The Science Behind a Sunburn

One of the things that students look forward to most during the winter semester is the sunshine over spring and summer break.

After being cooped up studying all school year, many students can’t wait to get outside and go swimming, hiking, sunbathing, or basically anything else in the summer sun; however, sun damage has long-lasting effects on the body.

There are three types of ultraviolet radiation the sun emits that hit Earth: Ultra-violet A, B and C (UVA, UVB, and UVC). UVC radiation doesn’t lead to skin cancer (the rays can’t penetrate the ozone), but both UVA and UVB must be protected against for healthy skin.

UVA rays are longer wavelengths (320-400 nm) and make up 95 percent of solar UV radiation that makes it to Earth. UVA is responsible for most of the long-lasting sun damage as it can penetrate deep into the dermis. It is responsible for aging, wrinkles, skin cancer, and genetic damage. Unfortunately, even if it is cloudy and the sun isn’t visible, these UVA rays can affect your skin. These rays are much more prevalent than UVB rays, but they are less intense.

UVB rays are the mid-range wavelengths (290-320 nm). This wavelength burns, tans, and ages skin. UVB hits most heavily from 10:00 a.m. to 4:00 p.m. in April through October, especially on a cloudless day. Interestingly enough, these rays don’t penetrate glass.

Most sunscreens do not protect against UVA rays. When a sunscreen’s label says that it has an SPF rating of 15, 30, etc., it is in relation to UVB rays. For the best protection, make sure to buy a sunscreen that says it has multispectrum or broad-spectrum protection. These sunscreens are sensitive to both UVA and UVB rays.

Sunscreens have organic and inorganic ingredients. Most sunscreens have a mix of both elements. Organic ingredients act as absorbers against UV rays and inorganic ingredients act as blockers and deflectors of UV rays. These two elements go a long way towards protecting the skin from UV.


-Mackenzie Brown, College of Physical and Mathematical Sciences


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