UVA rays penetrate clothing. Why do you need uva rays for chickens?

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 deep into the skin and reach the dermis cells. The rays provoke the synthesis of free radicals, and their effect is felt afterwards:

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

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

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

Not so long ago, some 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 to damage 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, the recognition of the risks associated with UV rays has prompted scientists to study what happens in our cells when they are in the sun and develop modern ways to fend off this damage.

What happens when the sun affects the 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) solar photons that can cause skin damage. UV light can be divided into two categories: UVA (in the 320-400nm wavelength range) and UVB (in the 280-320nm wavelength range).

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 effects occur in the skin.

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

We also know that UVA light penetrates deeper into the skin than UVB, breaking down a structural protein called collagen. As collagen degrades, 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.

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

The end result of all these photoreactions is damage that 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.

Photon filtering before damage

The good news, of course, is that the risk of skin cancer and the visible signs of aging can be minimized by preventing excessive UV exposure. When you can't avoid the sun at all, today's sunscreens eat your back (and the rest of your skin too).

Sunscreens use UV filters: molecules specially designed to reduce the amount of 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 as drugs. 14 molecules approved for use that block the sun's 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 later understanding of how UVA causes problems, not just sunburn.

On labels since 1971, SPF represents the relative time it takes a person to get sunburned by UVB radiation. For example, while it typically takes 10 minutes, when used properly, an SPF 30 sunscreen should provide 30 times more protection than 300 minutes of pre-sun protection.

"Used correctly" is the key phrase. Studies show that it takes about 30ml of sunscreen to cover the exposed areas of the average adult body. Most people use a quarter to half of the recommended amounts, putting their skin at risk.

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

In order to obtain high SPF values, several UVB UVB filters are combined into a composition based on safety standards. However, SPF does not account for UVA protection. For a sunscreen claiming to have UVA and UVB protection and to be labeled "Broad Spectrum", it must pass a large-scale test where the sunscreen is hit with a high dose of UVB and UVA before its effectiveness can be verified.

This pre-irradiation step was established in sunscreen labeling regulations and recognized something important about UV filters: Some can be photolabile, meaning they can deteriorate when exposed to UV light. 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 can interact with occinoxite, a strong and widely used UVB absorber, in a way that makes avobenzone less effective against UVA photons. On the other hand, UVB filter octocrylene helps stabilize avobenzone so it lasts longer in its UVA absorbing form. In addition, 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 their mission. Because even the highest SPF sunscreens don't block 100% of UV rays, the addition of antioxidants can provide a second line of defense when the skin's natural antioxidant defenses are overwhelmed. Some antioxidant ingredients include tocopherol acetate (vitamin E), sodium ascorbyl phosphate (vitamin C). And solar silicon researchers are starting to investigate 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 studies show that regular use of SPF 15 or higher prevents sunburn and reduces the risk of non-melanoma cancer by 40 percent and 50 percent.

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

Since the sun in Russia is starting to come into its own more and more actively, and the spring-summer vacation season is about to begin, it's time to touch on the topic of sunscreens and SPF. Moreover, some of my readers ask about it themselves. In general, I thought that I knew enough about SPF that it would not be difficult to write a short post. It wasn't there! There are so many nuances and contradictions around this topic, so many opinions and speculations that my brain boiled... actually expanding on one aspect of my recent article - Are there effective wrinkle creams and serums??

We all grow old in one way or another, this is a natural physiological process, which we must resist on this moment time is impossible (alas and ah!). But many people confuse premature aging (which can be corrected) with signs of natural aging, although these processes often run in parallel.

This is how a person is arranged, that our skin gives out the first signs of aging. Premature aging is not a fiction, but a scientifically proven and comprehensively studied process. The most common cause of premature skin aging, according to scientists, is excessive exposure to ultraviolet radiation, otherwise known as photoaging . People who spend a lot of time in the open sun or in a solarium have drier and flabby skin, covered with a fine network of wrinkles and hyperpigmentation. They look older than their 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 cell “oxidation” (oxidative stress). Imagine a normal stable oxygen molecule (in the picture - on the left). She happily lives and is well, together with her paired electrons revolving around her atom. And suddenly, something terrible happens (for example, intense solar radiation) - one of the paired electrons "flies out". Everything, the collapse of the system - a normal oxygen molecule turned into a free radical and entered the warpath (in the picture - on the right).

