The SkinGenesis guide to sun protection, sunscreen, sun cream and sun lotion

Staying safe in the sun and making sure you have adequate sun protection is a little more involved than choosing a tube of sunscreen, sun cream or sun lotion with the same SPF (Sun Protection Factor) that you always use.

The purpose of this guide is to help you understand the effects of solar radiation, and in particular UV (Ultra Violet) radiation, on the skin and body and to give you a practical guide for choosing sunscreen, sun cream and sun lotion, and managing your sun exposure.

While UV radiation only makes up 5% of sunlight, as far as our skin and bodies are concerned it is the most significant type of solar radiation.  So it is UV that we are most concerned about here and the guide starts by explaining what UV radiation is.  Use the content links below to jump to other parts of the guide.

What is UV radiation?

UV radiation is high energy and short wavelength, and is not normally visible to the naked eye.  However, it is absorbed by the eye, especially by the lens and the cornea, and so good quality sunglasses are important (but beyond the scope of this guide).

UV radiation is split into 3 bands, UV-A, UV-B and UV-C. We don't have to deal with UV-C as it is absorbed by the atmosphere and doesn't reach the earth's surface.

Of the two UV bands that reach the earth's surface, UV-B is the shortest wavelength and will normally only penetrate the top layer of the skin. The longer wavelength UV-A is capable of penetrating deeper into the structure of the skin.

What are the good things about sun exposure and UV radiation - or should I always use sunscreen?

UV radiation does a number of good things for us.  The one most people are aware of is that UV-B radiation is needed for the production of vitamin D.

Vitamin D is essential for healthy bones and a lack of the vitamin will cause rickets. This is because Vitamin D assists the absorption of calcium in your diet, and is also essential for a strong immune system.

Research has shown that high levels of vitamin D will also reduce the risk of active TB by 32%, and is associated with lower risks for Hodgkin lymphoma, as well as breast, ovarian, colon, prostrate, pancreatic and other cancers.

Less well known is that UV radiation increases blood levels of natural opiates called endorphins - this is the same sort of 'high' you get after vigorous exercise. The production of endorphins is why most people feel good when in the sun.

The final 'feel good factor' of going in the sun is that sunlight regulates serotonin and melatonin production. Melatonin is a hormone responsible for stimulating the body's daily rhythms and affects mood, energy and sleep quality. It also plays an important role in countering infections, inflammation, cancer and auto immunity. Serotonin is necessary to produce melatonin. Moderately high serotonin levels are associated with positive moods and a calm and focused outlook. Seasonal affective Disorder (SAD) is associated with low serotonin levels.

Why do some people get a sun tan while others burn - even with sun cream?

Of course, we all know that it's possible to get a tan in the sun and it's UV radiation that's responsible for this.  Both types of UV radiation play a part in this as UV-B is responsible for stimulating the production of melanin (a chemical that reacts to light), while UV-A radiation causes the melanin to pigment, i.e. turns the melanin brown in the case of eumelanin, or pink/red in the case of pheomelanin.

Those that tan brown will find that the tan offers some protection against further melanin absorption from UV exposure, while those (who produce more pheomelanin) with fair skin that turns pink will not get the benefit of a protecting tan and are much more likely to burn.

Now let's consider the dangers of going into the sun.

What are the risks of not using sunscreen?

The three main forms of skin cancer - melanoma, basal cell carcinoma and squamous cell carcinoma - are largely attributed to excessive sun exposure and inadequate use of sunscreen

Skin cancer is the most common form of cancer among such groups as the white residents of Australia and New Zealand. The Australians have led the world with their public health campaigns for adequate sun protection and use of sunscreen.

Malignant melanoma accounts for about 75% of deaths associated with skin cancer.  According to the WHO (World Health Organisation) about 48,000 deaths from melanoma will occur each year, of which 75% will be white Caucasian males living in sunny climates.

UV-B radiation is primarily responsible for both basal and squamous cell carcinoma, which as their names imply are cancers that affect the epidermis. UV-B is also the radiation most associated with sunburn.

UV-A radiation is now strongly associated with melanomas and is strongly suspected of increasing the cancer causing effects of UV-B. UV exposure causes free radicals which damage the cell structure of the skin and this consequently will visibly age the skin. Thread veins, uneven pigmentation, coarse leathery texture, actinic keratosis and solar lentigos are common signs of sun damage.

The UV radiation that accompanies strong sunlight can damage the eyes (cataracts, age related macular degeneration) and care should be taken to protect the eyes as much as the skin.

UV radiation destroys folic acid which is essential for DNA reproduction and repair.

Should I avoid sun exposure?

Overall the benefits of moderate sun exposure far outweigh the risks. However the emphasis is on moderate.

To maximise vitamin D production in England about 2 hours per week full body exposure to spring sunshine would be enough. That would enable a typical white skinned person to partly (face and arms) expose themselves for up to half an hour a day and get all the benefits with minimal increased risk of skin cancer .

For serotonin and melatonin regulation only 15 minutes exposure of the retina without sunglasses is required. For best effect this should be as early in the day as possible.

Consequently the best advice is to expose the skin and the eyes to the sun as early in the day as possible for between 15 to 30minutes, certainly no longer than it takes for your skin to start going slightly pink - the first sign of burning.

Managing the Risks - UV Index

The actual amount of safe sun exposure depends on the strength of the UV radiation, and this will vary enormously according to the location, time of year and the amount of cloud cover.

However, UV-A radiation is less affected by these factors and should be regarded as being dangerous between sun up and sun down at any location regardless of the weather or time of year. Its longer wavelengths enable it to penetrate glass and even on overcast days 80% of UV-A radiation will penetrate through the clouds.

