In recent years, ultraviolet (UV) index It has gone from being an almost anecdotal detail in weather forecasts to becoming an indicator that should be looked at with the same attention as the temperature. Episodes of very high or extreme UV radiation They occur more frequently, especially on days with clear skies and intense heat, increasing the risk of skin and eye damage in a matter of minutes.
Although many of the recent warnings come from countries in the Southern Cone, the same public health recommendations They are fully applicable to Spain and the rest of Europe when episodes of extreme UV indexThe message from health organizations is clear: when the index value skyrockets, it is not enough to "put on some cream"; it is necessary to combine several protection measures and adapt schedules and outdoor activities.
What is the UV index and how is it interpreted?
El Global Solar Ultraviolet Index (UVI) It is a scale standardized by the World Health Organization (WHO) and the World Meteorological Organization (WMO) that indicates the intensity of ultraviolet radiation that reaches the Earth's surface at a specific place and time. It has no units and is expressed with a number: the higher the number, The greater the potential for damage and the skin takes less time to burn.
The values are grouped into risk categories to facilitate understanding: with (0-2), moderate (3-5), high (6-7), very high (8-10) y end (11 or more). Starting at an index of 3 or higher, the WHO advises taking precautions, while very high and extreme levels require strict protection and limiting time in the sun.
In scenarios of UV index 11 or higherThe radiation is capable of producing erythema (sunburn) in very short periods, especially during the middle of the day. This is particularly concerning in mid-latitude areas during the summer, when the sun is higher in the sky and the atmosphere filters less UV radiation.
The importance of this indicator lies in the fact that the Ultraviolet radiation is invisible and imperceptibleIt's not as noticeable as the heat. A day with a pleasant or even slightly cool temperature can have a very high UV index if the sky is clear and the sun is high, which is why meteorological services are increasingly including this information in their bulletins.
Why is ultraviolet radiation a concern?
The ultraviolet radiation that reaches the surface is mainly composed of rays UVA and UVBIn small doses, it contributes to the synthesis of vitamin Dessential for bone health. However, overexposure causes cumulative biological damage: UVB is the main culprit behind the sunburnwhile UVA radiation penetrates deeper into the skin and accelerates the photo aging.
Experts remind us that UV radiation is a recognized carcinogenExcessive and intermittent exposure, especially during childhood and adolescence, is associated with an increased risk of skin cancerincluding malignant melanoma, the most aggressive type. It also contributes to the development of skin carcinomas and precancerous lesions that can go unnoticed for years.
The damage is not limited to the skin. Prolonged exposure to high levels of UV radiation is linked to eye injuries such as cataracts, pterygium, and other conditions that can impair vision. Even intense exposure over a short period can trigger solar keratitis, a painful inflammation of the cornea similar to a "burn" on the surface of the eye.
Furthermore, ultraviolet radiation can influence the immune systemThis increases the likelihood or worsening of photosensitive skin conditions and reduces the body's ability to repair certain types of cellular damage. All these effects accumulate over time, making daily sun protection just as important as taking extra precautions on days with high sun exposure.
Factors that favor extreme UV indices
The level of radiation that reaches the ground depends on several factors. Among the most important is the height of the sun in the skyThe closer to midday and the further into summer, the higher the UV index. Therefore, the hours between... 10:00 and 16:00 They concentrate the greatest risk, and it is in that interval that health organizations recommend limiting direct exposure as much as possible.
La cloudiness Cloud cover also plays a key role. Clear skies or skies with high, thin clouds allow much of the radiation to pass through, while dense clouds partially attenuate it. However, even on somewhat cloudy days, dangerous UV levels can be recorded, reinforcing the idea that the sun "doesn't have to be stinging" to be harmful.
Another factor to consider is the reflection of radiation on different surfaces. Dry sand, water, snow, or light-colored pavement can reflect a significant fraction of UV rays and increase the dose received by the skin and eyes. In fact, in environments like the beach or high mountains, the actual exposure can be greater than what is perceived by the naked eye.
Finally, the variations in the ozone layer and atmospheric conditions influence the filtering of ultraviolet radiation and the protection of the Earth's atmosphereA thinning of stratospheric ozone or certain meteorological configurations can allow more radiation to reach the surface, increasing UV index values, even without appreciable changes in temperature.
Real health risks during extreme UV episodes
When a Extreme UV Index AlertThe main immediate danger is the drastic increase in the risk of sunburnIn situations with an index of 11 or higher, a person with fair skin can begin to burn in just a few minutes of unprotected exposure at midday, and darker skin tones are not exempt from risk either.
Health services also point to the impact on the eyesIntense radiation increases the likelihood of keratitis, corneal damage, and, in the long term, cataracts and other degenerative eye diseases. The problem is exacerbated when they are not used. sunglasses with suitable UV filter and people resort to low-quality lenses that darken vision but do not actually block ultraviolet rays.
