UVA rays penetrate clothing. Why are uva rays needed for chickens? Benefits

UVA rays, which reach the surface of the earth all year round and even through clouds, make up 95% of all ultraviolet radiation. They penetrate clouds, glass and the epidermis. Unlike UVB rays, they act painlessly, however, they penetrate very deeply into the skin and reach the dermal cells. The rays provoke the synthesis of free radicals, and their effects are felt subsequently:

• photoaging: a change in the direction of elastin and collagen fibers, as a result of which the skin loses elasticity and wrinkles appear;
• hypersensitivity to the sun, more often called allergies (redness, itching, summer solar dermatitis);
• pigmentation disorders (mask of pregnancy, age spots);
• skin cancer.

UVB RAYS: B AS IN THE WORDS "BURNS" OR "BRONZED SKIN"

UVB rays make up 5% of all ultraviolet radiation that reaches the earth's surface. They contain a large amount of energy, and some of them are retained by clouds and glass. These rays can penetrate the epidermis. Thanks to them, people not only tan, but also get burned, allergies appear, and skin cancer can develop. This is why it is important to protect your skin from both UVA and UVB rays.

Not long ago, some people thought that sunburn was a necessary evil on the path to a “good tan.” And they said when the inevitable burning and peeling appeared: beauty has a price.

Sun sufferers did not know then that they were setting the skin up for damage to its structural proteins and DNA. Hello wrinkles, liver spots and cancer. Regardless of your skin type, ultraviolet radiation (UV) from the sun or tanning beds can damage your skin.

Today, recognition of the risks associated with UV rays has prompted scientists to study what happens in our cells when they are exposed to the sun and develop modern methods reflection of this damage.

What happens when the sun affects your skin

Sunlight is made up of particles of energy called photons. The visible colors that we see with our eyes are relatively harmless to our skin. These are ultraviolet (UV) photons from the sun that can cause skin damage. Ultraviolet light can be divided into two categories: UVA (in the wavelength range 320-400 nm) and UVB (in the wavelength range 280-320 nm).

Our skin contains molecules that are perfectly structured to absorb the energy of UVA and UVB photons. This turns the molecule into an energetically excited state. And as they say, what goes up must come down. To release the acquired energy, these molecules undergo chemical reactions and biological consequences occur in the skin.

Interestingly, some of these effects were considered beneficial adaptations - although we now recognize them as forms of damage. Tanning occurs due to the production of additional melanin pigment caused by UVA rays. Sun exposure also turns on the skin's natural antioxidant network, which deactivates highly destructive reactive oxygen species (ROS) and free radicals; If left unchecked, this can lead to cell damage and oxidative stress in the skin.

We also know that UVA light penetrates deeper into the skin than UVB, destroying a structural protein called collagen. As collagen breaks down, our skin loses its elasticity and smoothness, leading to wrinkles. UVA is responsible for many of the visible signs of aging, while UVB light is considered the main source of sunburn.

The DNA itself can absorb both UVA and UVB rays, causing mutations that, if not corrected, could lead to non-melanoma (basal cell carcinoma, squamous cell carcinoma) or melanoma skin cancer. Other skin molecules transmit absorbed UV energy to RVCs and free radicals. The resulting oxidative stress can overload the skin's built-in antioxidant network and cause cellular damage. MERs can interact with DNA, forming mutations, and with collagen, leading to wrinkles. They can also interrupt cellular signaling pathways and gene expression.

The end result of all these photoreactions is photodamage, which accumulates over a lifetime from repeated exposure. And this applies to all skin types, from Type I (eg Nicole Kidman) to Type VI (eg Jennifer Hudson). No matter how much melanin we have in our skin, we can develop UV-induced skin cancers, and we will all eventually see signs of photon-induced aging in the mirror.

Filtering photons before damage

The good news, of course, is that the risk of skin cancer and visible signs of aging can be minimized by preventing overexposure to ultraviolet radiation. When you can't avoid the sun altogether, today's sunscreens there is your back (and the rest of your skin too).

