OSHA Dictionary

Including Definitions from:

Part 1903 - Inspections, Citations, and Proposed Penalties

Part 1904 - Recording and Reporting Occupational Injuries and Illnesses

Part 1910 - General Industry

Part 1926 - Construction

Changing the Complex Into Compliance®

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Action level

AA-frame The term "A-frame" means a structure made of two independent columns

fastened together at the top and separated at the bottom for stability.(§1910.265(b)(1))

A-frame derrick means a derrick in which the boom is hinged from a cross mem-ber between the bottom ends of two upright members spread apart at the lowerends and joined at the top; the boom point secured to the junction of the sidemembers, and the side members are braced or guyed from this junction point.(§1910.181(a)(2))

Abatement means action by an employer to comply with a cited standard or reg-ulation or to eliminate a recognized hazard identified by OSHA during aninspection. (§1903.19(b)(1))

Abatement date means: For an uncontested citation item, the later of:

The date in the citation for abatement of the violation; The date approved by OSHA or established in litigation as a result of apetition for modification of the abatement date (PMA); or The date established in a citation by an informal settlement agreement.

For a contested citation item for which the Occupational Safety and HealthReview Commission (OSHRC) has issued a final order affirming the viola-tion, the later of:

The date identified in the final order for abatement; or The date computed by adding the period allowed in the citation for abate-ment to the final order date; The date established by a formal settlement agreement. (§1903.19(b)(2))

Abrasive A solid substance used in an abrasive blasting operation. (§1910.94(a)(1)(i);1926.57(f)(1)(i))

Abrasive blasting The forcible application of an abrasive to a surface by pneumatic pres-sure, hydraulic pressure, or centrifugal force. (§§1910.94(a)(1)(xii); 1926.57(f)(1)(xii))

Abrasive-blasting respirator A respirator constructed so that it covers the wearer'shead, neck, and shoulders to protect him from rebounding abrasive.(§§1910.94(a)(1)(ii); 1926.57(f)(1)(ii))

Abrasive cutting-off wheels Organic-bonded wheels, the thickness of which isnot more than one forty-eighth of their diameter for those up to, and including, 20inches (50.8 cm) in diameter, and not more than one-sixtieth of their diameter forthose larger than 20 inches (50.8 cm) in diameter, used for a multitude of opera-tions variously known as cutting, cutting off, grooving, slotting, coping, and joint-ing, and the like. The wheels may be "solid" consisting of organic-bondedabrasive material throughout, "steel centered" consisting of a steel disc with a rimof organic-bonded material molded around the periphery, or of the "inserted tooth"type consisting of a steel disc with organic-bonded abrasive teeth or insertsmechanically secured around the periphery. (§§1910.94(b)(1)(i); 1926.57(g)(1)(i))

Abrasive wheel means a cutting tool consisting of abrasive grains held togetherby organic or inorganic bonds. Diamond and reinforced wheels are included.(§1910.211(b)(14))

Absolute filter is one capable of retaining 99.97 percent of a mono disperseaerosol of 0.3 µm particles. (§1910.1003(b))

Absolute pressure (p.s.i.a.) The sum of the atmospheric pressure and gaugepressure (p.s.i.g.). (§1926.804(l))

Accept Any device, equipment, or appliance that is either approved by MSHAand maintained in permissible condition, or is listed or labeled for the class andlocation under Subpart K of this part. (§1926.800(u))

Acceptable [1910] An installation or equipment is acceptable to the Assistant Secretary ofLabor, and approved within the meaning of Subpart S:

If it is accepted, or certified, or listed, or labeled, or otherwise determined tobe safe by a nationally recognized testing laboratory; orWith respect to an installation or equipment of a kind which no nationallyrecognized testing laboratory accepts, certifies, lists, labels, or determinesto be safe, if it is inspected or tested by another Federal agency, or by aState, municipal, or other local authority responsible for enforcing occupa-tional safety provisions of the National Electrical Code, and found in compli-ance with the provisions of the National Electrical Code as applied inSubpart S; orWith respect to custom-made equipment or related installations which aredesigned, fabricated for, and intended for use by a particular customer, if it isdetermined to be safe for its intended use by its manufacturer on the basis of

test data which the employer keeps and makes available for inspection to theAssistant Secretary and his authorized representatives. Refer to §1910.7 fordefinition of nationally recognized testing laboratory. (§1910.399)

[1926] An installation or equipment is acceptable to the Assistant Secretary ofLabor, and approved within the meaning of Subpart K:

If it is accepted, or certified, or listed, or labeled, or otherwise determined tobe safe by a qualified testing laboratory capable of determining the suitabil-ity of materials and equipment for installation and use in accordance withthis standard; orWith respect to an installation or equipment of a kind which no qualified test-ing laboratory accepts, certifies, lists, labels, or determines to be safe, if it isinspected or tested by another Federal agency, or by a State, municipal, orother local authority responsible for enforcing occupational safety provisionsof the National Electrical Code, and found in compliance with those provi-sions; orWith respect to custom-made equipment or related installations which aredesigned, fabricated for, and intended for use by a particular customer, if it isdetermined to be safe for its intended use by its manufacturer on the basisof test data which the employer keeps and makes available for inspection tothe Assistant Secretary and his authorized representatives. (§1926.449)

Acceptable entry conditions means the conditions that must exist in a permitspace to allow entry and to ensure that employees involved with a permit-required confined space entry can safely enter into and work within the space.(§1910.146(b))

Accepted [1910] An installation is "accepted" if it has been inspected and found by anationally recognized testing laboratory to conform to specified plans or to pro-cedures of applicable codes. (§1910.399)[1926] An installation is "accepted" if it has been inspected and found to besafe by a qualified testing laboratory. (§1926.449)

Accepted engineering practices means those requirements which are compat-ible with standards of practice required by a registered professional engineer.(§1926.650(b))

Access means the right and opportunity to examine and copy. (§1910.1020(c)(1))Accessible

(As applied to equipment) (SEE ALSO "Readily accessible") Admitting closeapproach; not guarded by locked doors, elevation, or other effective means.(§§1910.399; 1926.449)(As applied to wiring methods) (SEE ALSO "Concealed;" "Exposed") Capa-ble of being removed or exposed without damaging the building structure or fin-ish, or not permanently closed in by the structure or finish of the building.(§§1910.399; 1926.449)

Accessory An accessory is a secondary part or assembly of parts which contrib-utes to the overall function and usefulness of a machine. (§1910.180(a)(5))

Accuracy A measure of the bias of a data set. Bias is a systematic error that iseither inherent in a method or caused by some artifact or idiosyncrasy of themeasurement system. Bias is characterized by a consistent deviation (positive ornegative) in the results from an accepted reference value. (§1910.1027 App F)

Acfm Actual cubic feet per minute. (§1910.402)Acrylonitrile or AN means acrylonitrile monomer, chemical formula CH2=CHCN.

(§1910.1045(b))Act

[1903] means the Williams-Steiger Occupational Safety and Health Act of1970 (84 Stat. 1590 et seq., 29 U.S.C. 651 et seq.). (§1903.22(a))[1904] The Act means the Occupational Safety and Health Act of 1970 (29U.S.C. 651 et seq.). The definitions contained in section 3 of the Act (29 U.S.C.652) and related interpretations apply to such terms when used in this Part1904. (§1904.46)[1910] means the Williams-Steiger Occupational Safety and Health Act of1970 (84 Stat. 1590). (§1910.2(a))[1926] means section 107 of the Contract Work Hours and Safety StandardsAct, commonly known as the Construction Safety Act (86 Stat. 96; 40 U.S.C.333). (§1926.32(a))

Actinolite SEE “Tremolite, Anthophyllite, and Actinolite”Action level

[Acrylonitrile] means a concentration of AN of 1 ppm as an eight (8)-hourtime-weighted average. (§1910.1045(b))[Benzene] means an airborne concentration of benzene of 0.5 ppm calculatedas an 8-hour time-weighted average. (§1910.1028(b))[1,3-Butadiene] means a concentration of airborne BD of 0.5 ppm calculatedas an eight (8)-hour time-weighted average. (§1910.1051(b))(AL) [Cadmium] is defined as an airborne concentration of cadmium of 2.5micrograms per cubic meter of air (2.5 µg/m3), calculated as an 8-hour time-weighted average (TWA). (§§1910.1027(b); 1926.1127(b))[Ethylene oxide] means a concentration of airborne EtO of 0.5 ppm calcu-lated as an eight (8)-hour time-weighted average. (§1910.1047(b))[Formaldehyde] means a concentration of 0.5 part formaldehyde per millionparts of air(0.5 ppm) calculated as an eight (8)-hour time-weighted average(TWA) concentration. (§1910.1048(b))[Inorganic arsenic] means a concentration of inorganic arsenic of 5 micro-grams per cubic meter of air (5 µg/m3) averaged over any eight(8) hour period.(§1910.1018(b))[Lead] means employee exposure, without regard to the use of respirators, toan airborne concentration of lead of 30 micrograms per cubic meter of air (30µg/m3) calculated as an 8-hour time-weighted average (TWA). (§§1910.1025(b);1926.62(b))[Methylene chloride] means a concentration of airborne MC of 12.5 partsper million (ppm) calculated as an eight (8)-hour time-weighted average(TWA). (§1910.1052(b))[Methylenedianiline] means a concentration of airborne MDA of 5 ppb as aneight (8)-hour time-weighted average. (§§1910.1050(b); 1926.60(b))

