It’s the middle of the summer, and a lot of people are either working on their tans or showing them off. But what causes us to tan? And what are some dangers to tanning?

How do we tan?

Tanning is a result of exposure to UVA rays (recall that they are the ultraviolet rays that have the longest wavelength and the least amount of energy).

These rays go to the lower layer of the epidermis, where cells called melanocytes are activated. These cells produce melanin, which is a dark pigment that helps with UV protection. The production of this pigment is what causes the darkening, or tanning, of the skin.

Darker-skinned people actually have deeper tans than lighter-skinned people due to their melanocytes producing more melanin.

Dangers of tanning

UVA rays can also penetrate its way to your blood vessels and nerves, which can in turn damage your immune system. This damage makes it harder to recover from diseases and can lead to melanoma (a serious type of skin cancer). This is why intentional tanning is somewhat controversial. In fact, using tanning beds before the age of 35 can increase your risk of melanoma by 75%.

So careful with your browning, ladies and gents!


The Skin Cancer Foundation. 2013. International Study Links Tanning Beds to Melanoma. SkinCancer.org. <http://www.skincancer.org/news/tanning/iarc-tanning-link-study> August 01, 2013.