Sunscreens use UV filters: molecules specially designed to reduce ultraviolet rays reaching the surface of the skin. The film of these molecules forms a protective barrier that absorbs (chemical filters) or reflects (physical blocker) UV photons before they can be absorbed by our DNA and other reactive molecules deeper in the skin.

In the United States, the Food and Drug Administration regulates it as a drug. 14 molecules approved for use that block sun rays. There are only two molecules that block UVA - avobenzone, a chemical filter; and zinc oxide, a physical blocker, which is a testament to our more recent understanding of how UVA causes problems, not just tanning.

On labels since 1971, SPF represents the relative time it takes for a person to become sunburned by UVB radiation. For example, when it usually takes 10 minutes to tan, when used correctly, an SPF 30 sunscreen should provide 30 times more protection than 300 minutes of protection before tanning.

“Used correctly” is the key phrase. Research shows that the average adult's body requires about 30 ml of sunscreen to cover exposed areas. Most people use between a quarter and half of the recommended amounts, putting their skin at risk.

In addition, the effectiveness of sunscreen is reduced in water or by sweating. To help consumers, now sunscreens, labeled as "water resistant" or "very water resistant" should last up to 40 minutes or 80 minutes, respectively, in the water, and recommend reapplication immediately after any water sports. General rule consists of reapplying approximately every two hours and, of course, after water sports or sweating.

To achieve high SPF values, several UVB UVB filters are combined into a formulation based on safety standards. However, SPF does not take UVA protection into account. For a sunscreen to claim to have UVA and UVB protection and to be labeled "Broad Spectrum", it must undergo a large-scale test where the sunscreen is hit with a large dose of UVB and UVA before its effectiveness is tested.

This pre-irradiation step was established in sunscreen labeling regulations and recognized something important about UV filters: some can be photolabile, meaning they can degrade when exposed to ultraviolet radiation. The most famous example may be para-aminobenzoic acid. This UVB absorbing molecule is rarely used in sunscreens today because it forms photoproducts that cause an allergic reaction in some people.

But the broad spectrum test only really came into play once, when the UVA-absorbing molecule avobenzone hit the market. Avobenzone may interact with occinoxite, a strong and widely used UVB absorber, in a manner that makes avobenzone less effective against UVA photons. On the other hand, the UVB filter's octocrylene helps stabilize avobenzone so it lasts longer in its UVA-absorbing form. Additionally, you may notice the molecule ethylhexylmethoxyrilene on some sunscreen labels. It helps stabilize avobenzone even in the presence of occinoxate and provides longer-lasting UV protection.

The next thing in sunscreen innovation is expanding its mission. Since even the highest sun protection SPF products do not block 100% of UV rays, adding antioxidants can provide a second line of defense when the skin's natural antioxidant defenses become overwhelmed. Some antioxidant ingredients include tocopherol acetate (vitamin E), sodium ascorbyl phosphate (vitamin C). And sunscreen silicon researchers are beginning to explore whether the absorption of other colors of light, such as infrared, by skin molecules should play a role in photodamage.

As research continues, one thing we know for sure is that protecting our DNA from UV damage, for people of all colors, is synonymous with preventing skin cancer. All health agencies emphasize that research shows that regular use of SPF 15 or higher prevents sunburn and reduces the risk of nonmelanoma cancer by 40 percent and 50 percent.

We can still enjoy our time in the sun. We just need to use the resources available to us, from long sleeves to shade to sunscreens to protect our skin molecules, especially our DNA, from UV damage.

Since the sun in Russia is increasingly beginning to come into its own, and the spring-summer holiday season is about to begin, it’s time to touch on the topic of sunscreen and SPF. Moreover, some of my readers themselves ask for this. In general, I thought that I knew quite a lot about SPF, and writing a short post would not be difficult. Not so! There are so many nuances and contradictions around this topic, so many opinions and speculations that my brain boiled... I decided to approach the issue of the need for products with SPF from the perspective of skin aging, i.e. actually expanding on one aspect of my recent article - Are there effective anti-wrinkle creams and serums??

We all age in one way or another, this is a natural physiological process that cannot be resisted. this moment time is impossible (alas and ah!). But many people confuse premature aging (which can be corrected) with signs of natural chronoaging, although often these processes occur in parallel.