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Actual slope

[Occupational exposure to hazardous chemicals in laboratories]means a concentration designated in 29 CFR Part 1910 for a specific sub-stance, calculated as an eight (8)-hour time-weighted average, which initiatescertain required activities such as exposure monitoring and medical surveil-lance. (§1910.1450(b))[Occupational noise exposure] An 8-hour time-weighted average of 85decibels measured on the A-scale, slow response, or equivalently, a dose offifty percent. (§1910.95 App I)[Vinyl chloride] means a concentration of vinyl chloride of 0.5 ppm averagedover an 8-hour work day. (§1910.1017(b)(1))

Actual slope means the slope to which an excavation face is excavated. (§1926Subpart P App B)

Adjacent area means any area within 20 feet (6.1m) of a vapor area that is notseparated from the vapor area by tight partitions. (§1910.123(d))

Adjustable barrier guard means a barrier requiring adjustment for each job ordie setup. (§1910.211(d)(36))

Adjustable suspension scaffold means a suspension scaffold equipped with ahoist(s) that can be operated by an employee(s) on the scaffold. (§1926.450(b))

Administration means the Occupational Safety and Health Administration.(§1926.32(e))

Adobe blasting SEE “Mud-capping”Aerated solid powders Aerated powders shall mean any powdered material

used as a coating material which shall be fluidized within a container by pass-ing air uniformly from below. It is common practice to fluidize such materials toform a fluidized powder bed and then dip the part to be coated into the bed in amanner similar to that used in liquid dipping. Such beds are also used assources for powder spray operations. (§§1910.107(a)(1); 1926.66(a)(1))

Aerial device Any vehicle-mounted device, telescoping or articulating, or both,which is used to position personnel. (§1910.67(a)(1))

Aerial ladder An aerial device consisting of a single- or multiple-section extensi-ble ladder. (§1910.67(a)(2))

Aerial lifts Aerial lifts include the following types of vehicle-mounted aerial devicesused to elevate personnel to jobsites above ground:

Extensible boom platforms,Aerial ladders,Articulating boom platforms,Vertical towers,A combination of any of the above defined in ANSI A92.2-1969, which isincorporated by reference as specified in §1910.6. These devices are madeof metal, wood, fiberglass reinforced plastic (FRP), or other material; arepowered or manually operated; and are deemed to be aerial lifts whether ornot they are capable of rotating about a substantially vertical axis.(§1910.268(s)(1))

Aerial splicing platform This consists of a platform, approximately 3 ft. X 4 ft.,used to perform aerial cable work. It is furnished with fiber or synthetic ropes forsupporting the platform from aerial strand, detachable guy ropes for anchoringit, and a device for raising and lowering it with a handline. (§1910.268(s)(2))

Aerial tent A small tent usually constructed of vinyl coated canvas which is usu-ally supported by light metal or plastic tubing. It is designed to protect employ-ees in inclement weather while working on ladders, aerial splicing platforms, oraerial devices. (§1910.268(s)(3))

Aerosol shall mean a material which is dispensed from its container as a mist,spray, or foam by a propellant under pressure. (§1910.106(a)(1))

Affected employee An employee whose job requires him or her to operate or use amachine or equipment on which servicing or maintenance is being performedunder lockout or tagout, or whose job requires him or her to work in an area inwhich such servicing or maintenance is being performed. (§§1910.147(b), .269(x))

Affected employees means those employees who are exposed to the hazard(s)identified as violation(s) in a citation. (§1903.19(b)(3))

After-flame means the time a test specimen continues to flame after the flamesource has been removed. (§1910.155(c)(1))

Aggressive method means removal or disturbance of building material by sand-ing, abrading, grinding or other method that breaks, crumbles, or disintegratesintact ACM. (§1926.1101(b))

Air-purifying respirator means a respirator with an air-purifying filter, cartridge,or canister that removes specific air contaminants by passing ambient airthrough the air-purifying element. (§1910.134(b))

Airline respirator SEE “Supplied-air respirator (SAR) or airline respirator”Alive or live (Energized) Electrically connected to a source of potential differ-

ence, or electrically charged so as to have a potential significantly differentfrom that of the earth in the vicinity. The term "live" is sometimes used in theplace of the term "current-carrying," where the intent is clear, to avoid repetitionof the longer term. (§§1910.268(s)(4); 1926.960(a))

