Ultraviolet (UV) rays are generally categorized into UVA and UVB:
▶️ UVA has longer wavelengths and can penetrate the skin, causing damage to collagen, leading to skin aging, and tanning.
▶️ UVB has shorter wavelengths and higher energy, resulting in sunburn and skin damage.
⚪PA (Protection Grade of UVA rays) is a system commonly used in Japan, indicating the level of protection against UVA rays. It is usually denoted with a “+” sign.
The more “+” signs, the longer the protection. The highest rating is PA++++, signifying the highest protection against UVA rays.
⚪SPF (Sun Protection Factor) is a measure of protection against UVB rays. It indicates how much longer the skin can be exposed to the sun without getting
sunburned compared to not using sunscreen. SPF values can go up to 50, with anything over 50 often represented as 50+.
For example, products with higher SPF values provide longer protection against sunburn.
⚪PPD (Persistent Pigment Darkening) is a system used in Europe, representing the “persistent tanning” factor. It is convertible to the PA system:
◼️ PPD 2-4 corresponds to PA+
◼️ PPD 4-8 corresponds to PA++
◼️ PPD 8-16 corresponds to PA+++
◼️ PPD 16 and above correspond to PA++++