This is how humans are designed, that the first signs of aging are revealed by our skin. Premature aging is not a fiction, but a scientifically proven and comprehensively studied process. The most common cause of premature skin aging, scientists say, is excessive exposure to ultraviolet radiation, otherwise known as photoaging . People who spend a lot of time in the open sun or in tanning beds have drier, looser skin, covered with a fine network of wrinkles and hyperpigmentation. They look older than they are biological age, and this is no coincidence.

Free radical theory

Oxygen seems to be vital for us humans, but at the same time it can play a cruel joke, causing “oxidation” of cells (oxidative stress). Let's imagine a normal stable oxygen molecule (in the picture on the left). She happily lives and thrives, together with her paired electrons, revolving around her atom. And suddenly, something terrible happens (for example, intense solar irradiation) - one of the paired electrons “flies out”. That's it, the system collapses - a normal oxygen molecule turned into a free radical and entered the warpath (in the picture on the right).

What does it mean? It’s simply that she won’t calm down until she gets the lost electron back. Where will she find him? Of course, from a neighboring molecule, and the first one to fall under the hot hand. Having stolen an electron from its neighbor, the oxygen molecule stabilizes again. But now the neighbor is outraged! She also doesn’t want to walk around without a paired electron, so she also steps onto the slippery slope of theft. And off we go.

In general, free radicals are constantly formed in our body, as a result of many chemical processes occurring. Fortunately, the body is equipped with an antioxidant defense mechanism, i.e. controls the process of cell damage due to oxidation. An antioxidant is a generous and magnanimous molecule; it has an “extra” electron and is ready to give it to the “damaged molecule” free of charge, if only it calms down and does not steal from its neighbors.

The only problem is that this natural antioxidant protection weakens with age. There are more and more free radicals, but there are not enough antioxidant donors for everyone. And we add fuel to the fire - with our rash actions we lead this system to even earlier wear, constantly testing its strength.

Free radicals strike the first blow, of course, on the skin, causing the appearance of wrinkles, signs of inflammation, etc. In the skin, collagen, a protein that gives the skin firmness and elasticity, is most affected by free radicals. Collagen molecules become fused into bundles, lose their elasticity and become stiff, which manifests itself as signs of skin aging. Reasons that trigger the mechanism harmful effects free radicals in the skin are different, but the most insidious is the effect of ultraviolet radiation on the skin. Sun rays stimulate the formation of free radicals and the production of enzyme proteins that destroy fats. So, beauties, the first logical conclusion is that it is easier to prevent damage than to treat its consequences.

Difference between UVA and UVB radiation

To learn how to wisely choose skin protection products from ultraviolet radiation (Ultra Violet - UV), you must first understand what it is. Despite the fact that only 5% of all solar radiation reaches the Earth's surface, it is very powerful and far from harmless.

Next come the mid-range rays - ultraviolet B (or UVB). They reach the ground and also reach the epidermis and are responsible for the production of melanin in the skin. As a result, the skin becomes tanned, which is only an attempt by the skin to protect itself. It is an “overdose” of UVB radiation that leads to skin burns.

But the long-wavelength range of ultraviolet A (or UVA) makes these rays “all-terrain”. They make up 95% of all ultraviolet radiation reaching the Earth. They penetrate clouds, glass and of course the epidermis. Moreover, they reach the dermis, where they contribute to the formation of free radicals, which trigger the chain reactions mentioned above. Their cunning lies in the fact that they do their dirty work painlessly. The consequences are visible later - in pigmentation disorders, loss of elasticity, dryness, the appearance of wrinkles, sun allergies and even skin cancer (melanoma).

What is SPF?

Now you can move on to the concept of SPF - sun protective factor or sun protection factor. In fact, it is a numerical index from 4 to 100 that helps determine how long you can stay in the sun without fear of getting burned. There is such a concept - the minimum erythemal dose (MED). This is the period of time required for the skin to develop redness (erythema). The average dose is 15 minutes of exposure to open sun.

So, the SPF numbers just show us how many times we can increase our erythema zone, i.e. the time during which we can stay in the bright sun without fear of burns using this product. For example, by applying a product with index 15, we can stay in the sun fifteen times longer, i.e. approximately 225 minutes.

