Almost every day, people are exposed to solar radiation. We used to relax in warm countries and sunbathe in the sun. In order to protect the population from the negative influence of the star, it was decided to calculate a special indicator. The article discusses what the UV radiation index is, what value it can take and how a person should behave after receiving this information.
A few words about the concept
All over the world, the level of UV radiation on the surface of our planet is usually measured by the UV Index. It is calculated in order to help people understand when it is necessary to use various sunscreens.
Description of UV Index:
- The indicator reflects the degree of ultraviolet radiation, it varies from 0 to 11+. The higher its value, the greater the potential threat to the skin and eyes of a person, and, accordingly, the less time you need to be in direct sunlight.
- The UVI index warns when to use sunscreens. Recently, people with fair skin have increased incidence of malignant epithelium. Doctors do not exclude the negative effects of sunlight on the human body.
- The UVI level, as well as the UVI index value can vary at different times of the day. As a rule, indicate its maximum value on a particular day, which is observed in the four-hour period of sunny noon.
How is it calculated?
In clear weather, the UV index is calculated based on:
- the concentration of the ozone layer, the location of a particular territory;
- the position of the sun;
- albedo (reflectivity) of the earth's surface;
- the number of aerosols and their composition;
- the calculation takes into account waves whose length is 100-400 nm.
What does the UV index mean? This is an indicator of the potential risk to the health of a living organism as a result of exposure to ultraviolet radiation on it. Values are presented as a scale with an interval of 1 to 11+. It describes UV radiation reaching the earth at a specific point. The higher the value, the higher the risk of harm to health, eyes and skin.
Recommendations for standardizing the index and applying it at the global level have been developed by world health organizations.
The methodology for calculating the UVI index for clear skies was created by an international consortium of research institutions under the auspices of EUMETSAT, the European Organization for the Exploitation of Meteorological Satellites.
How does the UVI index help protect my skin and eyes from the sun?
A person makes plans for the whole day, decides what to wear, focusing on the weather and air temperature. In the same way as the temperature scale, this indicator reflects the level of ultraviolet radiation and the threat from exposure to the sun. Understanding how to find out the usefulness of the sun by the UV index, and calculating it, you can make a choice that will help maintain health.
Index value and recommended security measures:
- UV index 1-2. With such a low level of radiation, no protective measures are needed. The risk of exposure to the skin and eyes is low, practically equal to zero, if there is no increased sensitivity to UV radiation.
- UV index 3-5. This is a moderate value. There is also no need for substantial protective measures. You can wear sunglasses, a panama hat and use a protective cream SPF 15.
- UV index 6-7. This value is considered high. For protection, it is recommended to use sunglasses, a panama hat, cream with SPF 30 protection on uncovered skin.
- UV index 8-10. Very high standard. It is necessary to use accessible areas with a shadow for shelter (premises, umbrellas, etc.). In the sun it is better to wear wide-brimmed hats, sun glasses, light clothing covering your legs and arms, sunscreen with SPF 30 protection factor.
- UV index 11 and above is extreme. Better not to be in the sun. If it is not possible to wait out the heat, it is better to wear a hat with a wide brim, sun glasses, light clothing covering hands and feet, and use a cream with SPF 50 factor.
For those who have very sensitive fair skin, it’s useful to know what the UV index is. If all the recommendations are followed, the risk of harming one’s health will be minimal.
Who is at risk
Most exposed to ultraviolet radiation, children and adolescents. Adults try to strengthen the health of their descendants every year by relaxing at sea, but prolonged sunbathing can negatively affect their well-being in the future. If you do not pay attention to the UV index and do not follow the recommendations, then skin cancer can develop at an older age. A significant factor is the type of human skin. People who have fair skin are more prone to sunburn, the risk of developing cancer pathologies in them is higher than in the dark-skinned population. Although it is believed that people with dark skin are less likely to suffer from cancer, but, according to statistics, their pathology manifests itself in later stages.
