A UV sterilization lamp in a kindergarten tanned all the children in one class
Some lamps, like the sun, can also tan and burn you
□ Times reporter Jiang Dawei, Wang Yanwen
Intern reporter Xu Bingbing photographer Lin Yanting graphic designer Huang Chunyan correspondent
When her daughter Tian Tian's (a pseudonym) skin gradually darkened, citizen Ms. Lu did not pay much attention at first. However, during one of her visits to pick up her child from kindergarten, she was shocked by what she saw: more than ten children in Tian Tian's class were as dark as if they had just returned from Africa, and each one was darker than the last. Meanwhile, children from other classes remained fair-skinned and rosy. What was going on?
The constantly-on sterilization lamp
Tanned the entire class of children
Ms. Lu took Tian Tian to Hangzhou Third People's Hospital, where Deputy Director Song Weimin of the Dermatology Department immediately knew that Tian Tian had been tanned by ultraviolet (UV) rays. Subsequently, Tian Tian's classmates, accompanied by their parents, also found Dr. Song, and the diagnosis results were the same as Tian Tian's.
Ms. Lu contacted the parents of several other children and together they went to the kindergarten in Hangzhou where her daughter attended. However, the kindergarten staff were also puzzled because from 8 am to 4 pm every day, except for a 20-minute morning exercise session outdoors, the children spent most of their time indoors. So how could they have been tanned by UV rays?
All the parents were baffled until a detail casually revealed by a kindergarten teacher led Dr. Song to find the culprit - a UV sterilization lamp installed in the classroom.
According to regulations, the UV sterilization lamp in the kindergarten classroom should only be turned on for about an hour each day. However, due to the teachers' unfamiliarity with the operating procedures, the UV sterilization lamp in the classroom remained on continuously. Over time, excessive UV exposure darkened the children's skin.
Nightclub-loving beauties
Tanned at night by spotlights
With summer approaching, effective sun protection has once again become a topic of great concern. However, some cases from the dermatology outpatient department of Hangzhou Third People's Hospital indicate that it is not only sunlight that can tan or even burn the skin; various indoor lights can also do so, and some people even get tanned at night.
"Cases of being tanned or burned by artificial lighting are actually quite common, and those dozen children are not isolated incidents," said Dr. Song Weimin, a dermatologist who has handled many such cases. One young woman paid special attention to sun protection during the day but still got tanned. Upon inquiry, it was discovered that she loved going to nightclubs and was tanned by the UV rays emitted from the high-power spotlights there.
In addition, some female broadcasters from television stations frequently visited Dr. Song. Each time they finished recording a program, their skin would start to turn red, gradually becoming darker and deteriorating. The culprit here was also the various lights shining on their faces daily in the studio.
Two types of UV wavelengths
Most easily damage human skin
Why can artificial lighting tan or even burn the skin? First, you need to understand UV rays.
Professor Lu Xuanhui, deputy director of the Institute of Optics at Zhejiang University, explained that UV refers to electromagnetic radiation with wavelengths ranging from 100nm to 400nm. Among them, wavelengths between 100nm and 200nm are vacuum UV (UV-D), wavelengths between 200nm and 280nm are short-wave UV (UV-C), wavelengths between 280nm and 315nm are medium-wave UV (UV-B), and wavelengths between 315nm and 400nm are long-wave UV (UV-A).
The wavelength of UV is inversely proportional to its energy. The longer the wavelength, the stronger its ability to penetrate the skin. The shorter the wavelength, the stronger the energy, making it more likely to cause skin lesions.
UV-D cannot effectively propagate in the air, while shorter-wavelength UV-C is almost completely absorbed by the ozone layer. Therefore, the main UV rays from natural sunlight are UV-A and UV-B, with UV-A accounting for approximately 98.1% and UV-B accounting for 1.1%.
"UV-A can penetrate the epidermis and reach the dermis, affecting the melanin in the skin's epidermis, leading to melanin deposition and darkening of the skin," Professor Lu Xuanhui explained. "On the other hand, UV-B hardly penetrates the epidermis, but prolonged exposure to higher-energy UV-B can cause photodermatitis, resulting in redness, itching, blisters, and swelling on the skin. Excessive UV exposure can also lead to skin cancer."
Some lamps emit UV
Halogen lamps not recommended for home use
Let's revisit the UV sterilization lamp at that kindergarten. To achieve optimal sterilization effects, the wavelength of the UV sterilization lamp is usually set at 253.7nm, which belongs to the strongest energy UV-C band. It’s no wonder then that the children were tanned.
