Ultraviolet B photon and short-wave Ultraviolet A photon (UVB and short-wave UVA)

UVB and short-wave UVA photons are forms of ultraviolet electromagnetic radiation with wavelengths ranging from 280–320 nm (UVB) and 320–340 nm (short-wave UVA, also called UVA2)[3][7][8]. While neither is a molecule or classical therapeutic target, both penetrate the skin to different depths and trigger diverse biological effects. UVB photons have higher energy and are primarily absorbed in the epidermis, causing direct DNA damage (notably cyclobutane pyrimidine dimers and 6-4 photoproducts), leading to sunburn, immunosuppression, and increased risk of skin cancer[2][4][7]. Short-wave UVA photons penetrate deeper into the dermis, generating reactive oxygen species that induce oxidative stress, collagen breakdown, photoaging, and potentially indirect DNA damage[2][3][8]. Both types of UV irradiation can activate neuroendocrine and immune responses, and their systemic effects may extend beyond the skin to involve hormonal and nervous system regulation[1][5]. The medical relevance of these photons primarily concerns understanding their contribution to skin disease and systemic health via environmental exposure, rather than as candidates for drug targeting.

Other names

Ultraviolet B radiationUVBShort-wave ultraviolet A radiationUVA2 (320–340 nm)UVB (280–320 nm)