UVA is the long wavelength portion of the UV Spectrum. The UV spectrum is defined as the wavelengths twixt 100 and 400 nm with UVA usually defined as the wavelengths between 315 nm (nano meter) and 400 nm as depicted below.
UVA light is used in conjuntion with a Psoralen for phototherapy. The term then becomes PUVA (“P” UVA). This technology was very common but over the last ten years or so there has been a migration towards the use of UVB Narrowband which is generally considered to be the equal of PUVA but without the side effects. See http://www.uvbnarrowband.com/?p=41 for some info on the undesirable effects of PUVA.
UVA light is the main component of the light from a tanning bed. UVA without the use of a Psoralen to sensitize the skin does little for the treatment of most skin problems. UVA penetrates deeply and can cause premature aging of the skin while passing through the upper layers of the skin where the skin challenges such as Psoriasis, Vitiligo and Eczema reside.
UVA (PUVA) is becoming less and less popular as a treatment modality for most skin challenges.
One interesting application of UVA is its use at low energy levels as a “Woods Light” for skin inspection and forensic work. Many chemicals and DNA based materials fluoresce in the presence of UV light. The Wood’s Light was invented by Dr. Robert Woods early in the twentieth century.
.jpg)
