established on the calling frequency or channel.
Working day	Any day except: (a) a Saturday, a Sunday, Good Friday, Easter Monday, Anzac Day, Labour Day, the Sovereign's birthday, and Waitangi Day; and (b) a day in the period commencing on the 20th day of December in any year and ending with the 15th day of January in the foillowing year.
Working drum	A drum that can reel a rope in or out during a hauling cycle.
Working height	Generally the height at which the hands are positioned, e.g., the working height for a supermarket checkout operator would probably be somewhere between 5-20cm above the height of the checkout bench. The most favourable working height for handwork while standing is 50-100mm below elbow level. Working height will vary depending on the stature of the worker and the nature of the work. Delicate work is generally done higher than heavier work.
Working platform	That part of a scaffolding on which workers and/or materials are supported for the purpose of carrying out construction work.
Working pressure	In relation to gas cylinders, a non-preferred term whose definition may vary with each example. Unless otherwise defined, to be taken as the filling pressure for permanent gases.
Working technique	The way a person uses their body (parts) to do their work. Having a good posture, keeping joints straight, using momentum to help get the work done, and using smooth actions are a few examples of good technique.
Workplace Exposure Standard (WES)	The maximum concentration of a substance in a worker's breathing zone that, on the basis of present knowledge, will not cause adverse health effects. Three categories of Threshold Limit Value (TLV) exist: (a) The Threshold Limit Value - Time Weighted Average (TLV-TWA) - the time-weighted average concentration for a normal 8-hour work day and a 40-hour work week, to which nearly all workers may be repeatedly exposed, day after day, without adverse effect. (b) Threshold Limit Value - Short Term Exposure Limit (TLV-STEL) - the concentration to which workers can be exposed continuously for a short period of time without suffering from (l) irritation; (2) chronic or irreversible tissue damage; or (3) narcosis of sufficient degree to increase the likelihood of accidental injury, impair self-rescue or materially reduce work efficiency, and provided that the daily TLV-TWA is not exceeded. It is not a separate independent exposure limit; rather it supplements the time- weighted average (TWA) limit where there are recognised acute effects from a substance whose toxic effects are primarily of a chronic nature. STELs are recommended only where toxic effects have been reported from high short-term exposures in either humans or animals. A STEL is defined as a 15-minute time-weighted average exposure which should not be exceeded at any time during a workday even if the 8-hour time-weighted average is within the TLV. Exposures at the STEL should not be longer than 15 minutes and should not be repeated more than once per day. An averaging period other than 15 minutes may be recommended when this is warranted by observed biological effects. (c) Threshold Limit Value - Ceiling (TLV-C) - the concentration that should not be exceeded during any part of the working exposure.
Workplace monitoring	Assessing the amount of physical, chemical or biological agent in the workplace, e.g. the concentration of fumes in the air.
Workplace productivity	How firms can utilise labour and skills, innovation, technology and workplace organisation to improve the quantity and quality of their output.
Workspace envelope	The limit to functional reach in 3D space. How far someone can reach from a certain position, e.g., the area controls can be placed in a car that the driver can reach.
World Day for Safety and Health at Work	The day chosen by the ILO to promote the concept of creating and sustaining a safety and health culture at work. It is held on 28 April.
Worm and wheel	A type of gearing system used when very large reduction in speed is required. The worm is a small gear resembling a course screw thread, which meshes with the teeth on the rim of the wheel, which is of larger diameter. The shaft carrying the worm gear is perpendicular to the shaft carrying the 'wheel' and off-set from it. The 'worm' is rotated thus turning the wheel around at a slower rate.
Wrap	To turn a rope around a drum, log or stump.
Wrapping	The action of two moving ropes winding around each other.
Wrist extension	Posture where hand and wrist are bent up from a horizontal plane. Movement of hand towards back. Painting provides a good example.
Wrist flexion	Posture where hand and wrist are bent down from a horizontal plane. Movement of hand towards palm. Painting provides a good example. In both postures, tendons are forced to curve around structures in the wrist. Resultant friction can lead to early fatigue and injury.
Wrist-rest	A support for the heel of the hand placed adjacent to the keyboard at about spacebar .
Written authority	A document which permits entry to or work in a confined space. Note: the written authority is sometimes known by other names, for example as an entry permit, an access authority, or a permit to work.
WSE Programme	Workplace Safety Evaluation programme (ACC), designed to help employers with much higher than average injury statistics improve the safety of their workplaces.
WSNZ	Water Safety New Zealand Inc.
X-rays	X-rays produced by radioactive materials are photons radiated during a nuclear transformation after an orbital electron has been removed and another orbital electron falls down into the vacancy, emitting the difference in binding energy as a photon.
XRF	X-ray fluorescence.
Yarder	(Synonym: Hauler) A machine equipped with winch or winches which operates from a set position to haul logs or drags from the stump to landing.
Years of life lost (YLL)	An indicator of the social burden of fatal health outcomes, calculated by subtracting the age at death from the life expectancy remaining at that age (as determined from a suitable standard or reference life table).
Yellow tipping	Incomplete gas combustion where excess hydrocarbons can possibly result in unacceptable levels of carbon monoxide being produced. NOTE: This may result in soot deposition and continual deterioration of combustion.
Yield strength	A property of a material that corresponds with the maximum stress that a material can withstand before permanent deformation (dimensional change) occurs.
Yoke	The heavy U-shaped part of a block by which the block is attached to a fixed point.
Young person	A boy or girl of or over the age of 14 years but under 17 years; but does not include any person who is or has been married.
Zero energy	The state where all sources of energy including electrical, pneumatic, hydraulic, mechanical and stored energy are isolated so that they pose no danger.
Zero regulator	A gas pressure regulator that operates at an outlet pressure of zero or near-zero gauge or (atmospheric) pressure, usually in conjunction with an air-gas proportioning device.
Zipper (effect)	The splitting of the sidewall of a tyre under inflation. The tyre bursts with a long narrow opening, ejecting wire and rubber shrapnel.
Zoonosis	A disease of animals that may be transmitted to humans under natural conditions (e.g. TB, leptospirosis). Zoonoses include infection caused by viruses, fungi, parasites and bacteria.