Aluminum hydraulic shoring means a pre-engineered shoring system com-prised of aluminum hydraulic cylinders (crossbraces) used in conjunction withvertical rails (uprights) or horizontal rails (wales). Such system is designed spe-cifically to support the sidewalls of an excavation and prevent cave-ins.(§1926.650(b))

Amended water means water to which surfactant (wetting agent) has beenadded to increase the ability of the liquid to penetrate ACM. (§1926.1101(b))

American table of distances (also known as Quantity Distance Tables) meansAmerican Table of Distances for Storage of Explosives as revised and approvedby the Institute of the Makers of Explosives, June 5, 1964. (§1926.914(a))

Ampacity [1910] Current-carrying capacity of electric conductors expressed in amperes.(§1910.399)[1926] The current in amperes a conductor can carry continuously under theconditions of use without exceeding its temperature rating. (§1926.449)

Amphibole A family of minerals whose crystals are formed by long, thin unitswhich have two thin ribbons of double chain silicate with a brucite ribbon inbetween. The shape of each unit is similar to an "I beam". Minerals important inasbestos analysis include cummingtonite-grunerite, crocidolite, tremolite-actin-olite and anthophyllite. (§§1910.1001 App J; 1926.1101 App K)

Analysis using exposure or medical records means any compilation of dataor any statistical study based at least in part on information collected from indi-vidual employee exposure or medical records or information collected fromhealth insurance claims records, provided that either the analysis has beenreported to the employer or no further work is currently being done by the per-son responsible for preparing the analysis. (§1910.1020(c)(2))

Anchorage [Fall protection] means a secure point of attachment for lifelines, lanyards ordeceleration devices. (§1926.500(b))[Powered platforms for building maintenance/Personal fall arrestsystem] means a secure point of attachment for lifelines, lanyards or deceler-ation devices, and which is independent of the means of supporting or sus-pending the employee. (§1910.66 App C)

Anchored bridging means that the steel joist bridging is connected to a bridgingterminus point. (§1926.751)

Anemometer means an instrument for measuring wind velocity. (§1910.66(d))Angle indicator (Boom) An “angle indicator (Boom)” is an accessory which

measures the angle of the boom to the horizontal. (§1910.180(a)(8))Angle of loading is the inclination of a leg or branch of a sling measured from

the horizontal or vertical plane as shown in Fig. N-184-5; provided that anangle of loading of five degrees or less from the vertical may be considered avertical angle of loading. (§1910.184(b))

Angulated roping [Powered platforms for building maintenance] means a suspension methodwhere the upper point of suspension is inboard from the attachments on the sus-pended unit, thus causing the suspended unit to bear against the face of the build-ing. (§1910.66(d))[Powered platforms for building maintenance/Existing installations(mandatory)] A system of platform suspension in which the upper wire ropesheaves or suspension points are closer to the plane of the building face than thecorresponding attachment points on the platform, thus causing the platform topress against the face of the building during its vertical travel. (§1910.66 App D)

Annealing The term "annealing" means heating then cooling to soften and renderless brittle. (§1910.265(b)(2))

ANSI means American National Standards Institute. (§§1910.66 App D, .179(a)(16),.180(a)(7), .181(a)(11); 1926.32(b))

Anthophyllite SEE “Tremolite, Anthophyllite, and Actinolite”Antirepeat means the part of the clutch/brake control system designed to limit the

press to a single stroke if the tripping means is held operated. Antirepeat requiresrelease of all tripping mechanisms before another stroke can be initiated. "Antire-peat" is also called single stroke reset or reset circuit. (§1910.211(d)(1))

API-ASME container A container constructed in accordance with the require-ments of §1910.110(b)(3)(iii).1 (§1910.110(a)(1))

1. Containers designed, constructed, and tested prior to July 1, 1961, according to theCode for Unfired Pressure Vessels for Petroleum Liquids and Gases, 1951 edition with1954 Addenda, of the American Petroleum Institute and the American Society ofMechanical Engineers, which is incorporated by reference as specified in §1910.6,shall be considered in conformance. Containers constructed according to API-ASMECode do not have to comply with section I or with App to section I. Paragraphs W-601to W-606 inclusive in the 1943 and earlier editions do not apply. (§1910.110(b)(3)(iii))

EXPLANATION OF SYMBOLS: Minimum Diameter of Curvature

Represents a contact surface which shall have a diameter of curvature atleast double the diameter of the rope from which the sling is made.

Represents a contact surface which shall have a diameter of curvature atleast 8 times the diameter of the rope.

Represents a load in a choker hitch and illustrates the rotary force on theload and/or the slippage of the rope in contact with the load. Diameter ofcurvature of load surface shall be at least double the diameter of the rope.

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