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About ultraviolet ray and skin, eyes

Last update date November 12, 2019


In Japan, it is season when ultraviolet ray (UV) is strong over early fall from spring. What ultraviolet ray bathes in too much adversely affects health. Ultraviolet ray is strong; from April through September of ultraviolet ray let's be careful to bathe too much.
In addition, it requires attention depending on surrounding in season of igai from spring to early fall. For example, in winter season, the surface of the snow of one side is strong in reflection of ultraviolet ray. Activity in the surface of the snow of one side might produce snow-tan or snow blindness (yukime: the ultraviolet ray inflammation of the cornea) that sunburn does not become by reflection of ultraviolet ray, and ultraviolet ray measures such as sunglasses are necessary.

What is ultraviolet ray?

Ultraviolet ray is a part of the sunbeam (Nikko). Ultraviolet ray is one of the rays that we cannot feel as light with eyes with infrared ray. Visible ray is ray that we can feel as light with eyes, and wavelength is 400-770nm. In addition, nm (nano meter) is unit of length, and 1nm is 1 per 1 billion meter. Wavelength around 400nm of visible ray is purple, and wavelength around 770nm is red. Infrared wavelength is with 400nm or less of wavelength of ultraviolet ray 770nm or more. Ultraviolet ray (UV: ultraviolet) based on difference in biological influence by difference in wavelength by wavelength of light UVA (ultraviolet A: A domain ultraviolet ray, long wavelength ultraviolet ray, wavelength 320-400nm), UVB (among: B domain ultraviolet ray ultraviolet B wavelength ultraviolet ray, wavelength 290-320nm) of UVC (: C domain ultraviolet ray ultraviolet C, short wavelength ultraviolet ray, wavelength 200-290nm) is distributed between three kinds. In addition, about classification by wavelength of ultraviolet ray, there are 100-280nm and classification to do in 280-315nm, UVC in 315-400nm, UVB in UVA suggested first at the second international rays meeting of 1932.
Please see figure 1 below.

Difference in stratosphere ozone layer transmission by ultraviolet ray wavelength

UVA passes the stratospheric ozone layer in altitude from 10 kilos to 50 kilometers among ultraviolet ray included in sunbeam (Nikko) from the surface of the earth, and part of UVB passes and arrives at the surface of the earth (about 90% arrive at UVA. It does not arrive at the surface of the earth without UVC passing whereas about 10% do UVB arrival). For ultraviolet ray measures caused by sunbeam (Nikko), UVA, measures for UVB are necessary. In addition, on ground, outbreak of UVC is seen from the welding arc lamp or germicidal light.
UVB reaching the surface of the earth becomes weak so as to be long about UVB if distance to pass the stratospheric ozone layer is long. Please see figure 2 below.

Difference in distance to pass the stratosphere ozone layer of sunbeam by position of the sun

