Neon Beach

UVA is found in the region between 320 and 400 nm and is the least powerful wavelength band of UV radiation. UVA acts primarily to cause the melanin pigments in the skin to oxidize (darken) creating the cosmetic tan and has limited power to cause erythema.
UVB is found in the region between 280 and 320 nm. It comprises the wavelengths primarily associated with erythema (sunburn), is also necessary for the production of vitamin D in the skin and is primarily responsible for stimulating increased melanin production. UVB wavelengths (at 305 nm) have 1,000 times more erythemal power than UVA wavelengths.
UVC is found in the region between approximately 200-280 nm and is called germicidal UV because of its proven effectiveness in killing sing-cell organisms. Solar radiation in the UVC range is absorbed almost entirely by the atmosphere and that is fortunate considering that even a short overexposure to UVC is very harmful to the eyes and causes severe erythema (sunburn). One place where radiation in the UVC range can be found is in the arc of a welding torch. For that reason, optical damage referred to as "welders eye" is caused by UVC light. It should be noted that UVC wavelengths are not produced by the UVR sources utilized by the indoor tanning industry