How does sunscreen work?

Sunscreen is made up of a mixture of organic and inorganic particles to protect your body from potentially harmful UV radiation. The sunlight is made up of various different types of UV radiation; these include UVA, UVB and UVC radiation. Each of these types of UV radiation is of different wavelength which makes the sunscreen easier or harder to protect your skin from burning. For example UVC radiation has a wavelength of 280 -100mm, this very short wavelength radiation are blocked by the earth’s atmosphere even before it reaches you. But not all sunscreens protect against UVA radiation and over exposure to this type of radiation can, over time cause skin cancer.

The organic particles within the sunscreen (often a chemical called octyl methoxycinnamate or oxybenzone) absorb the rays; these are then dissipated within the body as heat which therefore prevents your skin burning. The inorganic particles (often zinc oxide or titanium dioxide) reflect and scatter the radiation which forms a physical barrier and therefore also helps prevent the skin from burning. It is these inorganic particles in the sunscreen which makes it appear white; however nowadays the particles are so small the sunscreen is clear so you can’t see it.

Clearly labelled on every sunscreen bottle is the “SPF” which stands for the sun protection factor. This only measures the amount of UVB radiation protection which that particular sunscreen provides. This SPF works on the basis that you would burn if you were in direct sunlight for one hour and therefore with an SPF 15 you could stay in the sun for fifteen hours. However this should only be treated as a basis given that there is a higher level of UV radiation at midday since the sun is lower in the sky. So the amount of time that you can spend safely out in the sun depends on the time of day as well as the level of sunscreen that you have applied and how well the sunscreen has been absorbed.

Is the sun actually good for you?

Thunderstorms earlier today across the south east of the UK marked the climax of the heat wave that brought the hottest temperatures in seven years. The temperature even reached 33^oC in Heathrow, London yesterday. But is the sun actually good for you?

Sure the sun has some health benefits as is widely known, for example it can decrease your chances of getting diseases like Rickets, which is a painful bone softening condition caused by a vitamin D deficiency. As little as

half an hour of sunshine can provide you with more vitamin D than in six tablespoons of cod liver oil or 200 eggs.  Recently the British Medical Journal reported a rise in the number of cases of rickets, which has been blamed due to children staying indoors playing on video games, however much like any disease or illness there are a lot more causes of rickets. For example if you have darker skin you are more susceptible to rickets, so a growing number of cultural backgrounds in the UK could possibly also be partly to blame.

Are you one of the 250,000,000 nut allergy sufferers in the UK? If so then you may well be surprised to find out that if you were to live in Australia, or anywhere in the less sunny south then you would be more prone to develop or to have an allergy to eggs or peanuts than children who live in the north almost 4,800km closer to the equator and which would therefore have a hotter climate. Those are also twice as likely to develop eczema. Researchers at the Peninsula College of Medicine and Dentistry now want to go on to look at if this is down to a Vitamin D deficiency or other factors such as temperature.

Some would quite understandably stay indoors in the tropical conditions and may not like the sun surprisingly you have good reasons to do so, for example some believe that the sun can bring on a tanning addiction. For example some regular beachgoers of the Glaveston Island beach in Texas were showing signs of substance abuse and no not alcohol or narcotics such as heroin or cocaine! The substance was actually UV radiation. The sensation of the UV radiation on the skin creates a feeling of wellbeing, this feeling can actually lead to a physical dependence and lead to obsessive tanning, both indoors and outdoors.

Amongst other effects such as skin cancer or going blind, the “Tortoise face” is one that all of us are presumably keen to avoid, a combination of UVA and UVB radiation (different types of UV radiation) can cause the skin to thicken and loose its natural elasticity. This could well lead to premature aging, wrinkles and bags under your eyes!