James A. Hathaway and David H. Sliney

Visible light is generally defined as that portion of the electromagnetic spectrum between approximately 380–400 nm and approximately 760 nm.1 Some reference sources list the upper limit of the visible light band as 780 or 800 nm.2,3 Within the visible light spectrum, blue light (400–500 nm) is of particular importance. Infrared radiation is divided into the following three bands: IR-A is between 760 and 1400 nm, IR-B is between 1.4 µm (1400 nm) and 3 µm, and IR-C is between 3 and 1000 µm (1 mm). This ABC notation is sometimes referred to as near, middle, and far IR.


Visible light, along with the adjacent portions of the ultraviolet and infrared bands of radiation, makes up much of the solar radiation reaching the surface of the Earth. Outdoor occupations naturally have greater exposure to visible light and IR radiation. Visible light reflecting off sand and snow can create hazardous conditions that require eye protection. Ambient IR radiation can contribute to heat load, particularly in persons who work outdoors while wearing impervious clothing. Issues related to heat stress are covered in Chapter 6. Man-made sources of broad-spectrum intense visible light include arc welding or cutting, arc lamps, spotlights, gas and vapor discharge tubes, flash lamps, open flames, and explosions.4 Even though ultraviolet radiation is the main concern with many of these exposures, ...

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