UVB to receive at Point D weakens when we compare UVB which UVB and the sun to receive at Point A where the sun is right above head receive at Point D seen at low position as distance to pass the stratospheric ozone layer is long at Point D. Point A becomes to watch out about ultraviolet ray when we compare Point D with Point A. In Point A, Point D is morning and evening around noon if we see during one day. In Point A, in tropics, Point D of the neighborhood of equator, it is in the cold polar region near the North Pole and the South Pole if we see at latitude of the earth. In Point A, (around June 22), Point D are (around December 22) in winter solstice in the summer solstice if they see in season. In addition, at altitude, high place receives strong ultraviolet ray from low place. Whenever altitude rises by 1,000 meters, UVB 10-12% increase.
Reflectance of ultraviolet ray in planes such as earth surfaces varies according to the composition, and it is 1.6-0.8% with 6.0-4.0%, lawn with 3.3%, soil in 6.6%, sea foam design of turbulent waves with 88.0-50.0% (fresh snow is higher), white paint of house by snow on 5.0-2.0%, meadows on 8.0%, the surface of the water at 30.0-25.0%, the sea surface at 9.1%, deck of wooden ship at 4.1%, deck of fiberglass ship made on 8.9%, black new asphalt paved road on 12.0-8.2%, gray old asphalt paved road on 7.1%, the concrete sidewalk on 18.0-15.0%, wet sandy beach on 22.0%, dry sandy beach (references 14). It is necessary to be careful about reflection of ultraviolet ray at place where snow, sand, white wall, concrete, asphalt are frequent in the neighborhood. At place with many reflections, ultraviolet ray may about half just weaken in degree under parasol and awning. We do on the coarse surface more softly than the smooth surface firmly and can expect that we weaken reflection by invention such as doing for the painting that there are few reflections. In addition, cloud blocks Nikko to some extent, but does not block ultraviolet rays enough. About 20-40% of ultraviolet ray just weakens on cloudy day.
UVA transmits to the depths of skin and greatly participates in aging of skin. Among changes of skin seen by aging such as wrinkles well, it may be related even to 90% to bathe in Nikko. Transmission to skin is light, and UVB has a big influence on the skin surface. UVB is main causes of sunburn (sunburn that is red Sambourne sunburn). In late years the stratospheric ozone layer becomes thin, and it is known that UVB reaching the surface of the earth is strengthened under the influence of release of Freon. Reinforcement of regulation in global environmental aspect is accomplished, but time suffers so that the stratospheric ozone layer recovers according to the cause, and take approximately 50 years; is turned on.
In addition, windowpane does not permeabilize almost all UVB and does not permeabilize at least half of UVA.
In addition, there is property such as there not being the toxicity not to burn that Freon is chlorine and carbon, generic name of compound made of fluorine and does not change in quality, including cleaning of foaming, semiconductor of refrigerant, insulation materials such as jet agent, air-conditioner or refrigerator of spray have been used widely. However, it just rises to the stratosphere without being broken in the atmosphere of neighborhood above the ground when Freon is released and it bathes there in ultraviolet ray (UV-C) and is broken. Freon releases chlorine atom, but it is said that this destroys ozone for chain reaction on this occasion. It is said that one chlorine atom destroys tens of thousands of ozone when it is a lot.

Influence on skin ... of ultraviolet ray

Sunburn (sunburn that is red Sambourne sunburn) and erythema (blush)

We cause expansion of blood vessel of skin and as blood volumes in skin increase, irradiation of Nikko to skin turns red, and form erythema. Erythema develops after the irradiation of ultraviolet ray in 3-5 hours and it becomes most remarkable and we attenuate for approximately three days and disappear 8-24 hours later. It may become in a state such as burn without remaining in erythema when irradiation of Nikko is superabundant. Inflammation is caused and forms blister, and skin may peel off. We are reduced to some extent if we think that we tanned by sea bathing too much when we cool with cold water towels as soon as possible.

Melanism (sunburn that becomes black, and is black suntan tanning, suntan) of skin

It is defense reaction of the human body to become black by irradiation of Nikko to skin. It is caused by UVA and some visible rays, and immediate type begins in the middle of irradiation of Nikko to skin and becomes blackest as of the end of irradiation, but becomes thin afterwards with progress at time. Immediate type is not accompanied by generation of melanin. Late-onset form becomes peak beginning, 7-10 days later 48-72 hours after irradiation of Nikko to skin. It may be black for several months from several weeks. Late-onset form is accompanied by generation of melanin.
We irradiate UVA mainly, and, in tanning salon, black sunburn (suntan) is caused. The sunburn apparatus is also called tanning machine. However, on the other hand, UVA gains stains of skin and may push forward aging of skin. It is thought with effect that SPF (sun protection factor) has weak sunscreen and same class from 2 to around three for preventive effect of red sunburn (Sambourne) caused by black sunburn (suntan) to be provided in tanning salon. In addition, incidence of malignant melanoma was higher with 2.58 times than woman who woman who went to tanning salon more than once a month to 20s was in her twenties by Norway and research (references 10) for Swedish women, and did not go in tanning salon at all. In addition, example that by receiving large quantities irradiation in tanning salon, bakes, but was in a condition is reported to National Consumer Affairs Center of Japan to be able to have red sunburn although being poor at UVA.

