Visible light falls within the range of 400 to 760nm, and wavelengths outside this range are invisible to humans. UV radiation has wavelengths less than 400nm, while IR has wavelengths greater than 760nm.
Welding arcs do not produce ionizing radiation, such as X-rays or Gamma rays, since the arc energies are too low to form such types of radiation.
Non-ionizing Radiation
Ultraviolet
Ultraviolet radiation (100-400nm) is divided into three bands, UV-A, 315-400nm, UV-B, 280-315nm, and UV-C, 100-280nm. It is generated by arc welding, cutting and gouging processes but not by fuel gas processes. The amount of UV radiation produced depends on the process, the shielding gas and the welding current being used.
Visible Light
Light that is visible to the human eye has wavelength between 400nm, the blue end of the visible spectrum and 760nm, the red end of the spectrum. High intensities of blue light, 400 to 500nm, have been shown to cause photochemical lesions on the retina.
Infrared
Both fuel gas and arc welding and cutting processes produce infrared radiation with wavelengths of 760nm and above.
Effects of Exposure
Ultraviolet
The skin and the eyes are the organs most at risk from the effects of exposure to UV radiation, and it is not only welders who are at risk, but other workers in the vicinity who may also be exposed to radiation from nearby welding or cutting activities.
Erythema is a photochemical response of the skin to UV-B and UV-C, and results in a reddening of the skin, as in sunburn
The most well known, and probably the most frequently suffered, effect from welding arcs is 'Arc eye' or 'welders flash' and this is caused by the action of UV-B and UV-C radiation on the outer eye.
Visible Light
Bright light, or glare, does not itself present a hazard to health, since discomfort occurs at a very small percentage of the illumination level required to cause damage, and the natural response is to close the eyes or shield them or turn away from the glare.
In visible light the major hazard is from blue light 400-500nm.
Infrared
The intense heat of IR from both electric arc and fuel gas processes can cause thermal burns to the skin and has the potential to cause eye damage in the form of retinal burns and cataracts.
Protection from Radiation
Skin
Standard work clothing, i.e. welders boiler suits, gloves and helmets, etc, will give adequate protection to skin from the effects of radiation from the welding operation.
Eyes
The best way of avoiding radiation damage to the eyes is NEVER to look at a welding arc without proper eye protection, however tempting that may be.
Normal glass spectacles and safety glasses give some protection from UV.
Lasers
Protection from lasers usually consists of protective clothing, gloves, and eyewear, plus barriers and micro-switches to prevent accidental entry when powered up.
First Aid
Minor skin burns from welding arc radiation to arms and face etc, which normally become apparent some time after exposure can be treated with proprietary sunburn creams. However, for more serious burns you should seek qualified medical advice as soon as possible.