For people with history of skin cancer, dermatological diseases, or photodermatosisThese episodes represent a particularly delicate scenario. Any further exposure can aggravate symptoms, accelerate the appearance of new lesions, or interfere with medical treatments that already increase photosensitivity.
Nor should we forget those who work outdoors: construction workers, farmers, urban service workers, and lifeguards, among others. On days with very high or extreme UV radiation, these groups face a high risk of heat stroke, dehydration, and exhaustion with the added burden of ultraviolet radiation, making it essential to reinforce prevention measures.
How to reduce sun exposure on days with extreme sun index
In response to an alert regarding Very high or extreme UV indexThe first recommendation from the WHO, PAHO, and meteorological services is avoid direct exposure Avoid the sun during peak radiation hours, which is approximately between 10:00 and 16:00. Whenever possible, it is advisable to reschedule outdoor activities for the early morning or late afternoon.
When there is no other option but to go out, it is essential look for the shadow Actively take advantage of wooded areas, awnings, porches, or structures that reduce direct radiation. On the beach or in open spaces, an umbrella or tent provides some relief, but it doesn't completely block UV rays, especially those reflected by water or sand.
The recommendations emphasize the use of tightly woven clothingIdeally, long sleeves and long pants that cover a good portion of the body. Dark-colored garments or those with specific UV protection offer greater blocking capacity. Complement the clothing with a wide brim hatWearing a mask that protects the face, ears, and neck significantly reduces the radiation dose received.
El broad spectrum sunscreen This is another essential step. It's advisable to use products with an SPF of at least 30, ideally 50+, applied generously to all exposed areas, including the neck, ears, and backs of the hands. It's important to reapply every two hours and after swimming or sweating heavily, even if the packaging indicates it's water-resistant.
Finally, the wraparound sunglasses Sunglasses that block 99%-100% of UVA and UVB rays are essential for eye care. They should be worn not only at the beach or in the mountains, but also in urban environments when the UV index is high, as pavement and light-colored facades can reflect a significant amount of radiation.
Special recommendations for children and vulnerable groups
Los babies and toddlers Children are especially sensitive to ultraviolet radiation because their skin is thinner and accumulates sun damage more quickly over their lifetime. Health organizations recommend keeping them in the shade during the hottest hours of the day and limiting their time outdoors as much as possible when the UV index is very high or extreme.
In infants under six months, it is recommended consult the pediatrician Before applying any type of sunscreen, prioritize physical protection through light clothing, a hat, and constant shade. From that age onward, the use of high SPF creams adapted to sensitive skin, along with long-sleeved clothing and sunglasses with UV protection, is considered the best possible combination.
People with very fair skin, history of severe sunburns, family history of melanoma Those with conditions that increase photosensitivity should take even greater precautions. In their case, it may be advisable to completely avoid outdoor activities during peak photosensitive hours, even when using standard protective measures.
For groups such as the elderly, patients undergoing treatments that sensitize the skin to the sun, or those suffering from eye conditions, daily monitoring of real-time UV index Using weather services or reliable apps is a useful tool for planning your day wisely.
The role of companies and administrations in prevention
Workers who spend many hours outdoors depend heavily on the working conditions established by companies and administrations. Occupational health recommendations include organizing the most demanding tasks outside of peak radiation hours, scheduling frequent breaks in the shade and facilitate continuous access to drinking water to maintain adequate hydration.
It is also considered good practice for the employer to provide protection equipment Such as wide-brimmed hats or caps, breathable long-sleeved clothing with some degree of UV protection, certified sunglasses, and, when necessary, sunscreen for frequent use. These measures, although they may seem like a minor detail, significantly reduce the cumulative exposure of the staff.
Health and meteorological authorities, for their part, play a key role through the dissemination of alerts When very high or extreme UV index episodes are predicted, integrating these warnings into the usual information channels—websites, social media, mobile applications, or news outlets—helps the public incorporate the information into their daily routine, just as they do with temperature or the probability of rain.
Furthermore, awareness campaigns on skin cancer prevention They emphasize the importance of regular checks of moles and spots, consulting a dermatologist about any suspicious changes, and not underestimating sunburns, even if they appear to heal in a few days. The combination of information, protection, and early detection remains the best strategy for reducing the impact of UV radiation on health.
The increasing frequency of episodes with Very high or extreme UV index This indicator has become an essential reference point when planning outdoor activities. Checking the forecast, adjusting schedules, seeking shade, wearing appropriate clothing, sunglasses with UV protection, and broad-spectrum sunscreen, as well as paying special attention to children, vulnerable individuals, and exposed workers, allows you to enjoy the sun with greater peace of mind and minimize a risk that, although not immediately visible or noticeable, leaves its mark on the skin and eyes over time.