What does it mean? But simply that she will not calm down until she returns the lost electron. Where will she find him? Of course, at the neighboring molecule, and the first one that came under a hot hand. Having stolen an electron from a neighbor, the oxygen molecule stabilizes again. But now the neighbor is outraged! She also does not want to walk around without a paired electron, so she also steps on the slippery slope of theft. And off we go.

In general, free radicals are formed in our body constantly, as a result of many ongoing chemical processes. Fortunately, the body is equipped with an antioxidant defense mechanism, ie. controls the process of cell damage as a result of oxidation. An antioxidant is a generous and generous molecule, it has an "extra" electron and is ready to give it to the "damaged molecule" free of charge, if only it would calm down and not rob the neighbors.

The problem is that this natural antioxidant defense weakens with age. There are more and more free radicals, and there are not enough antioxidant donors for everyone. And we are still adding fuel to the fire - with our rash actions we bring this system to even earlier wear, constantly testing it for strength.

Free radicals strike the first blow, of course, on the skin, provoking the appearance of wrinkles, signs of inflammation, etc. In the skin, collagen, the protein that gives skin firmness and elasticity, suffers the most from free radicals. Collagen molecules are soldered into bundles, lose elasticity and become stiff, which is manifested by signs of skin aging. Reasons triggering the mechanism harmful effects free radicals in the skin are different, but the most insidious is the effect on the skin of ultraviolet radiation. The sun's rays stimulate the formation of free radicals and the production of proteins-enzymes that destroy fats. So, beauties, the first logical conclusion is that it is easier to prevent damage than to treat their consequences.

The difference between UVA and UVB radiation

To learn how to correctly 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 rays of the middle range - B-ultraviolet (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 acquires a tan, which is only an attempt by the skin to protect itself. It is the "overdose" of UVB radiation that leads to skin burns.

But the long-wavelength range of A-ultraviolet (or UVA) makes these rays "all-terrain vehicles." 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 that trigger the chain reactions mentioned above. Their cunning is that they do their dirty work painlessly. The consequences are visible later - in pigmentation disorders, loss of elasticity, dryness, wrinkles, sun allergies and even skin cancer (melanoma).

What is SPF?

Now we can move on to the concept of SPF - sun protective factor or sun protection factor. In fact, this is a numerical index from 4 to 100, which helps determine how long you can stay in the sun without fear of getting burned. There is such a thing - the minimum erythemal dose (MED). This is the period of time required for redness (erythema) to develop on the skin. The average dose is equal to 15 minutes of exposure to the 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 a burn, using this tool. For example, by applying a product with an index of 15, we can stay in the sun fifteen times longer, i.e. approximately 225 minutes.

What 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(they are also 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 labels, chemical filters can be found under names such as cinnamates, salicylates, benzophenones, and others. 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 full protection from the sun. There are ingredients that only protect against UVA or UVB radiation. And it’s important for us to get both, right? That is, we need wide range of protection, which is often labeled broad spectrum on packages.

However, it does not guarantee that you will receive full protection from UVA or UVB rays (partial - completely). Therefore, to facilitate the task, here is a list of UV filters often 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 -

Partially 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 2x 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 can avoid sunburn.

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

4. Don't use powdered SPF. 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 sunscreen with vitamin A in the composition. He is retinol, retinyl palmitate and so on. When exposed to the sun, retinoids can accelerate the formation of tumors.

A few final safety rules

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

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

3. Do not bring the skin to sunburn!

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

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

6. If possible, try to purchase sun blocks labeled waterprooof (waterproof) and sweat-proof (sweat-resistant). Such sunblocks provide more reliable protection. But don't fall into a false sense of security. Such protective products should also be reapplied after 1-2 hours, after bathing and wiping with a towel, like regular sunblocks.

