Official websites use. Share sensitive information only on official, secure websites. In the last decade, it has been proposed that the sun's IR-A wavelengths might be deleterious to human skin and that sunscreens, in addition to their desired effect to protect against UV-B and UV-A, should also protect against IR-A and perhaps even visible light. Unfortunately, the artificial NIR light sources used in such studies were not representative of the solar irradiance. Yet, little has been said about the other side of the coin.
IR-A might even precondition the skin — a process called photoprevention - from an evolutionary standpoint since exposure to early morning IR-A wavelengths in sunlight may ready the skin for the coming mid-day deleterious UVR. Consequently IR-A appears to be the solution, not the problem. It does more good than bad for the skin. It is essentially a question of intensity and how we can learn from the sun.
The spectrum of solar radiation reaching the Earth ranges from to more than 1,, nm and is divided as follows: 6. Infrared constitutes the waveband longer than nm and up to 1 mm. IR radiation can penetrate the epidermis, dermis, and subcutaneous tissue to differing extents depending on the exact wavelength range being studied.
Exposure to IR is perceived as heat [ 2 ]. Solar spectrum composition. Red X over UVC means they are blocked by the ozone layer. The strength of electromagnetic radiation depends on the energy of the individual particles or waves as well as the number of particles or waves present.
Electromagnetic radiation covers a spectrum with a wide range of photon energies that can also be expressed as a range of wavelengths. The spectrum has two major divisions:. Radiation that has insufficient energy to completely remove electrons from atoms and molecules is referred to as non-ionizing radiation. Examples of this kind of radiation are visible light, infrared, microwaves and radio waves. Radiation that falls within the ionizing radiation range has enough energy to remove tightly bound electrons from atoms, thus creating charged ions.
