What is the main effect of UVB light?

The main effect of UVB light is that it causes skin burning. UVB rays are a type of ultraviolet radiation emitted by the sun that primarily affects the outer layers of the skin. When skin is exposed to UVB radiation, it can lead to inflammation and damage, resulting in sunburn. This type of light is known for its role in the development of erythema (redness of the skin) and can also contribute to long-term skin damage, including an increased risk of skin cancer.

Other options do not accurately describe the main effect of UVB light. For instance, while UVB light can lead to tanning, it does not cause immediate tanning as that is predominantly due to UVA rays and the skin’s production of melanin in response to sun exposure. UVB rays do not penetrate deeply into the skin; that characteristic is more associated with UVA rays, which can reach deeper skin layers and affect collagen and elastin. Lastly, while some benefits, including skin rejuvenation, can be associated with certain types of UV light exposure (specifically in controlled settings using low-intensity UV light), UVB light's primary role in skin exposure is the negative effect of burns, making it less relevant for rejuvenation purposes in a general context.