What kind of SPF filters are there?

The SPF index depends on the mixture and concentration of special ingredients - UV filters. They are physical (reflective) and chemical (light-absorbing).

Chemical UV filters(aka organic) are specially synthesized substances that absorb ultraviolet radiation, react with it, as a result of which it is neutralized. Thus, these filters literally take the hit and block the penetration of sunlight to the skin. On sunscreen labeling, chemical filters can be found under names such as cinnamates, salicylates, benzophenones, etc. Light-absorbing filters are very effective and provide high SPF values ​​- 25-40 units and above. Unlike mineral filters, organic filters are resistant to water and do not leave whitish stains on the body.

All the salt is in the ingredients

When choosing a sunscreen, reading the label and ingredient list is especially important. Do you hear? ESPECIALLY IMPORTANT. The thing is that a high price and a high SPF index do not yet guarantee complete sun protection. There are ingredients that only protect against UVA or UVB radiation. And it’s important for us to get both, isn’t it? That is, we need wide range of protection, which is often labeled broad spectrum on packaging.

However, it does not guarantee that you will receive complete protection from UVA or UVB rays (partial - quite). Therefore, to make the task easier, here is a list of UV filters commonly found on labels:

UVA protective ingredients:

Zinc Oxide -
Avobenzone or Butyl Methoxydibenzoylmethane -

Mexoryl SX, also known as Ecamsule or Terephthalylidene Dicamphor Sulfonic Acid -

Tinosorb S or Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine -

Tinosorb M or Methylene Bis-Benzotriazolyl Tetramethylbutylphenol -
Butyl Methoxydibenzoylmethane -

UVB protective ingredients:

Trolamine Salicylate -
Octyl salicylate or 2-ethylhexyl salicylate -
Ethylhexyl triazone or Octyltriazone -

Partial UVA and UVB protective ingredients:

Sulisobenzone -

Menthyl anthranilate, also known as Meradimate -

Titanium Dioxide -

Octyl Methoxycinnamate -
Isoamyl p-methoxycinnamate (or Amiloxate) -

Phenylbenzimidazole -

Benzophenone-4 or 8 -

Menthyl Anthranilate -
Ethylhexyl methoxycinnamate -

Many people think that SPF100 will give them 2 times more protection than SPF50. In fact, SPF50 is able to block up to 98% of radiation, and SPF100 - 99%. If you use products with SPF 30-50 correctly, then even people with sensitive skin able to avoid sunburn.

3. Not Oxybenzone. This ingredient easily penetrates the skin, enters the bloodstream and behaves like the hormone estrogen. It is also capable of causing allergic dermatitis. This fact once again confirms the need to carefully study the list of ingredients before purchasing sunscreen.

4. Do not use SPF in powder form. Most often they contain titanium dioxide and zinc, which can enter the body through the respiratory tract. Some studies indicate that titanium dioxide may be a potential carcinogen. This also applies to loose makeup powders.

5. Do not buy sun protection containing vitamin A. Aka retinol, retinyl palmitate and so on. When exposed to sunlight, retinoids can accelerate the formation of tumors.

A few final safety rules

1. Do not use Sunscreen as a tool to extend your time under the scorching sun.

2. Take cover! hats, Sunglasses and T-shirts - best protection. Just look at Nicole Kidman and her healthy sun exposure habits. It always covers the upper body. It may not be as sexy as a backless bikini, but it dramatically reduces the risk of skin cancer. And her husband loves her! And she looks great!

3. Don't let your skin get sunburned!

4. Choose a sunscreen with ingredients that block UVA rays, not just UVB.

5. Get tested for vitamin D levels in your body. If you are deficient, it's time to start taking it as a supplement. Vitamin D may reduce the risk of developing melanoma, the most dangerous type of skin cancer.

6. If possible, try to purchase sanitary blocks marked waterproof (waterproof) and sweat-proof (sweat-resistant). Such sanitary blocks provide more reliable protection. But don't be lulled into a false sense of security. Such protective products should also be reapplied after 1-2 hours, after swimming and drying with a towel, just like regular sanitary blocks.

