Sunscreen is essential for preventing skin diseases and premature aging. In conclusion: sunscreen should be used in every season. However, experts started to warn about the importance of protection against UV, but that happened only a few years ago.
There are several types of electromagnetic radiation and one of them is UV radiation. Ultraviolet radiation consists of 3 wavelengths: UVA rays (emitting a wavelength from 320 to 400nm and aren’t absorbed by the ozone), UVB rays (the wavelength from 290 to 320nm, partially absorbed by ozone) and UVC rays (are stopped by ozone) -> well, what’s still left from ozone.
UV radiation has some beneficial effects, such as vitamin D synthesis. It also has a positive effects on the treatment of dermatological problems (acne, psoriasis), bone and joint disorders and childhood diseases. However, there are more negative effects (role in pathogenesis of skin cancer, photo-aging and photo-immunosuppression) than positive.
| UVA | UVB | |
| Acute effects | Immediate pigmentation, photosensibilisation | Erythema, edema, pigment darkening, thicker epidermis, synthesis of vitamin D |
| Chronic effects | Photo-aging, immunotoxicity | Photocarcinogenesis, immunotoxicity |
UVA rays
UVA rays represent the largest part of solar radiation. They stimulate the formation of reactive oxygen species or ROS. We’ve already been writing about it in blogs (Vitamin C and After 25th, we begin to grow old). UVA rays increase the number of inflammatory cells and reduce the activity of Langerhans cells, which are the first line of defense of our immune system.
UVB rays
UVB radiation causes sunburn. It represents about 18% of total solar radiation and it’s 50-100x stronger than UVA radiation. Our DNA molecules absorb UVB light very well, which can lead to mutation and carcinogenesis. They can damage biomolecules (proteins, lipids and DNA molecules).
UV rays don’t rest!
A few days ago, we’ve asked on Instagram story some questions about your habits regarding to sunscreens and their usage.
57% use the sunscreen only on the beach
56% prefer using sunscreen with a very high protection factor (50, 50+)
69% apply sunscreen several times a day
22% avoids nanoparticles in sunscreens
It’s a bit worrying that more than half of you use sunscreen only at the beach. It’s true that in winter the sun is significantly weaker comparing to summer, but this doesn’t necessarily mean there are no UV rays. In winter while it’s snowing it’s even more likely to get sunburned, because UV rays reflects from snow (white colour reflects sun rays). Despite the fact that there are clouds, who says UV rays can’t pass these clouds to get to us? Again, not so much, but they pass through. Have you ever heard of a friend who went hiking ant the weather was cloudy and came home as red as a beet? Because we have! So this means that UV rays exists even on a cloudy day.
Why is re-application necessary?
Probably, the ones who had answered that apply sunscreen only once, are asking themselves what the hell? You have applied the cream, okay. So you don’t sweat or touch your face? Consequently, by touching and sweating you remove the cream. Also, UV filters stop working after a certain amount of time, meaning they no longer have the effect of protection.
Sun protection products
The main purpose of sunscreens is to protect the skin against the harmful effects of UV radiation. But in order to achieve this effect, it takes more than just choosing the right UV filter in the appropriate concentration. One of the important things is also technological formulation and other ingredients which can support the effect of UV filter or can decompose it.
There is currently a flood of sunscreen products on the market. The SPFs are from 1-50 +. There are products with low protection (SPF 6-10), medium protection (SPF 15, 20, 25), high protection (SPF 30, 50) and very high protection (50+). According to European standards, UVA protection must represent at least 1/3 of the declared SPF.
Recently, we have seen the SPF mark on almost all face products, whether it’s decorative or nourishing. It is especially popular that UV filters are added to the powders, BB and CC creams.
What’s the problem of foundation with SPF15?
If you didn’t just come from the Stone Age, you probably know that for a SPF written on packaging, the application must be 2mg / cm². You probably don’t know how much of sunscreen that is. For a face it is supposed to be used 2 full fingers of cream. We are not 100% sure, but somewhere we’ve found that 70kg man has to use almost the whole sunscreen in order to achieve the SPF protection written on the packaging. Is this even possible? Not really.
Because of the incorrect or insufficient amount (usually 0.8 mg/cm²) of the sunscreen, the actual SPF on our skin is only 20 to 50% of SPF declared on the packaging. So, when using foundation with SPF15, we usually apply a pump or two. This means the actual SPF on the skin is probably barely 3, if not less.
SPF 30 vs. SPF 50
I think that most of us, who have been more or less introduced to the protection against UV rays, know this graph.
This graph shows us that with the protection factor 30, we achieve approximately 95% of protection against UVB rays. With a protection factor of 50, approximately 96.5% of protection. Experts are arguing whether this 1.5% makes a big difference. We must be aware of the amount of UV filters that must be incorporated into the product with SPF 50 comparing to SPF 30. This increased quantity may be unfavorable for people with photosensitivity disorders. If you don’t have them, it’s up to you, if you want to use higher or lower SPF. Keep in mind that you are likely to apply less product and the actual protection is lower.
Types of UV filters
Currently, two types of UV filters are in use, physical and chemical, both of them minimize the previously listed effects of exposure to UV radiation.
Physical or inorganic filters disperse and reflect UV rays while chemical or organic filters absorb them. More and more studies assess the role of these compounds in developmental and endocrine abnormalities, which have been demonstrated in animal and human studies.
Organic UV-absorbing filters are divided into: PABA derivates (PABA, ethylhexyldimethyl PABA), cinnamic acid derivates (ethylhexylmethoxycinnamate, octylmethoxycinnamate), salicylic acid derivates (homosalate), octocrylene, triazine derivates (ethylhexyl triazone), benzophenone derivates (oxybenzone BP-3), sulisobenzone) and dibenzoylmethane derivates.
Among the physical UV filters that reflect and disperse UV rays are zinc oxide and titanium dioxide. Sunscreens are mostly a mixture of several organic and physical UV filters, because with the combination we achieve broad spectrum protection.
