Sunscreen Safety

Photo by Sujin Jetkasettakorn

Summer is here and we all love to spend time outdoors. Some sunshine is good for us, we all need Vitamin D. But how much is too much? And how do we protect ourselves with safely and effectively? To select the best sunscreens, first we should understand the sun's radiation. There are two types of ultraviolet radiation we need to protect our skin from, UVA and UVB.


What's the difference between UVA and UVB?
UVA is ultraviolet radiation between 400-320nm wavelength and UVB is between 320-290nm wavelength. The shorter the wavelength, the higher the energy of radiation. UVA rays account for 90 to 95% of UV radiation that reaches the earth. While UVB makes up only 5-10% of solar radiation, its high energy damages surface epidermal layers and causes sunburn. UVB is strongest between 10AM and 4PM, from April to October and do not significantly penetrate glass. UVA is present equally throughout the daylight hours and throughout the seasons, and can penetrate cloud and glass. UVA penetrates deeper layers of skin and causes tanning. However, both types of UV rays can cause skin cancer because they damage skin cells and alter their DNA. Both types of rays also contribute to premature aging of skin.