SunburnIt is a symptom of skin damage caused by excessive exposure to the sun. If you stay outdoors for a long time on a sunny day, exposing a lot of body skin is very dangerous, because clouds do not always block the sun. Severe sunburn on the first day of the sun and beach vacation can ruin the rest of your vacation.
learn
When traveling, especially staying outdoors for a long time, you should take adequate sun protection measures. Never underestimate the power of the sun at noon in the tropics and mountains, even in ordinary summer. Skiing is very dangerous, because in addition to direct sunlight, your body will also be exposed to sunlight emitted from a smooth white surface. Similarly, water and sand can also reflect sunlight.
Ultraviolet rays are the main threat to solar radiation. These short-wavelength photons have higher energy than the visible part of the spectrum, so they cause greater damage. Ultraviolet rays cannot be seen by the naked eye, but it can penetrate light to moderate clouds and some clothing, so it is difficult for you to judge how much radiation you have absorbed. It is better to be careful.
Unfortunately, the "ozone hole" formed by pollutants in the upper atmosphere can allow more ultraviolet rays to reach the ground than before, so the danger of polar regions (under the ozone hole) has increased in recent years. It is not yet clear how far this threat extends in the polar regions, and this threat will change over time, so people who spend a long time outdoors in high latitudes should take sun protection measures.
In addition, sunburn and long-term exposure to too much sunlight can induce skin cancer. Basal cell carcinoma and squamous cell carcinoma are not too bad, but they leave unsightly scars after removal. However, melanoma is as deadly as other serious cancers. It has gradually become known over the past few decades that sunburn can greatly increase the risk of melanoma.
How does the risk increase
Your sensitivity to sunburn depends largely on your skin tone. People with red hair, blue eyes, and freckled skin are at the highest risk of skin damage. In spring, before getting used to the stronger light (and likewise, before getting used to the stronger sun at the destination), the risk will also increase.
When the sun in the sky is high, the risk of sunburn also increases (see belowUV index). Taking certain medicines can also increase the risk of sunburn. Certain antibiotics, contraceptives, sedatives, and malaria prevention drugs make people very sensitive to sunlight. Leaving lemon juice or other citrus juices on the skin will increase the speed and intensity of sunburn.
In recent years, the incidence of sunburn has been increasing globally, especially in the southern hemisphere, because the ozone layer is destroyed by CFCs.
UV index
WHODefined UV index
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Ultraviolet (UV) index is an international standard, which points out the intensity of sunlight in a day and the potential threats it brings. The higher the index value, the greater the risk of sunburn.
At present, more and more meteorological departments and local newspapers provide their predicted future UV index values. However, be aware that if you travel to underdeveloped countries, you will not find this information. Therefore, the best way is to get the latest information before setting off. You can get UV index forecasts around the world on many websites.
The intensity of ultraviolet radiation is affected by the following seven factors:
The angle of the sun
- latitude——The sun in the tropics is the hottest, especially in the northern tropics from March 21 to September 21 and the southern tropics from September 21 to March 21 of the following year.
- season——The sun is strongest in sunny weather during the summer solstice. As many areas are overcast during this period, the peak may be pushed back.
- Time of day——It is the strongest in the daytime from 9 am to 3 pm, and the peak occurs at 12 noon. Solar time (solar time) can be more or less reflected in the local time, but the local time is a political matter, it may even deviate from the solar time by a few hours. When using daylight saving time, postpone it by one hour (that is, 10 am to 4 pm).
The above three factors can be combined into a simple measurement. When the sun is at 45º in the sky, the rays are strongest. In other words, your shadow is shorter than your actual height, and a short shadow means higher UV intensity.
For mathematics enthusiasts, at noon at latitude L, the general law of the angle of the sun deviating from vertical is as follows:
- The angle is L: the equinoxes in March and October anywhere.
- The angle is L-23º: on the summer solstice in your hemisphere. It is June 21 in the northern hemisphere and December 21 in the southern hemisphere.
- The angle is L 23º: the winter solstice, the time is the opposite of the above.
The angle in tropical areas is sometimes 0, L≤23º, that is, L-23º≤0º≤L 23º. The sun between the Tropic of Cancer (23ºN) and the Tropic of Capricorn (23ºS) sometimes shines directly.
The midnight sun will appear in areas where L≥67º, where L 23º is sometimes greater than 90º, and the sun at the winter solstice is below the horizon even at noon. In summer, its sun is on the horizon even at midnight. However, outside the polar circle with the midnight sun, the sun intensity is generally very low, so except for people with allergies, most people can stay outdoors all day long (but snowy days reflect multiple levels of sunlight, and high altitude areas require careful).
envirnmental factor
- altitude——Ultraviolet radiation increases rapidly with altitude.
