Ultraviolet B and Ultraviolet A radiation (UVB/UVA)

Ultraviolet B (UVB) and Ultraviolet A (UVA) radiation are segments of the electromagnetic spectrum emitted by the sun and artificial sources that significantly impact human health (WHO, 2023). UVB (280–315 nm) is the primary cause of direct DNA damage, leading to the formation of cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts, which are precursors to skin cancer (IARC, 2012). UVA (315–400 nm) penetrates deeper into the dermis, where it generates reactive oxygen species (ROS) that cause indirect oxidative damage to DNA and structural proteins like collagen, driving the process of photoaging (PubMed, PMID: 18248499). While these are physical agents rather than biological molecules or receptors, they are the primary targets for photoprotective agents such as sunscreens. Sunscreens, including physical blockers like Zinc oxide and chemical absorbers like Avobenzone, work by reflecting or absorbing these photons to prevent their interaction with cellular chromophores (FDA, 2021). Additionally, UV radiation is utilized therapeutically in controlled doses for treating dermatological conditions like psoriasis and vitiligo, though chronic exposure remains a major risk factor for melanoma and keratinocyte carcinomas (Skin Cancer Foundation, 2022).

Other names

UV radiationSolar radiationActinic radiationUltraviolet light

Physical or chemical absorption, reflection, or scattering of ultraviolet photons to prevent their penetration into the skin and subsequent interaction with biological chromophores such as DNA (FDA, 2021).