Everyone is exposed to ultraviolet radiation from the sun. The sun emits electromagnetic radiation of different wavelengths. Some radiation is visible to the human eye, such as the radiation that makes up the colors of the rainbow.

However, ultraviolet light is an invisible radiation beyond the violet end of visible light.

Ultraviolet (UV) light, also known as electromagnetic radiation, can be divided into three bands: UVA, UVB, and UVC according to the wavelength.

UVC has the shortest wavelength (100-280nm), almost 0 UVC radiation can reach the surface of the earth, because all UVC is absorbed by the atmosphere
UVB radiation is slightly longer than UVC (280-315nm), and approximately 90% of UVB is absorbed by the atmosphere; therefore, the radiation reaching the earth's surface contains less than 2% of UVB.
UVA has the longest wavelength (315-400nm), and more than 98% of the radiation reaching the surface of the earth is UVA because it is less affected by the atmosphere.

Click here for more information on the Hong Kong Observatory website.

Ultraviolet light may be applicable to many different fields, such as medical, business and daily life. UVA and UVB are commonly used in medical applications such as the treatment of different diseases and environmental sterilization. In addition, UVA can effectively control pests and check counterfeit banknotes.

Generally, UVC can be used to disinfect water and disinfect the surface of objects. For example, some companies in the world are installing UVC lamps for refrigerators in supermarkets to store food in a sterile environment, thereby reducing food waste and saving a lot of costs. UVC is also suitable for our daily life, and is used to disinfect the surfaces of mobile phones, keys, glasses and other objects.

Click to learn more about portable UV sterilizers for belongings.