Skin damage isn't easily seen at the surface, but it's there, lurking just underneath. A special camera designed to show what the world looks like in ultraviolet, rather than visible, light, however, can show these subsurface freckles. In the video above Thomas Leveritt did just that, showing people on the street the subsurface damage their skin has wrought because of the sun's rays.
When your skin is exposed to the sun's ultraviolet radiation, the high-energy rays can damage your DNA and injure your cells. In the short term, that might just mean sunburn, but in the long term, it can lead to bigger problems, like skin cancer or an accelerated appearance of aging.
To help protect itself against damaging UV radiation, your body has a couple of defenses, including ramping up production of the skin pigment melanin. This is what gives you a tan, but prolonged UV exposure can also cause other types of skin damage, such as liver spots, solar lentigines, which look like extra potent freckles, or poikiloderma, which kind of looks like a rash.
According to dermatologist Brandith Irwin, some salons will use a similar camera technique to try to scare people into seeking treatment for this subsurface skin damage. But, for the most part, she says, there's nothing to be done to help.
Aside from the skin health aspect of all this, Leveritt's video is actually quite interesting for another reason. A number of animals, from bees to reindeer to salmon and others, can see ultraviolet light, which means their version of what humans looks like may be much more mottled than what we see.