Developing technologies and irresponsible use of nature have caused the ozone layer that protects the earth to be ruptured and this opening has been expanding day by day.

There is a great deal of oxygen in the breathing air. Oxygen molecules consist of two atoms. Ozone is three atom oxygen. Oxygen is vital for the breathing of living things in parts of the atmosphere close to the earth's surface. Ozone, on the other hand, is found in the top layers of the atmosphere and is a very toxic and very bad smelling gas. Ozone generally occurs in the air layers on the equator belt and air movements are carried to the poles. 25 kilometers above the earth reaches a density of ozone percent 90 above and forms a layer about 20 kilometers thick. Ozone plays an important role in the realization of biological events on earth.

The UV-B and UV-C rays emitted from the sun first collide with the ozone and oxygen molecules in the ozone layer. UV-B rays can only break down ozone, while UV-C rays can break down both ozone and oxygen molecules. During this collision, UV-B rays are trapped by the ozone layer and are prevented from reaching the earth. UV-C rays, on the other hand, form ozone again when breaking down oxygen molecules. However, harmful rays disappear completely.

In this way, the ozone layer protects the world in the harmful UV rays of the sun. Under normal conditions, ozone concentration in inhaled air has to be between 0.1 and 0.4 ppm (ppm, parts per million). If this rate is exceeded, ozone has a toxic effect on living things. In humans, lung diseases increase and more tears occur. It creates acid rain and damages forests and goods. In addition, the ozone layer has an effect on the climate balance of the surface. Global warming in recent years and unexpected weather events are caused by this thinning in the ozone layer. When ultraviolet rays (ultraviolet rays) are held by the ozone layer, the temperature of the earth decreases and the heat balance is achieved.

Recently, when the intensity of ultraviolet rays emitted from the sun has increased, textile products have emerged as a need to protect people from these harmful rays. In particular, protection of eyes and skin was important. In the textile sector, ultraviolet rays permeability of fabrics and materials is affected by many factors such as the type of yarn and fiber used in weaving, moisture content, surface structure of the fabric, finishing processes applied to the fabric and finishing applications.

The factor that is taken into consideration in the protection of textile products against ultraviolet rays is the intensity of this radiation. In order for textile products to absorb UV rays, this feature is realized by finishing processes applied during the production or finishing of the fibers to be used in weaving. This allows the fabric to retain UV rays.

Standards for UV transmittance are being developed by many organizations. Here are a few of the most commonly used standards:

• BS 7914 Test method for the penetration of solar ultraviolet rays through clothing fabrics
• AATCC 183-2014 Transmission or blocking of erythemally weighted ultraviolet radiation from fabric
• AS / NZS 4399: 2017 Sun protection clothing - evaluation and classification

The porosity of the fabrics is a feature that increases the permeability of UV rays. Therefore, fabrics with low air permeability and densely woven fabrics have lower UV transmittance and provide higher protection.

Moisture of the fabric also increase the permeability of UV rays. If the fabrics are wet, they cause the fibers to swell, and the texture structure becomes tighter than the dry state. Therefore, pores are more closed in damp fabrics.

Ultraviolet or purple light transmittance tests of fabrics in authorized laboratories are carried out on the basis of the legal regulations in force and the standards published by domestic and foreign organizations.