Skin cancer (NMSC: Nonmelanoma Skin Cancer) except malignant melanoma

As a result of revelation to long-term sunlight, skin cancer (basal cell carcinoma, squamous cell carcinoma) except malignant melanoma may be seen. 90% or more of skin cancer except malignant melanoma with UVB it is thought that is related. In the United States, basal cell carcinoma occurs in 1 million or more in the year, and squamous cell carcinoma occurs in higher than 200,000 in the year. It often occurs in part getting sunlight of people of skin of white, and there is little outbreak in people of black skin. We are rarely tied to death if we cure.
In addition, death due to skin cancer except malignant melanoma in Japan of 2001 is 564 people, and, according to the vital statistics (Ministry of Health, Labour and Welfare), 0.19% of all cancer death, the death due to malignant melanoma of skin are 0.17% of all cancer death with 500. Death due to skin cancer is 1,064 people a year, and 0.35% of all cancer death, the death rate of a population of 100,000 pairs are 0.8 when they add up. About the number of the incidence of skin cancer in Japan, there are 6,844 people a year by estimation (references 4) of 1998, and annual prevalence is 5.4 with a population of 100,000 pairs.
In addition, patients with skin cancer except malignant melanoma produce 2 million-3 million people throughout the world in the year. When 10% of stratospheric ozone decreases according to the guess of United Nations Environment Program (UNEP), it is thought that the number of the patients with skin cancer generating except malignant melanoma further increases 300,000 a year throughout the world.
In addition, according to the guess of World Health Organization (WHO), the death toll for skin cancer except malignant melanoma which takes too much, and stops by of ultraviolet ray in the whole world may amount to 12,000 a year.

Malignant melanoma

Cell creating brown pigment called melanin (melanin) is melanocyte (melanocyte). Skin cancer which occurred from melanocyte is malignant melanoma. In the United States, more than 50,000 outbreak is seen in the year. Malignant melanoma accounts for 80% or more of deaths due to skin cancer in the United States. It is thought that it is related to outbreak of malignant melanoma to take sunlight in large quantities in a short term. Malignant melanoma has less outbreak than skin cancer except malignant melanoma, but in late years increases clearly in the United States. In the United States, possibility to become malignant melanoma during life increases with 1 of 120 people in 1 of 250 people, 1987 in 1 of 1,500 people, 1980 in 1930. About increase of malignant melanoma in the United States, it may be related that in late years ultraviolet ray reaching the surface of the earth increases or that in late years clothes that there is much exposure of skin come to be favored. There is much outbreak in whites with about 10 times of outbreak in blacks. The death rate due to malignant melanoma of white is about 5 times of the death rate due to malignant melanoma of black. Melanin of skin reduces transmission of ultraviolet ray in skin. Malignant melanoma is more likely to be saved by treatment (surgical resection) if discovered early, but thing which caused metastasis often results in death. In the United States, as for the thing which spread to lymph node, as for the thing which metastasized to remote organs such as 30-40%, liver, bone, brain survival rate for five years, survival rate is 12% for five years. About malignant melanoma, the prevention and early detection, early treatment are important.
In addition, patients with malignant melanoma produce 132,000 people throughout the world in the year. When 10% of stratospheric ozone decreases according to the guess of United Nations Environment Program (UNEP), it is thought that the number of the patients with malignant melanoma occurrence further increases 4,500 a year throughout the world.
In addition, according to the guess of World Health Organization (WHO), the death toll for malignant melanoma which takes too much, and stops by of ultraviolet ray in the whole world may amount to 48,000 a year.

Aging of skin

By continuing taking ultraviolet ray without sunscreen, a lot of wrinkles are deepened, and skin becomes inelastic, and stains will increase.

Recurrence of herpes labialis

For herpes labialis, human herpesvirus 1 (HSV-1) mainly produces blister (blister) and ulcer to mouth and lips for at the time of cold or high heat. In Europe and America, 80-90% of adult have antibody of human herpesvirus 1 (HSV-1), but it is said that 18-32% of those cause recurrence of herpes labialis. Of emotional stress, disease, injury, sunlight (ultraviolet ray) is said that take too much, and equal gakikkaketonatte, recurrence of herpes labialis may be seen.
Please refer for this Yokohama City Inst. of Health homepage infectious disease information "sexual organs herpes infectious disease".

Influence on eyes of ultraviolet ray


Ultraviolet ray lets cataract to be seen with aging progress. There are many cataracts so that there is much sunlight that latitude is exposed to soon low in the equator, and there is much UVB. Cataract is the first place of cause of loss of eyesight when we see worldwide (we refer for our Yokohama City Inst. of Health homepage infectious disease information "trachoma (trachoma)").
In addition, it is thought that the number of the patients with cataract generating further increases 1.6 million-1.75 million a year throughout the world when 10% of stratospheric ozone decreases.

