Inorganic filters are physical ingredients that scatter or reflect UVR away from the skin.
The Inorganic filter ingredients in sunscreen are zinc oxide and titanium dioxide, (tiny particles of metal-based ingredients, Nanoparticles).
Inorganic filters are able to block both UVA and UVB
Nanoparticles range from 1 to 100 nanometres in size, a nanometre is one millionth of a millimetre, which are invisible to the human eye.
We are exposed to nanoscale particles in the environment in the form of smoke, dust, ash and fine clays through the air, food, and water. Foods are also naturally composed of nanoscale components.
Zinc oxide and titanium dioxide were the first ingredients to be used in Australian sunscreens in nanoparticle form; however, other ingredients may be used in nanoparticle form if they have been specifically evaluated and approved by the TGA.