ultraviolet sunlight (and sunscreens)
Last reviewed 07/2021
To choose the correct sunscreen, one must be aware of the nature of the damaging agent: ultraviolet - UV - radiation. UV rays are classified into three groups:
- UVA - wavelength 320-400nm; accounts for 90% of the total
- UVB - wavelength 290-320nm; higher energy rays which are by far the most damaging
- UVC - wavelength 200-290nm; filtered out by the ozone layer
Sunscreens mainly work by blocking ultraviolet B wavelengths which are primarily responsible for sunburn. There is however now evidence that ultraviolet A can also damage the skin. Now most sunscreens available in the UK have good ultraviolet A blocking agents in addition to ultraviolet B blocking agents.