How powerful is the sun?
The sun is estimated to put out 386 billion megawatts. The suns energy travels through ultraviolet radiation, and these rays are most intense between 10am and 4pm. UV wavelengths are very small and are measured in billionths of a metre. They contain high levels of energy which penetrate our flesh and change the structure of skin cells.
UVA, UVC and UVB - What are UVA, UVC, and UVB?
Ultraviolet frequencies are often divided into three types of wavelengths. These are UVA, UVB and UVC. UVB waves are more damaging than UVA, and so therefore they are also more damaging. UVA and UVB cause skin cancer, including wrinkles and lowered immunity against infections, skin disorders and cancer.
What is UVB?
- UVB affects the outer layer of the skin, and is the main cause of sunburn. It is more likely to cause sunburn than UVA and UVC.
- Creates new Melanin into the skin
- Causes aging on the skin, but at a slower rate than UVA
- Causes moles and some skin cancers (not melanoma)
- Produces Vitamin D, which then lowers the rates of diseases
- Moderate exposure to UVB can be healthy
- Can be blocked by virtually all sunscreens
- It is most damaging between the hours of 10:00 and 14:00, because this is when the sun is at its brightest.
- It is more damaging in the summer, because on average, during the summer, a person takes in 70% of a persons yearly UVB.
What is UVA?
- It used to be thought that UVA only had a minor effect on the skin, and now later research has shown it has a major effect.
- UVA penetrates deeper into the skin
- UVA is more constant than UVB, as it goes throughout the whole day and the year
- Causes melanin to combine with oxygen which creates the tan on your skin
- Not blocked by sunscreen, but is blocked by clothing
- Seems to cause cancer less than UVB
- Causes Melanoma, which is more dangerous than other skin cancers
What is UVC?
- Is absorbed by the ozone layer
- Doesn’t affect the skin in anyway, because it cannot get to it
- Can be found in artificial sources such as mercury arc lamps
Effects of Ultraviolet radiation - What are the effects of ultraviolet radiation?
Overexposure to UV radiation can have damaging health effects. It can have effects on our eyes, immune systems and can also cause skin cancer. Children are at the biggest risk of over exposure to UV radiation. Many studies have proven that sun exposure during the childhood; can lead to an increased risk of melanoma (skin cancer.)
Benefits of sunlight - What are the benefits of sunlight?
UV radiation has not only negative effects, but also has some positive effects. The positive effects are: the warmth from the sun, photosynthesis, light and vitamin D synthesis in the body. There is also a ‘feel good’ factor which people claim to have after being in the sun. People often say that they feel much happier in the summer than in the winter, because it is bright outside. Research has been done to show that sunlight can stop people from going into depression. A disorder called ‘seasonal affective disorder’ (or SAD) is a condition which is experienced by many people during the winter months. Sunlight stimulates the pineal gland in the brain, which produces chemicals caller ‘tryptaamines’ which improve our mood.
The sun provides us with our main source of vitamin D. This happens, because the UVB radiation converts a substance on our skin called ergosterol. However, even though it is a good thing, we only need to be in the sun for ten minutes a day and that would supply us with all the vitamin D that we need. Vitamin D is important for our bones, muscles and immune systems. It can ironically also stop the development of cancerous tumours.
SP factors in relation to exposure time - What is an SP factor, and how can it be related to exposure time?
The Sun Protection Factor (SPF) is a measure of the effectiveness of sunscreen. The higher the SPF, the more protection it has against UVA and UVB. The SPF can also indicate the amount of time someone can be exposed to the sunlight without getting burnt. For example, someone who would normally burn after twelve minutes without any protection could be exposed to the sun for two hours if they applied a sunscreen with SPF 10. The protection of the sunscreen can depend on:
- The skin type of the user
- The amount applied
- How often the protection is re-applied
- Activities the person does
- The amount of sunscreen the skin has absorbed
Sunscreen should be applied 20 minutes before going outside so that the cream can penetrate into the skin. Here are some facts, showing how higher SP factors, let in less UVB rays:
- Factor 15, only 7% of the harmful UVB rays will get through
- Factor 30, only 4% of the harmful UVB rays will get through
- Factor 60, only 2% of the harmful UVB rays will get through
Conclusion - Conclusively, how dangerous is sunbathing?
In conclusion, I believe that sunbathing is very dangerous, but small amounts of exposure of the sun a day can be healthy for us. However, when we have got all of the vitamin D we need from the sun, and then our body does not use the rest and then just disposes of it. When we have been in the sun for about fifteen minutes, then I think we should be very careful and protect ourselves because this case study has shown that the ultraviolet rays are very damaging and can have harmful effects.