- weather——The strongest days are sunny days without precipitation, and thin clouds cannot provide protection.
- environment——Sand, water, and snow reflect ultraviolet radiation into the shade, and can evade protection such as hats or parasols. So you not only received ordinary sunlight, but also reflected light.
- Ozone layer-The atmospheric ozone layer provides some protection against ultraviolet radiation, but its thickness will vary. The ozone layer near the poles in spring is generally thinner, which means that the radiation is stronger than in temperate regions. The "holes" in the ozone layer are irregular.
Ultraviolet A and Ultraviolet B
The sun emits three types of ultraviolet radiation. Since UV-C cannot penetrate the earth's atmosphere, it is not a problem. UV-B is something that most people think of causing sunburn. It has a short wavelength and only penetrates the surface layer of the skin (ie epidermis), so the surface layer absorbs all UV-B energy and causes all damage. In addition to causing redness and pain, UV-B can also directly damage the DNA of the skin and is considered the most dangerous type of UV radiation. UV-A penetrates deeper into the skin and does not cause immediate visible damage, but causes long-term skin damage.
When buying sunscreen, you can’t just consider the type that protects you from UV-B radiation. Exposure to any kind of UV radiation increases the risk of skin cancer.
Summer solstice
The summer solstice is the strongest day of the sun and is sometimes referred to as the first day of summer. The summer solstice in the northern hemisphere is June 21 and in the southern hemisphere is December 21. In addition to the tropics, the UV of the summer solsticeRadiation levels are highest throughout the year. Of course, the atmosphere has not yet had time to fully warm up to the highest temperature in summer, and many places are still cloudy and cool. However, if it happens to be sunny, you need UV protection most at this time. The earth tilts its axis completely to 23.5 degrees on the summer solstice, irradiating tropical-like UV to temperate regions.
- All places in the tropics have direct sunlight twice a year. In the sense of a year, the tropics receive the same amount of UV radiation as the equator (assuming the same environmental factors).
- Temperate regions (up to 47 degrees latitude) receive more UV radiation than the equator during the summer solsticemany。Italy、new ZealandwithAmericaAlmost all of the east is below 47 degrees. In the West, the border between the United States and Canada is 49 degrees.
- The UV radiation between 47 degrees and the polar circle is equal to the amount absorbed during the summer solstice in tropical regions on the other side of the equator (winter time). ifIcelandReykjavikIf June 21st is sunny and sunny, it will absorb more ultraviolet rays thanRio de JaneiroSlightly stronger, this is because Reykjavik is closer to the Tropic of Cancer at 23.5 north latitude than Rio.
Fortunately, with the passage of summer, the axis of the earth moved to coincide with the equator again. The real danger is that around the summer solstice, people with fair skin who have not been exposed to the sun for a few months will spend time going out without protection. They may mistakenly think that UV radiation is not that bad, but in fact, it is very bad.
Safeguard
Before departure, try to understand the climate conditions of the area you are visiting, especially the information about sunlight and solar energy.WHOA rough average UV index value table will be drawn for some cities around the world, but you should always check the current information. In addition, inSunburnmap websiteYou can check the current UV index anywhere in the world, and the station also has forecasts for the next two days.
When you arrive at your destination, especially if you are used to low sun intensity before, going directly to the beach or walking lightly in the midday sun for three hours is something you will regret at bedtime. It takes a few days for your skin to adjust to the new intensity of sunlight. Therefore, please follow the recommendations below:
Sunglasses
 | Notice:Wearing sunglasses without UV protection is more harmful to your eyes than not wearing sunglasses, so make sure that your sunglasses are from a reputable, UV-certified brand. |
In bright sunlight, especially in environments that reflect sunlight, such as beaches, glaciers and deserts, sunglasses are a necessity.
Make sure that your sunglasses do not leave a gap in the line of sight: if you look down, although you can see through the sunglasses, your eyes will still receive ultraviolet radiation. In high-intensity UV environments, such as high altitude areas, ski goggles are needed instead of sunglasses.
Although counterintuitive, buttransparentorLight colorSunglasses thanDark colorThe protection provided by this is better, because firstly, your instinctive aversion to the sun is retained, and secondly, your pupils will remain constricted and less light enters the eyeball.
clothing
Clothes are the most effective protection against the sun to a large extent, but not all clothes are UV-proof. You may still get sunburned despite wearing some clothes.
