All electromagnetic radiation, including UV rays, increase in energy as the wavelength gets shorter. UV rays exist through a range of wavelengths from 100nm to 400nm, shorter than visible light which exists from 400nm to 700nm range. UV rays that have wavelengths closer to the visible light end of spectrum, (sometimes referred to as ‘near UV’) have less energy to cause damage than UV rays further away . To help classify the difference, scientists have divided the UV range into three bands
UVA-315-400 nm – The most penetrating band of UV, but with the least energy to cause damage. Accounts for 98% of UV radiation reaching the earth’s surface. Causes tanning and can initiate skin cancers with prolonged exposure.
UVB – 280-315 nm – The most damaging band of UV to humans. Accounts for 2% of UV radiation reaching the earths surface. Causes sunburn and skin cancer.
UVC – 100-280 nm- The most potentially damaging band of UV. Fortunately this band is easily blocked by the earths atmospheres and doesn’t reach the surface.