Science Questions

Why do you go red when sunburnt?

I’ve heard on one of your podcasts about sunburn and the damage it imparts but I was wondering what’s the actual cause of the redness in sunburn. What specific damage to the skin causes the redness that remains over days after the initial UV exposure? What are we seeing that’s happening at the molecular level that’s red? Michael Stevens

Chris and Kat discussed this question on the show...

Kat: What’s happening is inflammation. When you get sunburn the ultraviolet rays from the sun come in, damage the DNA in your skin. If they damage it really severely then your skin cells will die in order to protect you from cancer because your DNA’s damaged. Dying cells attract the immune system. They attract immune cells like macrophages that have to come in and eat up the dead cells. That encourages inflammation so you’ve got all these molecules called cytokines being produced. You’ve got inflammation redness, you may notice swelling as well if you get really sunburned. That’s what’s going on.

Chris: Would anti-inflammatories like aspirin make you feel better if you’ve got sunburn?

Kat: They’re help to relive the pain and they may help to take the inflammation down but of course the most sensible thing is don’t get sunburnt in the first place.

Chris: What about sunbeds? I was reading a statistic the other day. It’s a totally unregulated industry. In one case there was a set of sunbeds where the UV was five times stronger than you’d get from the noonday sun on an Australian beach.

Kat: I know and that’s a very interesting issue. In Scotland this week, in the Parliament there they’re having a debate about whether the sunbed industry should be regulated and particularly whether the sunbed should be banned for people under 18 because at that age your skin is very sensitive to this kind of damage from the sunlight and also from the ultraviolet radiation in sunbeds. At the moment, particularly in the UK sunbeds are pretty much unregulated. There’s a voluntary code of conduct from the sunbed association that parlours can sign up to but it’s not compulsory.

Chris: So they could be harmful. You could actually be doing yourself a lot of damage because, how much have they been standardised: what dose you’re getting and what it’s doing to you?

Kat: Absolutely, we would recommend people to steer clear of sunbeds generally. Especially using them excessively and do watch out because they are damaging your skin and if you overdo it you are increasing your risk of skin cancer.

Chris: And you will end up looking like a prune.

January 2008