When the sun insolates, ray meets UVA stimulate the generation of melanin long-term and abidingly directly, cause skin pigment ad cool-headed, bring about the skin to blacken, make splash.

• 太阳暴晒时，UVA射线会长期持久地直接刺激黑色素的产生，引起皮肤色素沉着，导致皮肤变黑、生成色斑。