To understand sunburn, you need to know how UV provokes inflammation

People have been trying to protect their skin from the sun for at least for the time of ancient Egyptians, and we have known for over a century that exposure to ultraviolet (UV) light is linked to skin burns and cancer. But there is often a confusion on the best way to avoid sunburn, that you can treat it and how much each burn increases your risk of developing cancer. Understanding what sunburn involves cellular level, however, can help.

“Sunburn is an inflammatory reaction,” said Lesley Rhodes of the University of Manchester in the United Kingdom. It occurs when the UV radiation in sunlight damages proteins, fats and DNA in cells of the upper layer of the skin, known as epidermis, launching a cascade of inflammatory effects which lead to redness, swelling, pain and coat.

UVB radiation causes most of these damage, while UVA rays, which have a longer wavelength and also penetrate the skin, contribute much less. “UVB, as a rule, is 1000 times more effective than UVA to cause sunburn,” said Antony Young at King’s College in London.

In response to UV damage, skin cells release inflammatory molecules that dilate the blood vessels in the dermis, the skin layer under the epidermis. This stimulates blood flow to the skin in a few hours. In turn, this improves the infiltration of blood immune cells in the skin, which further increases inflammation.

In people with lighter skin shades, the increase in blood flow gives the skin burned by the sun its pink or red color. Those who have darker skin tones can see their skin transform into different shades of red, gray, brown and black. High blood supply also means more blood liquid leaks in the skin, causing swelling. The swollen and inflammatory molecules stimulate the nerves, which means that the skin burned by the sun is warm and painful.

In serious cases, blisters can also occur, where skin cell plates in the epidermis become so damaged that they are self -destruct. While these dead plates move away from the layers under them, the space between fills with fluid and bubble structures on the skin.

How does the skin burned by the sun healed?

“A slight sunburn will resolve more quickly than a serious burn, when the effects could last 72 hours or more,” said Rhodes.

Healing begins when immune cells in the skin begin to produce anti-inflammatory molecules, generally in a few days after exposure to UV. “It is self-resolved inflammation,” says Rhodes. “Various molecules and cells evolve over time and go from a pro-inflammatory state to an anti-inflammatory state.” As a result, blood vessels stop expanding and all redness, swelling and pain gradually disappear.

Stem cells at the bottom of the epidermis also increase healing by producing new skin cells faster than usual. These replace the damaged, which get rid of or peel off from the surface of the skin in large leaves to make way for new growth. “You always lose the skin, but UV damage improves this cell renewal,” explains Young.

Unfortunately, there is no good quality proof that the application of after-sun gels or aloe vera can accelerate the healing of the skin burned by the sun, explains Rhodes. These lotions mainly offer pain relief by providing a feeling of cooling. Taking cold showers, the application of cold flannels on the skin and the use of pain relievers such as paracetamol (acetaminophen) or ibuprofen can also help this.

What are the long -term effects?

Once the inflammation has died and the cells damaged on the surface of the skin collapsed, the sunburn is finished. But DNA damage to stem cells deeper into the epidermis can have a much longer inheritance.

“You get DNA damage and DNA damage are repaired by cells, but the repair is not 100%perfect,” explains Young. This results in genetic mutations and when these accumulate over time in genes that regulate cell growth and cell division, they increase the risk of growth of skin cells and causing cancer.

Some studies suggest that the test of five sunburns in a decade more than double your risk of melanoma, a form of skin cancer. However, these studies are based on people recalling the frequency they have been burned by the sun, which is subject to errors. It is difficult to quantify exactly the quantity of a sunburn increases the risk of skin cancer, explains Young.

What are the best ways to prevent sunburn?

Melanin skin pigment offers a certain protection because it surrounds DNA in skin cells, protecting it from UV damage. For this reason, people with darker skin shades have a much lower risk of skin cancer than people with lighter skin types – but that does not mean that darker skin cannot be ignited and developing sunburn and DNA damage.

If you are trying to determine the risk of burning a given day, you should assess the UV index, a measure of the ultraviolet radiation. Rachel Abbott at Wales University Hospital in Cardiff says you should apply sunscreen when the index is 3 or more. Generally, the UV index is unlikely to exceed 3 early in the morning or in the evening, or between October and March in the United Kingdom. But UV rays are stronger from the equator, where a sunscreen may be necessary at any time of the year. Fortunately, it should not be guess – there are many free applications that can tell you your local UV index. “I use one every day,” says Abbott.

Most people do not apply a sunscreen to the thickness to which it is tested – 2 milligrams per square centimeter of skin – so Young says that opting for the default SPF 50 Scaren is probably a good idea.

But one of the best ways to avoid sunburn is to stay outside the sun when it is the highest in the sky. In the United Kingdom, it is between 11 a.m. and 3 p.m., while the United States has a longer window from 10 a.m. to 4 p.m. During this period, the sun takes a shorter path through the atmosphere, which means that less UVB radiation are absorbed by air and more of your skin. If you are outside, wearing a hat and long -sleeved clothes can also reduce your risk.