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Selected Glossary of Human Factors and Safety Terms


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Accident. An unintentional event resulting in fatality, injury, illness, or property damage.

ANSI. American National Standards Institute. A private, non-profit organization that administers and coordinates voluntary industry standards in the United States. ANSI standards have been developed for equipment such as safety goggles, helmets, power tools, elevating work platforms, and roadway lighting equipment [ANSI Web site].

Anthropometry. The technology of measuring human physical traits such as size, reach, mobility, and strength.

ASTM. American Society for Testing and Materials. A private, non-profit organization that provides an international forum for the development and publication of voluntary consensus standards for materials, products, systems, and services. ASTM standards include those for test methods for determining slip-resistance, design and construction guidelines for safe walking surfaces, design and installation of grab bars, and design and manufacture of amusement park rides [ASTM Web site].

Attention. Direction and concentration of cognitive resources. "Divided attention" occurs in situations in which two or more separate tasks or mental operations must be attended simultaneously, for example, looking for road signs and scanning traffic while steering a vehicle. "Focused attention" occurs in situations in which one information source must be attended to the exclusion of others, for example trying to find a particular road sign in a group of road signs. "Selective attention" occurs in situations in which one source of information is inappropriately monitored to the exclusion of other relevant information sources, such as being so engrossed in talking on a cell phone that a driver misses his freeway exit.

Balance. A state of bodily equilibrium.

Barrier guard In machine guarding terminology, a rigid shield or device that covers hazard points on a machine to prevent accidental and injurious contact with body parts, or to control hazardous ejection and emissions from the machine such as flying chips, air contaminants and noise. Syn. Machine guard.

Biomechanics. A discipline that studies various aspects of physical movements of the body and body members.

Boom. A long pivoting structure or arm that extends from an upright to lift or carry something, such as on a crane or backhoe.

Brightness. The subjective attribute of light intensity in which brightness implies higher light intensities and dimness implies lower light intensities.

CAL-OSHA. California Division of Occupational Safety and Health. (See OSHA) [Cal-OSHA Web site].

Candela. Abbr. cd. A unit of luminous intensity equal to 1/60 of the luminous intensity per square centimeter of a blackbody radiating at the solidification temperature of platinum. Also called "candle" or "standard candle" or "new candle".

cd. Candela.

Coefficient of friction. The ratio of the friction force between two objects and the force pressing the objects together. "Static coefficient of friction" is the ratio of the hoizontal force needed to initiate a slipping action of an object along a surface, and the vertical force on the surface. "Dynamic coefficient of friction" is the ratio of the horizontal force needed to continue a slipping action of an object along a surface, and the vertical force on the surface. A higher coefficient indicates greater surface traction.

Cone. In eye physiology, a cone-shaped photoreceptor in the retina of the eye responsible for fine visual acuity and color vision. Cones function only at daylight levels of illumination.

Contaminant. An undesirable liquid or solid material on a walkway surface. Contaminants pose slip and trip hazards.

Contrast. The difference in luminance between two areas.

Contrast ratio. A mathematical expression describing the difference in luminance between two areas; the contrast ratio can be expressed as L1/L2 or as (L2L1)/L2, where L1 is the luminance of the first area and L2 is the luminance of the second area.

Control. In human-machine interaction, a mechanism for regulating or guiding the operation of a tool, apparatus, machine or other system; examples include push button, switch, knob, wheel, lever, and pedal.

Dark adaptation. The physical and chemical adjustments of the eye and visual system that make vision possible in low levels of illumination by increasing its sensitivity to light.

dB. Decibel.

Decibel. A measure of sound intensity.

Display. Any method of presenting information, such as a highway sign, warning buzzer or TV monitor.

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