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Subchapter 7. General Industry Safety Orders
Group 16. Control of Hazardous Substances
Article 107. Dusts, Fumes, Mists, Vapors and Gases
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§5140. Definitions.

As used in Article 107:

Abrasive-blasting respirator. A continuous flow supplied-air respirator constructed so that it will cover the wearer's head, neck, and shoulders to protect him from airborne dust and rebounding abrasive.

Abrasive wheels. An abrasive wheel is a power-driven wheel consisting of abrasive particles held together by artificial or natural, mineral or organic bonds. Metal, wooden, cloth or paper wheels or discs having a layer or layers of abrasive on the surface are not included. Natural sandstones (quarried) are not included.

Administrative control. Any procedure which limits exposure by adjustment of the work schedule.

Blast-cleaning enclosures. These include rotary blast cleaning tables, blast cleaning barrels and drums, abrasive blasting cabinets, blast cleaning rooms, abrasive separators, and similar enclosures. In blast cleaning rooms the operator works inside to operate the blasting nozzle; at blasting cabinets the operator directs the nozzle through openings in the cabinets. In other types of enclosures operation is automatic.

Branch duct. The part of an exhaust system piping or ductwork that is connected directly to the hood or enclosure.

Duct. Any pipe, flume, or channel, forming a part of a ventilating system, used to convey air, dusts, fumes, mists, vapors or gases.

Dust. Particles of solid matter, other than fumes, in such a state of comminution that they may be inhaled.

Engineering controls. Methods of controlling occupational exposure to injurious materials or conditions by means of general or local exhaust ventilation, substitution by a less hazardous material, by process modification, or by isolation or enclosure of health hazard-producing operations or machinery.

Exhaust purifier device. It is given a broad interpretation as any reliable and identifiable appliance added to an internal combustion engine to reduce toxic exhaust products. Special fuel additives may be certified as part of a device provided that other toxic components of exhaust are not increased significantly.

Exhaust system. A complete suction installation including all hoods, ducts, fans, jets, separators, and receptacles when required, and any other part necessary for the proper installation and operation thereof.

Fan. A rotary machine which creates the movement of air in the exhaust or ventilation system.

Fumes. Solid particles generated by condensation from the gaseous state, generally after volatilization from molten metals, etc., and often accompanied by a chemical reaction such as oxidation.

Gas. An aeriform fluid.

General ventilation. That type of ventilation which provides for general movement of air throughout rooms or buildings by either a gravity system or a mechanical system.

Gravity system of ventilation. One which depends wholly upon relative air density.

Harmful exposure. An exposure to dusts, fumes, mists, vapors, or gases:

(a) In excess of any permissible limit prescribed by Section 5155; or

(b) Of such a nature by inhalation as to result in, or have a probability to result in, injury, illness, disease, impairment, or loss of function.

Hazard. A source of risk, danger, or peril capable of causing injury. As used in Article 107, this meaning refers to dusts, fumes, mists, vapors, gases or chemicals capable of producing adverse health effects.

Hood. A shaped inlet designed to capture contaminated air and conduct it into the exhaust duct system.

Isolated operation. One which is carried on in a location where, or at such time that, no employee except those actually engaged in the operation involved is exposed to the hazards resulting therefrom.

Local exhaust ventilation. A mechanical ventilation system in which a hood is located at or near the point of release of dusts, fumes, mists, vapors or gases.

Main duct. A pipe or duct into which one or more branch ducts enter and which connects such branch ducts to the remainder of the exhaust system.

Mechanical ventilation system. One which depends upon power-driven equipment for its operation.

Mists. Suspended liquid droplets generated by condensation from gaseous to liquid state or by breaking up a liquid into a dispersed state, as by splashing, foaming, or atomizing.

Pitot traverse. The measurement of the air velocity in a duct using a pitot tube at several points in order to obtain an accurate average value of air velocity in the duct.

NOTE: The number of points to be measured depends on the size and shape of the duct. For guidance see Industrial Ventilation, 13th Ed. (1974), American Conference of Governmental Industrial Hygienists.

Separator/collector. The part of the exhaust system in which entrained material is separated from the air which conveys it.

Spray booth or Room. A power-ventilated structure provided to enclose or accommodate a spraying operation, to confine and limit the escape of spray, vapor and residue, and to safely conduct or direct them to an exhaust system.

Toxic material. A material in concentration or amount which exceeds the applicable limit established by a standard, such as Sections 5155, 5208, and 5209 or, in the absence of an applicable standard, which has the capacity to produce personal injury or illness to persons through ingestion, inhalation, or absorption through any body surface.

Vapor. The gaseous form of a substance normally liquid or solid.(Title 24, T8-5140)

NOTE: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.


1. Repealer and new section filed 7-18-75; effective thirtieth day thereafter (Register 75, No. 29).

2. Amendment filed 7-16-76; effective thirtieth day thereafter (Register 76, No. 29).

3. Amendment filed 7-27-77; effective thirtieth day thereafter (Register 77, No. 31).

4. Amendment of definition "Harmful Exposure" filed 5-25-79; effective thirtieth day thereafter (Register 79, No. 21).

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