The risk of developing eye disease, reducing the resistance of the immune system and photoaging is the same for everyone.
How to find out the UV index on your own?
Only a meteorologist can accurately determine the indicator. If an ordinary person knows what the ultraviolet radiation index (UV index) is, then he will be able to independently evaluate its value with a minimum error. The following rules will help:
- The value of the index directly depends on the height of the sun, the distance to the equator and the height above sea level. So, the maximum value is fixed in the hours from 11.00 to 16.00. The closer to the equator, the more intense the radiation. And each additional 100 m above sea level increases the value of the index by 5%.
- If the street is cloudy or cloudy, this does not mean that the UV index is zero. The ozone layer of the planet is designed to provide real protection from harmful radiation. Its thickness is usually less in sunny time.
- The index value will be greater in the open area or covered with snow, and less in the shade. In central Russia, the UV index value will be unsafe only in the summer.
Consequences of UV exposure
The UV index shows how dangerous it is to be in the sun. If you follow the recommended safety measures, then the sun's rays will be useful for people and effective for the production of vitamin D. Children’s doctors recommend taking walks with small children at a low UV index, because the child receives solar heat and gets rid of such ailments as rickets, psoriasis, jaundice or eczema.
Prolonged exposure to the sun or walking in unsafe hours has a negative effect on the skin, eyes and immune system. The most common manifestations of negligence are sunburn (or erythema). Prolonged exposure to UV radiation can cause irreversible changes in the skin cells, the appearance of fibrous tissue and the violation of the integrity of blood vessels. Eyes from exposure to ultraviolet radiation may become inflamed. In serious cases, skin cancer or eye disease develops.
Ways to protect from the sun
If a person knows what the UV index is and how to apply its value in life, then the risk of a negative effect on the body is minimal.
Here are some guidelines to keep you healthy:
- It is best to be in the shade, put on sunglasses, use a hat and apply sunscreen to the skin.
- It is necessary to limit the time spent in the midday sun. The most intense radiation is observed from 10 a.m. to 4 p.m.
- It is important to track the UVI index. This will help to distribute the time spent in the fresh air so as to be less under the sun.
- Wear protective clothing. It is better to purchase a wide-brimmed hat, it will be able to protect the eyes, ears and the back of the neck. Sunglasses, tight and spacious clothes are also needed.
- Use sunscreen. Effective means with protection SPF 30+, it is recommended to apply them every two hours.
- Do not use equipment for artificial tanning. It increases the risk of skin cancer and can harm unprotected eyes.
Adults should always remember the safety of children. They are more susceptible to the harmful effects of the environment, and outdoors it is necessary to protect children from the intense exposure to UVI. Breasts should always be in the shade.
What affects the level of UV?
There are several factors that influence the formation of the UV index.
- The UV level directly depends on the height of the sun above the horizon: the higher it is, the higher the UV value.
- Also, there is a dependence on the time of day. The maximum value of the index is fixed when the sun is at its zenith - at about noon in the summer.
- Geographical location: the closer the equator, the higher the UVR.
- Cloud cover: UV levels will be higher in clear skies. But, even if it is cloudy in the sky, the UV level can be high due to the scattering of UV rays by water molecules and small particles in the atmosphere.
- Altitude: At higher altitudes, the atmosphere is sparse, which contributes to the passage of UV rays.
- Ozone layer concentration: it absorbs part of the sun's rays that would reach the Earth’s surface.
- The ability of the planet's surface to reflect UV rays. For example, a layer of snow can reflect up to 80% of the rays, a dry beach - up to 15%, and sea foam - about 25%.
Stereotypes
Adults do not always explain to children what the UV index is. But people have heard some allegations since childhood and consider them to be true.
The table shows some discrepancies:
We can say that the value of UV radiation is an important indicator for modern man. The use of protective measures is necessary not only on holidays in hot countries, but may also be needed at ski resorts.