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

You can choose from specialized products for the beach 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 (no oxybenzone)
• no vit.A (without vitamin A)

Convenient, but there are three problems. The first is the most obvious English language not everyone knows. Second, the EWG ranks products that are only available in the US. Most of these funds are not represented on the Russian market, so they can only be obtained through foreign trips or ordering via the Internet. Thirdly, the EWG itself acknowledges that more effective SPFs have already been approved in Europe, and in the US, the notorious Food and Drug Association allows the use of fewer sunscreens. Moreover, the EWG emphasizes that the production of sunscreens is much more strictly regulated in Europe than in the US, which leads to higher quality and safety for the consumer of these products.

Ladies, I urge you to test your SPF-labeled products for active ingredients that block both UVB and UVA rays. It would 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!

Do you want to be one of the first to know about new makeup products? Do you want to know how not to waste money on obviously ineffective means? care? Have you always wanted to know what your cream is made of, but were afraid to even think about it? The Beauty Maze mailing list is the answer to these and many other questions. Don't miss a single letter, subscribe NOW !

Many, after watching TV shows, are deeply imbued with the topic - and now they look at jars and tubes with prejudice, driving sunscreen sellers crazy with questions about the level of PPD.

If they do not find such an abbreviation, they panic, believing that the cream does not protect against dangerous sunlight. 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 sunlight that adversely affect the skin:

Spectrum B rays (UVB) - medium waves of ultraviolet radiation, the effect of which is manifested by a tan or burn,

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

Spectrum B protection is the well-known abbreviation SPF. (Sun Protection Factor). Now it is on all sunscreens, 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 do we search - and do not find the cherished letters PPD on the tube?

There may be several options.

OPTION 1. Most of the time this information is available. It's just "encrypted" in the form of a "UVA in a circle" icon. This icon 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 categorized as a broad spectrum sunscreen, which covers the UVA rays of interest to us.

Essentially, PPD is an "internal use" index used by manufacturers to determine if 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 pharmacy brands have PPDs that are 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 8 to 16

PA++++ = PPD 16 and up

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

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)

Reading the description:
- zinc oxide
- For active people
- SPF 30
- Safe
- Efficient
- Suitable for the whole family
- Water resistant for 40 minutes
- UVA-UVB
- Biodegradable
- Certified by the Natural Foods Association
- 100% naturally certified
- 98% organic ingredients
- Certified by 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 protects by definition from both UVB and UVA rays (note: titanium dioxide - another physical filter - protects against UVA less). This time.

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

There is a postscript UVA-UVB and the inscription on the tube "Broad spectrum" while SPF is above 15, which means protection of a wide spectrum, and not just from spectrum B rays. It'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 against A-rays.

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

The only thing to keep in mind is that no sunscreen can fully protect against UVB and UVA. Do not neglect the well-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 in the world 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 salons is to produce an artificial tanned color for their users. Over the years, tanning technology has been developed to meet the growing demand for vitamin D, and sunlight is regarded as its main source.

Solariums emerged as a useful device for consumers who wanted to tan in the most efficient way.

What are the differences between UVA and UVB rays? It is important to first familiarize yourself with the comparison of these two types of UV rays used for tanning. UVA rays are longer wavelengths of ultraviolet rays that penetrate deep into the innermost layered layers of the skin, while UVB rays can penetrate the outermost part of the skin. These types of ultraviolet rays can give 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 support the production of melanin to achieve the desired tanning results. It can also penetrate deep layers of the skin such as spinush.

Although both types of tanning beds can produce controlled ultraviolet radiation, it performs its functions separately. UBA Solariums can be used for longer tanning sessions, while UVB. Tanning salons 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 ultraviolet 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 more rapid radiation depending on the individual's tanning desires. Another difference between the two is the appearance on the skin. Moisture beds UVA give a more tanned color, 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, breakouts and wrinkles, while UVB can lead to more serious problems with health conditions 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, whether the goals are to improve the appearance of the skin, acquire sufficient vitamin D nutrients, or get comfort from internal tanning. Most tanning beds built today provide competitive results based on comfortable bed design, lower electrical usage, and environmentally friendly lamps. Manufacturers believed that moderate use of beds produced safer results. It's still a long debate between the industry and clinical studies, which argue that overexposure to radiation can lead to more serious skin health problems.

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