Traveling in a tropical environment, DaiBig hatorscarf,Put onThick cottonWhite or beigeLong-sleeved shirt and trousers. Avoid wearing T-shirts and shorts; you can wear long-sleeved and very loose-fitting clothes that are as cool and can avoid sunburn. The back of the neck is prone to sunburn, so the jacket should have a collar and the collar should be turned upright (or wear a cotton scarf). Moreover, in order to protect the face, especially the forehead, you can wear a hat or baseball cap, and try to wear shoes and socks.
existbeachYou should not take off your coat except for swimming. Of course, in this case, you should not stay in the water for too long. Consider wearing sun clothes in the water. If you feel that full clothing is contrary to the purpose of coming to the beach, use thickSarongWrap yourself in only a bathing suit.
Consider bringing a small fold that has a large sunshade area and a small fold that is smaller than a hatumbrella. This is a standing product for tropical sun protection in Asia.
behavior
Don't stay outdoors for too long at noon without extra protection, especially when traveling in tropical areas. Block out the sun as much as possible. If possible, try to arrange protected outdoor activities such as swimming or boating in the early morning or evening.
Sunscreen
It is better to have sunscreen lotion than not, but you have to know: even the highest factor sunscreen lotion can only provide partial UV protection (although the label says "full UVA/B effective"), and it is exposed to strong sunlight for a long time (more than two hours) ) Are invalid.
Sunscreen milk is rated according to the Sun Protection Factor (SPF), which measures the degree of burn reduction. For example, if you get a sunburn without protection for 10 minutes, with SPF 15, you should be able to get 150 minutes before you get sunburned. This is not a definite number; many factors will affect the effect: how thick the coating is, different countries have different standards for SPF labels, SPF labels generally ignore UVA, which does not cause redness and pain but can cause other damage. Recent studies have shown that an SPF value that is considerably higher than 30 also provides no more protection than 30.
Sunscreen lotion should be thoroughly applied to areas that cannot be covered by clothing, such as the face, back of hands and any exposed skin. The sunburn on the instep and the back of the knee was surprisingly fast. If you plan to stay in the water, you can use a waterproof sunscreen lotion. In order to work effectively, the lotion needs to be reapplied every two hours, when entering water or sweating. No matter what sunscreen product is, make sure it is "fresh". Even the best formula will start to lose effectiveness after more than a year.
deal with
If you are sunburned, erythema will appear at first, followed by varying degrees of pain, the severity of which is proportional to the duration and intensity of the exposure. After being sunburned, the skin may turn red after 2 to 6 hours, and pain is the most severe after 6 to 48 hours. Sunburn will continue to develop for 24 to 72 hours. Skin peeling will begin 3 to 8 days after sunburn. Common symptoms include tenderness, pain, edema, redness and/or peeling, rash, nausea, and fever. Sunburn can be a first or second degree burn.
Minor sunburns generally only cause redness, swelling and tenderness in the affected area. Even worse, it may blisters. A severe sunburn can be painful to the point of causing fatigue and may require hospitalization. Severe sunburn, please seek medical attention as soon as possible.
Diving in open water will not help relieve the symptoms of sunburn, but will damage your skin. If your skin blisters, beware of infection. Take a cold shower (not cold water) or soak in a bath. Avoid scrubbing or shaving, and use a soft towel to dry your body.
Using the company's after-sun cream or aloe vera extract can relieve the current symptoms. You may also consider taking painkillers to relieve the redness and pain caused by sunburn. For particularly painful areas, steroid ointments can be applied; however, you should not apply topical anesthetics, as they may exacerbate the symptoms. According to some people’s experience, using lavender oil or plain yogurt on the wound surface may cause pain.
Try torestadequate,drinkPlenty of water prevents dehydration. Please avoid the sun until the skin recovers, it usually takes about a week.
Heatstroke
Heatstroke is a general term for symptoms caused by an abnormal rise in body temperature, which is a serious life-threatening condition in which the human body loses its ability to self-regulate body temperature. The warming of the human body can make the patient very uncomfortable.
Of course, high temperature is the main cause of disease. But humidity is also a very critical condition: high humidity, slow evaporation of water, and sweating of the human body to cool down by itself is not very effective. Your sweat can cause dehydration. You should always add a lot of water in hot weather. Any physical exertion can cause heat stroke.
The following are different situations of heat stroke:
| Fever | Thermal fatigue | Heat cramps | Heat stroke | |
|---|---|---|---|---|
| consciousness | disappear | normal | normal | Height barrier |
| body temperature | normal | ～39℃ | normal | Above 40℃ |
| skin | normal | cold | normal | high temperature |
| sweat | （＋） | （＋） | （＋） | （－） |
