The most important thing to worry about when concerning yourself with the levels of light or sunlight to which you are exposed are the possibly permanent hazards that UV can cause to both your eyes and your skin.

UV light contains a lot of hazards that we must be sure to keep under control.

UVC light

UVC light is the worst kind of light. UVC will damage living cells quickly with painful, burning effects. However it is a less penetrating kind of light because it is easily absorbed into the skin. Our epidermis, the outer layer of skin containing mostly dead skin cells, will provide extra protection from the damages UVC lights may cause, especially if the UVC rays are emitted in shorter wavelengths, of course. But you should not count on your epidermis to protect you, it can only protect you somewhat.

UVC lights with particularly short waves are commonly used to kill germs.

UVB light

UVB light is far worse than UVA light, it irritates the skin although the skin is equipped to handle small amounts of UVB and recover on its own. Nonetheless, unless a doctor has recommended that you do so for medical reasons, you should always try to avoid any exposure to UVB light for any extended amount of time.

UVA light

There are UVA wavelengths in some kinds of lights that are basically harmless to the skin and eyes. These, the safer UVA wavelengths usually come from blacklights and general-purpose high-pressure mercury lamps. Nonetheless, the hazard is not a total zero. Even with these types of lampsthey still have a bit of risk about them that you should be aware of if you use them.

The same hazard applies to any light containing UV that passes through plain glass. With the exception of some lights that use some kind of drugs to photosensitize skin into much less harmful amounts of wavelengths of UV light emitted. It is highly recommended that you check with your doctor if you are concerned about harmful lighting in your home, office, theatre, school, or wherever.

Tanning beds use lights with shorter UVA wavelengths, and many people believe that any sun tanning is not completely safe for anyone no matter how you approach it. Among the harmful effects of strong UV light are skin cancer and an appearance of accelerated aging of the skin.