The harmful effects of ultraviolet (UV) light on the skin are well-known, but the specific impact of UVA1 radiation deserves special attention. Within the solar UV spectrum, UVA1 wavelengths stand out as the longest and most constant throughout the year, with the ability to deeply penetrate all layers of the skin. This results in a range of detrimental effects that are mediated by various internal components, primarily involving the generation of reactive oxygen species (ROS).

The oxidative stress caused by UVA1 radiation triggers a cascade of molecular changes, including lipid peroxidation, protein carbonylation, DNA damage and subsequent signaling within cells. These alterations lead to mutations, apoptosis (cell death), dermis remodeling, inflammation and abnormal immune responses.

Such biological disruptions contribute to various clinical consequences, including hyperpigmentation, inflammation, sun allergies, weakened immune response, premature aging (photoaging) and an increased risk of developing skin cancers. It is worth noting that even the use of UVA1 phototherapy or tanning beds can induce these harmful impacts. Furthermore, external factors like pollutants and visible light (Vis) have been found to independently and synergistically intensify the effects of UVA1 radiation. This means that combined exposure to UVA1 rays along with pollutants or Vis can lead to even greater damage to the skin.

Given the significant biological and clinical implications of UVA1 radiation, as well as its prevalence in solar UV radiation, it becomes imperative to adopt broad-spectrum photoprotection measures that encompass UVA1 up to 400 nm. This is crucial to prevent both short-term and long-term consequences of sun exposure on the skin, regardless of an individuals skin type. Moreover, considering the cumulative and synergistic effects of UVA1 with pollution or Vis, it is essential to provide protection beyond 340 nm to effectively shield against solar damage associated with all wavelengths, including UVA1 and Vis.

In summary, an in-depth review of the biological, cellular and clinical repercussions of UVA1 radiation, coupled with its prominence in solar UV radiation, underscores the necessity for comprehensive protection against UVA1 rays. Daily photoprotection, encompassing a broad range of wavelengths, is crucial to safeguard skin health and minimize the detrimental effects of sun exposure. Additionally, addressing the cumulative effects of UVA1 with pollution and Vis through adequate filtration measures is indispensable for comprehensive and effective solar protection.

Source: Bernerd F, Passeron T, Castiel I, Marionnet C. The damaging effects of long UVA (UVA1) rays: a major challenge to preserve skin health and integrity. Int J Mol Sci. 2022; 23(15):8243.