The optimal wavelength range for sunscreen agents to effectively absorb UV radiation is between 290 and 400 nanometers nm . This range encompasses both UVA 320-400 nm and UVB 290-320 nm radiation, which are the primary types of ultraviolet radiation that contribute to skin damage from sun exposure.UVB radiation is responsible for causing sunburns, DNA damage, and plays a key role in the development of skin cancer. UVA radiation, while less intense than UVB, penetrates deeper into the skin and can cause long-term damage, such as premature aging, DNA damage, and also contributes to skin cancer risk. Therefore, an effective sunscreen should provide broad-spectrum protection, meaning it should absorb both UVA and UVB radiation.The effectiveness of a sunscreen in preventing skin damage from sun exposure is measured by its Sun Protection Factor SPF . SPF is a measure of how well a sunscreen protects against UVB radiation. For example, an SPF 30 sunscreen allows 1/30th of the UVB radiation to reach the skin, providing approximately 97% protection. However, it is important to note that no sunscreen can block 100% of UV radiation.In addition to SPF, the effectiveness of a sunscreen also depends on its ability to absorb UVA radiation. This is often indicated by a UVA protection rating system, such as the PA system with ratings like PA+, PA++, and PA+++ , or the UVA circle logo in Europe.In summary, the optimal wavelength range for sunscreen agents to effectively absorb UV radiation is between 290 and 400 nm, covering both UVA and UVB radiation. The effectiveness of a sunscreen in preventing skin damage from sun exposure is determined by its SPF value and its ability to provide broad-spectrum protection against both UVA and UVB radiation.