UVA
UVA is a long wavelength ultraviolet ray from the sun. UVA rays
are the "aging" rays in the UV spectrum. UVA radiation
ranges from 320 to 400 nm in wavelength. Some wavelengths in that
range have greater potential to cause damage than other wavelengths.
UVA radiation is stronger in the early morning and late afternoon
when the sun's rays reach the Earth at an angle.
UVB
UVB is a medium wavelength ultraviolet ray from the sun. UVB rays
are the "burning" rays in the UV spectrum. UVB radiation
ranges from 280 to 320 nm in wavelength. Some wavelengths in that
range have greater potential to cause damage than other wavelengths.
UVB radiation is stronger between late morning and early afternoon
when the sun's rays are directed straight down at the Earth.
SPF
SPF stands for Sun Protection Factor. It is the ratio of UV radiation
dose required to produce recognizable redness on skin that has been
protected with a sunscreen from the UV radiation dose required to
produce the same redness on unprotected skin (using a clinical test
procedure on human skin). SPF tells you how much longer it will
take for your skin to begin to redden with the product on than if
your skin was unprotected. The percentage of burning UV rays that
a product blocks does not increase proportionally with the SPF value.
So SPF values indicate a function of skin reddening.
UPF
UPF stands for Ultraviolet Protection Factor. It is the ratio of
the average effective ultraviolet radiation (UVR) irradiance transmitted
and calculated through air to the average effective UVR irradiance
transmitted and calculated through fabric. In other words, it is
the amount of ultraviolet radiation that a fabric blocks. Hence
UPF values are used in the Fabric's UV transmittance test by spectrophotometer
equipment.
Sun protective clothing
Sun-protective clothing is any garment that can provide adequate
protection from the sun. Generally speaking, clothing must have
a UPF value of 15 to 50+ (blocks 93 - 98% of UV radiation), and
cover or shade sufficient skin to protect a person from the damaging
rays of the sun.
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