When you buy back a bottle of sunscreen, you can definitely see various indexes on the packaging. What is the real meaning of these common indexes?
UVA long-wave ultraviolet, it is the main reason for premature skin aging. It can penetrate the dermis layer, make the skin tan, even skin cancer, the effect is slow and long-lasting, and it is cumulative. Not blocked by windows, umbrellas, etc., even if it rains on a cloudy day.
UVB is a medium-wave ultraviolet, which can reach the dermis and cause sunburn. It causes skin peeling, erythema, sunburn, etc., but it can be blocked by glass, umbrellas, clothes, etc.
PA is an index that indicates how much UVA damage is prevented. At present, the standards adopted by sunscreen products on the market can be divided into three types: PA+ (effective), PA++ (very effective), and PA+++ (very effective). Products that are not marked with PA may not have UVA protection.
SPF mainly refers to the degree of protection against UVB. For Asians, the general skin will appear to be red in 15 minutes in the sun. SPF10 means that using this product can isolate ultraviolet rays for 15 minutes×10 times = 150 minutes, and so on.