What wavelengths does sunscreen block?

Sunscreen primarily blocks ultraviolet (UV) radiation, specifically UVA and UVB rays. UVA rays can penetrate deeply into the skin, causing aging and long-term skin damage, while UVB rays are responsible for sunburn and play a key role in developing skin cancer. Many sunscreens are formulated to block both types of UV radiation, with SPF (Sun Protection Factor) indicating their effectiveness against UVB rays, while broad-spectrum formulations also protect against UVA rays.