What is the primary effect of UVB rays on the skin?

The primary effect of UVB rays on the skin is immediate skin burning. UVB rays are the shorter wavelength portion of ultraviolet radiation, and they primarily affect the outer layer of the skin (the epidermis). When the skin is exposed to UVB radiation, it can lead to sunburn, characterized by redness, pain, and inflammation. This reaction occurs fairly quickly after exposure, often within a few hours.

In contrast, the other options pertain to different effects or types of ultraviolet radiation. Long-term skin aging is primarily associated with UVA rays, which penetrate deeper into the skin and contribute to the breakdown of collagen and elastin, leading to wrinkles and sagging over time. Deep dermal penetration is also characteristic of UVA rays, as they can reach deeper layers of the skin compared to UVB. Ulcer formation is not typically associated with UV radiation but rather with other skin conditions or irritants. Therefore, the correct understanding of UVB's immediate effects helps differentiate it from the effects of other types of UV radiation.