UVA, UVB, UPF, SPF...Key terms for understanding sun protection
UVA and UVB
The sun emits several types of rays, distinguished by their wavelength:
Extremely short wavelengths (X-rays, gamma rays, UVC), which are highly dangerous but luckily get absorbed in the upper layers of the atmosphere.
Very long wavelengths (radio waves), which are very weak at the Earth’s surface.
The main rays that reach us are:
Ultraviolet light, which includes UVA and UVB. These rays are invisible to the human eye and cannot be felt. UVB rays have shorter wavelengths and higher energy, whereas UVA rays have longer wavelengths and lower energy. Both UVA and UVB damage skin cells and contribute to skin cancer, premature skin aging, wrinkles, and brown spots. UVB rays are primarily responsible for sunburns, while UVA rays penetrate deeper into the skin due to their longer wavelengths, thus contributing more to skin aging.
Visible light, which we can see and which allows us to perceive shapes and colors.
Infrared light, which is invisible but heats solid and gaseous matter it encounters.
UPF
UPF (Ultraviolet Protection Factor) measures the level of sun protection provided by fabrics and indicates how much UV radiation the fabric absorbs and blocks. With a fabric rated UPF 5, 1/5 (20%) of the sun’s UV rays pass through the material. With a UPF 50+ fabric, fewer than 1/50 (2%) of the UV rays get through. Put another way, a UPF 50+ fabric blocks over 98% of UVA and UVB rays. UPF 50+ is the highest level of sun protection certification fabrics can achieve in Europe, under standard EN 13758-1. UPF 40, 45, 50, and 50+ are considered excellent levels of sun protection.
At Ker Sun, we only offer sun protective clothing certified UPF 50+ to ensure you receive the highest degree of protection.
SPF
SPF (Sun Protection Factor) is the sun protection rating for sunscreens and other sun protection creams. It ranges from 15 to 50 and indicates the percentage of UVB rays blocked by the sunscreen. A product with SPF 15 blocks about 95% of UVB rays, SPF 30 protects against about 96.7% of UVB rays, and SPF 50 blocks around 98.3% of UVB rays. For instance, a sunscreen with SPF 30 absorbs about 97% of UVB, leaving the remaining 3% to penetrate the skin.
Though often viewed by dermatologists as the final safeguard in sun protection, sunscreen remains an effective way to protect yourself from the sun’s harmful effects. However, it’s important to remember that sunscreen must be applied in sufficient quantity (to all areas of skin not covered by sun protective clothing) at least every two hours, and it does expire. Respecting the expiration date is necessary for effectively protecting your skin.
Sources:
