Ultraviolet (UV) or ‘Black’ Lights are used extensively within NDT processes to produce fluorescence in the dyes and pigments contained within magnetic inks and fluorescent penetrants.
UV light is subdivided into three bands – UV(A), UV(B) and UV(C). It is the UV(A) which excites the fluorescent dyes and pigments and allows them to fluoresce.
It has long been known that UV(B) and UV(C) are associated with various detrimental health effects. Recent evidence suggests that UV(A) may also be involved.
Some individuals may also have an increased sensitivity to UV light and these people may suffer increased skin problems when exposed to this sort of light. It should be noted that the photosensitivity of an individual can be affected by cosmetics, drugs and other chemicals.
Although UV lights are safe in operation when used as intended, operators and users should minimise direct skin exposure to UV(A). This can easily be achieved by carrying out a few sensible precautions:
- Cover exposed skin with clothing giving good protection – examples are long sleeved overalls or loose clothing with a close weave. Wear gloves if possible.
- Apply sunblocks, or broadband sunscreens with high protection factors (≥ 15) to exposed or uncovered skin. Apply generously and reapply frequently.
- Never look directly at a UV light source and avoid looking at reflections from shiny surfaces. It is good practise to wear UV absorbing spectacles when working with UV light sources. These not only provide protection but also enhance contrast.