UV Radiation and Skin Health

UV Radiation and Health

• UV radiation represents 5% of the total solar radiation reaching the Earth's surface
• 95% of UV radiation reaching the Earth's surface is UVA, with a small 5% UVB component
• UVC radiation is blocked out by the ozone layer, while UVB radiation is mainly absorbed by the atmosphere

Effects of UV Radiation on Skin

• UVB radiation is the major cause of sunburn, which is acute skin damage perceived as redness
• UVB radiation is a leading factor in the development of skin cancer
• UVA radiation penetrates deeper into the skin, down to the dermis
• UV radiation can be divided into three categories based on wavelength, with shorter wavelengths being more harmful but less able to penetrate the skin

Sunscreens and After-Sun Products

• SPF is a measure that indicates how long it takes for UV rays to redden protected skin compared to unprotected skin
• Broad-spectrum protection refers to protection against both UVA and UVB rays
• Sunscreens are considered OTC drugs in the US, while after-sun products are considered cosmetics
• Quality-related issues of sunscreens and after-sun products include valve clogging, separation of emulsions, microbiological contamination, clumping, and rancidification
• Parameters commonly tested by cosmetic companies to evaluate the quality of their sunscreens include spray characteristics, aerosol can leakage, and actuation force

Performance of Sunscreens

• The most frequently tested parameters referring to the performance of sunscreens include the SPF value, water resistance, and broad-spectrum protection