Where to look for a reliable and safe cream with SPF?

You can choose from specialized beach products and active sports, look for daytime moisturizers, lip balms and decorative cosmetics. You can further narrow your search by selecting other filters:

• non-mineral (i.e. chemical SPF)
• mineral (i.e. physical SPF)
• SPF less than 50
• lower cost (budget options)
• no oxybenzone (without oxybenzone)
• no vit.A (without vitamin A)

Convenient, but there are three problems. The first one is the most obvious, English language Not everyone knows. Second, EWG ranks products that are only available for sale in the United States. Most of these funds are not presented on Russian market, so you can only get them through trips abroad or ordering online. Third, the EWG itself admits that more effective SPFs have already been approved in Europe, and in the USA the well-known Food and Drug Association allows the use of fewer sunscreen filters. Moreover, EWG emphasizes that sunscreens are much more regulated in Europe than in the United States, leading to higher quality and safer products for consumers.

Beauties, I urge you to check your SPF-labeled products for active ingredients that block both UVB and UVA rays. It will be great if you share your discoveries. Was this post helpful to you? Are there any other questions left unanswered on this topic?

My search for the perfect moisturizer for the summer with a high and broad degree of protection is still ongoing!

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Many, having watched enough television programs, are deeply imbued with the topic - and now they are looking at jars and tubes with passion, driving sunscreen cosmetics sellers crazy with questions about the PPD level.

If they don’t find such an abbreviation, they panic, believing that the cream does not protect against dangerous sun rays. Is it really?

No. Let's figure out what PPD is and why this abbreviation is not always present on the packaging.

As you know, there are two types of sun rays that negatively affect the skin:

Spectrum B rays (UVB) are medium ultraviolet waves, the effects of which are manifested by tanning or burns,

Spectrum A (UVA) rays are long ultraviolet waves that penetrate deep into the skin, damage the dermis and accelerate skin aging. Also, UVA rays cause an allergic skin reaction to the sun and cause pigmentation disorders (neither glass nor clothing protects from spectrum A rays).

Spectrum B rays protection is the well-known acronym SPF. (Sun Protection Factor). Now all sunscreens have it, so we will not consider the issue of this type of protection.

But the abbreviation PPD (Persistent Pigment Darkening) is an indicator of protection against spectrum A rays. Why are we looking and not finding the coveted letters PPD on the tube?

There may be several options.

OPTION 1. Most often such information is available. It’s just “encrypted” in the form of a “UVA in a circle” icon. This symbol indicates that the sunscreen has a safe and dermatologist-recommended PPD level. . According to the recommendations of the European Commission, sunscreens must have a PPD of at least 1/3 of the declared SPF and a critical wavelength of more than 370 nm. The product can then be classified as a broad spectrum sunscreen, which covers the UVB rays of interest.

Essentially, PPD is an "internal use" index used by manufacturers to determine whether a sunscreen product meets standards. The consumer does not need to delve into these subtleties - it is enough to see the “quality mark”: the letters UVA in a circle.

Well-known pharmaceutical brands have PPD much higher than the European standard. For example, in Vichy sunscreen cosmetics the PPD is approximately 25 units, and in some La Roche-Posay products it reaches 42.

OPTION 2. Instead of PPD, another marking is used - PA with "pluses". Often such markings can be found on Asian cosmetics.

Here is the PA - PPD index correspondence plate:

PA+ = PPD 2 to 4

PA++ = PPD 4 to 8

PA+++ = PPD from 8 to 16

PA++++ = PPD 16 and above

OPTION 3. Protection against spectrum A rays is indicated by the inscription “broad spectrum”, indicating simultaneous protection against UVA and UVB rays. Only products that have passed FDA tests for UVA and UVB protection can be labeled "broad spectrum" and only those with an SPF of 15 or higher can be considered effective in reducing risk of developing skin cancer and premature skin aging when used correctly (and labeled accordingly).