The shorter wavelength UV-B radiation is more affected by the variable factors. UV-B radiation is at its strongest between 10.00am and 4.00pm on clear days. Its strength increases with altitude and when it is reflected off shiny surfaces such as sea, sun and snow. In England it is at most potent in summer. Although UV-B accounts for less than 5% of UV radiation it has a lot more energy than UV-A and the dangers from prolonged exposure are very real.

To help you take the necessary precautions a UV Index (also known as UVI) is published by national weather stations. The index indicates risk of damage to the skin from sun exposure at specific locations and takes into account cloud cover and other factors.

The UVI is a result of predicting UV-A and UV-B radiation and making adjustments for meteorological conditions including the ozone layer. The index is graded as follows:

The index is used in conjunction with skin type (Fitzpatrick Scale) to estimate how long a person can stay in the sun before there is a significant risk of sunburn.

The UV Index (UVI) is a linear scale. So a skin type III that would burn after 200 minutes when the UVI is 1, would burn after 100 minutes when the UVI is 2 and would burn after 20 minutes when the UVI is 10.

The amount of radiation indicated by the UV Index assumes that the location is at sea level and there is a clear sky and no reflection. We've already said that factors such as altitude and reflection can have a big influence so you should adjust burn times to allow for various environmental factors that will affect the UV exposure as follows.

1.      85% increase from snow reflection

2.      100% increase above 3,000m altitude

3.      25% increase from white water reflection

4.      50% increase from still water reflection

5.      20% increase from sand or grass reflection

6.      40% increase from wet sand or wet grass reflection

Note that

• 80% of UV-A passes through clouds
• 50% of UV can be reflected into shaded areas

Now it's time to get your calculators out! When calculating the burn time risk from UV radiation all the above factors should be taken into account.

E.g.

a) A skin type II person sitting on a sandy beach when the UV Index is 2 will have the following burn time:- UVI 2 + 20% = 2.4 = adjusted UVI. 100 minutes / 2.4 = 42 minutes burn time.

b)A skin type I person skiing in the Alps on a clear sunny day when the UV Index is 5 will have the following burn time:- UVI 5  + 85% + 100% = 14.25 adjusted UVI. 67 minutes / 14.25 = 5 minutes burn time.

To see the UV Index over the last 36 hours in Leeds go to UV Index Leeds

For a 5 day UV Forecast for the whole of Europe, including the British Isles, go to UV Index Europe

Sun Protection and Sun Protection Factors (SPF) - How to choose your sunscreen, sun cream, sun lotion or tanning lotion.

SPF are the initials of Sun Protection Factor and is found on most tubes and bottles of sunscreen, sun cream, sun lotion, and tanning lotion.

The 'Factor' is the multiplier that you apply to your burn time to calculate the maximum period of time you can stay in the sun without risk of burning. So a sunscreen with an SPF of 10, when applied to the person in example (a) above, would allow that person to be in the sun (42x10) 420 minutes before burning and the person in example (b) would be able to stay in the sun for (5x10) 50 minutes before there was a risk of burning.

Or if a sunscreen of SPF50 was applied person (a) would be able to stay in the sun for (42x50) 2,100 minutes (that's 35hours or all day) and person (b) would be able to stay in the sun (5x50) 250 minutes before they had a risk of burning.

The exposure time is not increased by reapplying the sunscreen. This is important! If the skin type I person in example (a) above used a SPF10 sunscreen after 50 minutes in the sun they would not be able to reapply the sunscreen and stay another 50 minutes in the sun.

The SPF gives no indication how long the sunscreen will remain active and it should be reapplied in accordance with the manufacturer's instructions. Generally speaking sunscreen should be reapplied if you have been swimming or sweating.

SPF only indicates protection against UV-B, the burning radiation. It does not indicate any protection against UV-A radiation. The concept of SPF only indicating protection against UV-B radiation harks back to the era when only UV-B was considered dangerous - because it burned skin and could be associated with carcinomas. Current thinking is that UV-A is at least as dangerous and because there is increasing evidence to associate it with melanomas probably more dangerous.

In order to be sure of some measure of protection against UV-A either a 'full spectrum' sunscreen (e.g. DermaQuest Skin Therapy Solar Moisturiser SPF30) or a sun block (DermaQuest Skin Therapy ZinClear) should be used. Unfortunately neither terms 'full spectrum' or 'sun block' indicate the level of protection provided against UV-A radiation. A star (i.e. *****) system is gradually being introduced to indicate levels of protection and its use will become standardised and more widespread in the next few years.

Sun Protection Lifestyle Factors

Moderate exposure to the sun is essential for a healthy life, however over exposure can have fatal consequences. Being safe in the sun isn't all about checking the UV Index and applying the appropriate sunscreen. Lifestyle plays an important part too.

The following advice won't do you any harm and could save your life. The more we adapt our lifestyle the more we can enjoy and benefit from the sun. :-

Diet is important. Fresh fruit and vegetables are essential. Go for variety, intense colours and freshness.

Top up folic acid. Good foods for folic acid include broccoli, brussel sprouts, asparagus, peas, chick peas and brown rice.

Antioxidants are essential. Intensely coloured berries and red grapes are a good source. Processed tomatoes (e.g. tomato juice or tomato sauce) will help prevent sun burn.

Caffeine and exercise combined will boost the body's immune system against UV radiation.

Dress sensibly. Cover as much skin as possible between 10am and 4pm. Wear a hat and sunglasses.

Stay in the shade when the sun is at its hottest especially if the UV Index is 8 or above.

Apply anti oxidant serums topically to the skin after exposure to the sun.

Remember, UV-A exposure can be dangerous and is possible any time of the day all year in almost any location.

Don't get a tan from tanning tubes. There are no benefits, just risks!

The UV Index is available on most major news sites on the internet i.e. www.gm.tv or www.metoffice.gov.uk .