Filters in sunscreens

Their effectiveness is directly determined by UV filters - active components that neutralize the harmful effects of ultraviolet radiation.

Understanding how UV filters work allows you to make an informed choice of sunscreen. The ideal formula should provide not only a broad spectrum of protection and photostability throughout the day, but also comfort in use, as well as safety for the skin and the environment.

In this article, we will consider in detail the mechanisms of action of sunscreen filters, their classification, advantages and disadvantages.

The role of filters in sun protection

Solar radiation is electromagnetic waves of various lengths, among which the greatest danger to the skin is:

• UVB radiation(280-320 nm) - affects the surface layers of the epidermis, causing sunburn and erythema. This type of radiation plays a key role in the development of melanoma and other forms of skin cancer.

• UVA radiation (320-400 nm) - penetrates the deep layers of the dermis, causing photoaging, destruction of collagen fibers, hyperpigmentation and weakening of the skin's immunity.

Modern studies have proven that up to 80% of the signs of skin aging are caused by constant exposure to UVA radiation, which is active even in the cloudiest weather and whose rays have a negative effect even through glass and in the shade.

Filters in sunscreens perform two main functions:

• Absorption, reflection or scattering of UV radiation;

• Prevention of photochemical reactions in the skin that lead to damage to cellular DNA.

Depending on the mechanism of action, all UV filters are divided into four fundamentally different groups: physical, chemical, hybrid, and new generation filters. Let's consider each of them in detail.

Types of filters

Modern sunscreens contain various types of UV filters, which can be classified by chemical structure, mechanism of action, and protection spectrum. Let's consider the main groups:

1. Physical filters.

They are also called mineral and inorganic. They act as microscopic "mirrors", reflecting and scattering UV rays.

2. Chemical filters.

They are also organic. They absorb UV radiation, converting it into thermal energy.

3. Hybrid filters.

Modern sunscreen formulas often combine physical and chemical filters. Their combination helps to:

• Increase photostability;

• Expand the protection spectrum;

• Improve the texture of the product.

Thus, successful combinations of organic and inorganic filters include:

• Zinc oxide + Tinosorb M → complete UVA/UVB protection;

• Avobenzone + Octiocrylene → increased photostability.

4. New generation of filters.

New generation filters have improved characteristics compared to earlier ones. These include:

• Biofilters – extracts of algae, lichens, and polyphenols. This is a large class of organic compounds found in plants and acting as natural UV filters and antioxidants.

• Smart technologies:

• Microencapsulation is a process in which small droplets or particles with beneficial properties are coated to create lightweight capsules. An ideal method for selective release or sustained protection.

• Photostabilizers are substances that prevent the destruction of active components of sunscreens under the influence of solar radiation. Their main function is to maintain the effectiveness of UV filters during the entire time they are on the skin.

Physical filters

Physical filters are micronized inorganic compounds that create a protective screen on the skin's surface, reflecting and scattering sun rays according to the principle of microscopic mirrors.

Advantages of mineral filters:

• Hypoallergenic - an ideal choice for reactive skin;

• Immediate onset of action after application;

• High Photostability;

• Environmentally safe.

Disadvantages of mineral filters:

• They can leave a whitish tint (especially on dark skin);

• They require more frequent reapplication;

• The dense texture can be uncomfortable for daily use.

Modern technologies minimize the disadvantages of physical filters through the use of surface-modified particles, their combination with chemical filters, and special texture formulas.

Two main mineral filters are used in modern cosmetology:

Chemical Filters

Chemical filters are complex organic compounds that absorb UV radiation, converting it into thermal energy. Unlike mineral filters, they require 20-30 minutes to activate after application.

Advantages of organic filters:

• Light textures, invisible on the skin;

• High SPF values ​​at lower concentrations;

• Convenience for daily use.

Disadvantages of organic filters:

• Some components in the composition can cause irritation;

• Require time to activate.

Classification by spectrum of action:

1. UVB Filters

2. UVA Filters

3. Broad Spectrum Filters