Let's take for example one of the best sunscreens on iHerb Badger Company, Zinc Oxide Sunscreen Cream, SPF 30, Unscented, 2.9 fl oz (87 ml)

Read the description:
- zinc oxide
- For active people
- SPF 30
- Safe
- Effective
- Suitable for the whole family
- Water resistant for 40 minutes
- UVA-UVB
- Biodegradable
- Certified by the Natural Products Association
- 100% naturally certified
- 98% organic ingredients
- Certified B Corporation
-PA+++
- 381 nm spectrum

As you can see, PPD is not mentioned in the description. BUT! This is a zinc oxide based cream which is the best physical UVA shield. It by definition protects against both UVB and UVA rays (note: titanium dioxide, another physical filter, is less protective against UVA). This time.

The description indicates PA+++, which corresponds to PPD from 8 to 16. This is exactly 1/3 of SPF30 - the ratio recommended by the European Commission. That's two.

There is a postscript UVA-UVB and the inscription on the tube “Broad spectrum” while at the same time SPF is above 15, which means broad spectrum protection, and not just from spectrum B rays. That's three.

And there is an inscription about the critical wavelength - 381 nm. Considering that this is more than the recommended European norm - 370 nm, we have fourth proof of UVA protection.

Thus, in cosmetics, we are not interested in a specific index*, which can be called anything - PPD, PA+++, etc. - but in the fundamental presence of protection from A-rays.

As can be seen from the examples, most often it is there. Therefore, don’t panic - carefully study the description - and calmly go on vacation!

The only thing to remember is that no sunscreen can completely protect against UVB and UVA. Do not neglect the generally known rules of safe exposure to the sun!

*for reference: the IPD index, which is often written about on the Internet, is no longer used in either the US or Europe.

Tanning equipment has become one of the fastest growing industries in the world. This is mainly due to the various benefits it can provide to the user from a medical and aesthetic point of view. The main purpose of tanning beds is to produce an artificial tan for their users. Over the years, tanning technology has been developed to meet the growing need for vitamin D, with sunlight being considered as its main source.

Tanning beds emerged as a useful device for consumers who wanted to tan in the most effective way.

What are the differences between UVA and UVB rays? It is important to first become familiar with the comparison between these two types of UV rays used for tanning. UVA rays are longer wavelengths of ultraviolet rays that penetrate deep into the inner layers of the skin, while UVB rays can penetrate the outermost part of the skin. These types of UV rays can provide comparative results to the consumer. UVB Tanning beds create shorter wavelengths of ultraviolet rays to increase the production of melanin, the brown pigment from our skin. UVA tanning beds on the other hand are used to maintain melanin production to achieve desired tanning results. It can also penetrate into the deeper layers of the skin such as spinush.

Although both types of tanning beds can produce controlled UV light, it performs its functions separately. UBA Tanning salons can be used for longer tanning sessions, while UVB. Tanning beds are limited to short sessions due to the higher risk of burning. UVA humidifiers are equipped with adjustable solar lamps and a frequency ballast to control the machine's UV emissions. Modern bed designs can emit an average of 93% to 99% UVA radiation, or three times the UVA radiation from the sun. UVB beds, on the other hand, have a variety of low and high pressure solar lamps that produce faster radiation depending on a person's tanning desires. Another difference between the two is the appearance on the skin. UVA moisturizing beds give a more tanned complexion, while UVB is responsible for bringing melanin to the surface of the skin. In addition to frequent use of these beds, UVA beds can give you skin problems such as immature skin aging, rashes and wrinkles, while UVB can lead to more serious problems with health problems such as skin cancer.

The leather industry continues to develop a combination of UVA and UVB to meet both tanning requirements. It is always recommended to tan in a moderate way, should the goals improve appearance skin, obtain sufficient nutrients for vitamin D or gain comfort from internal tanning. Most sunrooms built today provide competitive results based on comfortable bed design, lower electrical usage and environmentally friendly lamps. Manufacturers believed that moderate use of the beds produced safer results. There is still a long debate between the industry and clinical studies that say overexposure to radiation can lead to more serious skin health problems.

Briefly from the discussion, the main differences between UVA and UVB tanning are as follows: 1. Penetrating effects of ultraviolet rays on our skin 2. Skin color results based on doses received by each bed type 3. Skin damage from overexposure 4. Type of ultraviolet rays produced by the tanning machine 5. Time period in each session