Human skin exposure to ultraviolet radiation (UVR) from sunlight can cause many adverse effects. Therefore, it becomes necessary to protect the skin from damaging UVR through various means, one of which is through adequate application of sunscreen, especially when exposed to sunlight for prolonged periods of time. Ultraviolet (UV) light that reaches the surface of the Earth includes both UVB (290–320 nm) and UVA (320–400 nm). UVB is mainly responsible for redness or sunburn. SPF is a measure of protection from UVB light . UVA rays are not directly absorbed by biological targets but they can still dramatically impair cell and tissue functions. UVA penetrates deeper into the skin than UVB. This particularly affects connective tissue, inducing the production of detrimental reactive oxygen species (ROS) which in turn damage DNA, cells, vessels, and tissues. It is important to note that under all weather conditions, the UVA irradiance is at least 17 times higher than the UVB irra...
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