"Some types of lighting can also release UV rays, and depending on the type of lamp, power, color, and manufacturing process, the intensity of UV radiation varies," said Deputy Director Song Weimin of the Dermatology Department at Hangzhou Third People's Hospital. "Especially those high-power metal halogen lamps, which release medium and long-wave UV rays similar to those released by sunlight, can damage the skin."
Professor Lu Xuanhui from Zhejiang University also pointed out that many public places such as bars, restaurants, shopping malls, and stadiums often use lamps with strong UV radiation. These radiated UV wavelengths range from approximately 300nm to 400nm, falling within the medium and long-wave UV bands, which significantly impact human skin.
"Many people now like to use metal halogen lamps to decorate their homes during renovations, some even installing them in bedrooms. Although these lamps are bright and aesthetically pleasing, prolonged exposure can have considerable effects on humans," Professor Lu Xuanhui mentioned.
Lamp UV radiation intensity
No safety quantification standards yet
Although the UV rays emitted by artificial lighting can tan and burn the skin, Professor Lu Xuanhui stated that currently, there are no safety quantification standards in China regarding the UV radiation intensity of lamps. However, the degree of harm caused by lamp UV to the human body depends on various factors, such as the performance of the lamp, distance from the human body, and duration of exposure.
Among the lamps we commonly come into contact with, apart from special lamps like metal halogen lamps, UV sterilization lamps, and UV insect traps having relatively high UV radiation intensity, ordinary incandescent lamps do not produce UV rays.
For fluorescent lamps and energy-saving lamps, although their working principle involves emitting heat electrons through electrodes to excite mercury atoms to release UV rays, after the UV rays pass through the fluorescent powder coated on the inner side of the lamp tube and convert into visible light, only a trace amount of UV-A wavelength UV rays are emitted, which will not significantly affect the human body.
People who work under lamps with higher UV radiation for extended periods or are too close to the lamps are more likely to suffer skin damage, such as salespeople in malls, waiters in restaurants, and TV anchors. However, for the general public, as long as they do not stay under these lamps for too long or avoid direct exposure or close contact, there is generally no need for excessive worry.
How to combat UV rays
Should you apply sunscreen every 15 minutes like famous artist DaS?
Hangzhou Third Hospital expert: This concept is worth learning
There are UV rays in sunlight, and some artificial lighting also contains UV rays. In the face of omnipresent UV rays in life, how should we protect our skin? Should we follow the advice of famous artist DaS in "Beauty Bible" and reapply sunscreen every 15 minutes to ensure that our skin is not harmed?
Deputy Director Song Weimin of the Dermatology Department at Hangzhou Third Hospital said that although applying sunscreen every 15 minutes might seem exaggerated and impractical, this concept is worth promoting because the awareness of UV protection among Chinese nationals is still relatively weak.
Excessive UV exposure
Can easily trigger skin diseases
Statistics show that Hangzhou Third Hospital diagnoses nearly a thousand skin cancer patients each year, and this number is increasing annually.
"Compared to Caucasians, Asians have a slightly lower incidence of skin cancer and skin diseases, but compared to UV protection measures, we are still relatively lacking," Director Song said. Many skin diseases are related to excessive UV exposure.
"Moderate daily sun exposure can supplement calcium and benefit the body, generally 15 minutes per day is sufficient. However, if exposed to excessive UV rays, it can harm the skin," Director Song said. In addition to tanning and burning the skin, UV rays can also accelerate skin aging.
Physical sun protection is more reliable
Reapply every two to three hours
Besides using umbrellas and clothing to protect against UV rays, Director Song believes that correctly using sunscreen products is also necessary, and these protective measures are not exclusive to women; men should emulate them.
"Currently, there are mainly two types of sunscreens available on the market: physical and chemical. The former has relatively better sun protection effects and can effectively resist most UV rays damaging the skin, but the downside is that these sunscreens tend to clog pores," Director Song explained.
The other type is chemical sunscreen. Using this type of sunscreen makes the skin feel relatively fresher, but compared to physical sunscreens, its effect is much weaker. Moreover, after using chemical sunscreen, it generally takes half an hour before it becomes effective; otherwise, it will not provide any sun protection or UV resistance.
Regarding DaS's practice of applying sunscreen every 15 minutes, Director Song believed that while it might be somewhat exaggerated, the common habit of applying sunscreen in the morning and not reapplying throughout the day is even less advisable. The correct frequency of using sunscreen products is to reapply according to the environment every two to three hours to achieve effective protective effects.
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