The ultraviolet ray inflammation of the cornea

It is inflammation of acute cornea caused by strong ultraviolet ray. Reflection of ultraviolet ray in the surface of the snow is strong, and the inflammation of the cornea called "snow blindness" (yukime: snow blindness) may be caused. When sandy beach, dune, desert, waterside, reflection of ultraviolet ray including concrete side are strong, not only the surface of the snow, it is necessary to wear sunglasses, and to be careful. In addition, we call the inflammation of the cornea, conjunctivitis to be caused by arc welding light by occurring ultraviolet ray electricity-related ophthalmitis. It is necessary that worker performing arc welding, blowout work puts shading protection aspect, dust protective mask for welding and works. We are exposed to ultraviolet ray and often become sick for a feeling of alien substance, ache in the eye, lacrimation of eyes, conjunctiva hyperemia after several hours or more.


Disease that fibrous tissue multiplies from bulbar conjunctiva (the white of eyes) and invades wing-like on cornea (iris of the eye). We are seen in 30s or more, and progress is not usually early. When invasion advances to pupil neighborhood, visual disorder is caused. For treatment, we remove surgically surgically. Activity in the open air is common in many people, and revelation to ultraviolet ray is thought about with one risk factor of pterygium.

To prevent ultraviolet ray; ...

Ultraviolet ray measures in particular are necessary for a long time when we take sunlight outdoors, and sunburn is possible. Let's be careful about the following things to prevent ultraviolet ray.

  1. Let's avoid sunlight of noon as much as possible.
    During 2:00 p.m. is strong in ultraviolet ray of Nikko from 10:00 a.m. Let's avoid sunlight in particular as much as possible between 10:00 a.m. and 2:00 p.m.
  2. Let's put on sunglasses intercepting ultraviolet ray more than 99%.
    We put on sunglasses intercepting ultraviolet ray causing cataracts more than 99%, and let's protect eyes. If it is form such as goggles, ultraviolet ray from vertical and horizontal space of lens can prevent, too.
    In addition, lens that block of ultraviolet ray is insufficient just to be strong is dangerous. Quantity of ultraviolet ray to get into in eyes because we feel to be gloomy, and pupil opens may increase.
  3. Let's put on hat. Let's use parasol.
    Edge is large, and let's put on hat keeping the next of eyes, ear, face, neck from ultraviolet ray. Baseball cap that only one has relationship is not suitable. Parasol is effective for shutting out direct rays of the sun, too.
  4. Let's stay in shadow.
    What we remain in in shadow of thing which cuts off Nikko, and makes shadow is one method not to bathe in Nikko directly.
  5. Let's wear long sleeves, pants.
    We reduce exposure of skin, and let's protect skin from ultraviolet ray. Pants have better long skirt than miniskirt than shorts shirt with collar (collar) with long sleeves than tank top.
  6. When we appear outdoors, let's paint skin with sunscreen.
    Let's paint with sunscreen with high value and PA classification (protection grade of UVA) of SPF (sun protection factor) as needed. It is index of UVB prevention effect, and SPF is usually shown with number to 50 (there is indication indicating 50 or more called 50+, too), and prevention of UVB effect is high so that number is high. World Health Organization (WHO) and CDC (American Center for Disease Control and Prevention) recommend 15 or more. PA classification is index of UVA prevention effect, and there are +, ++, +++, four phases of ++++, and prevention of UVA effect is high so that there is much +. By labor, play, exercise the outdoors, let's repaint sunscreen every two hours. After sweaty time and swimming, let's repaint sunscreen. When we wipe off water and sweat which skin had with towel even if it is waterproof sunscreen, it may be wiped off together. After having wiped off water and sweat which skin had with towel, let's repaint sunscreen immediately.
    In addition, sunscreen includes ultraviolet ray inhibitor as ingredient. Ultraviolet ray inhibitor has ultraviolet scattering agent (inorganic system material) and ultraviolet ray absorbent (organic material). Ultraviolet scattering agent looks white at the time of application in comparison with ultraviolet ray absorbent with fine particles such as zinc oxide or titanium oxide, and there is little stimulation to skin. Ultraviolet ray absorbent does not look white at the time of application in comparison with ultraviolet scattering agent with methoxyKay arsenic acid octyl, dimethyl PABA octyl, octocrilene, but people who rarely get a rash are.
  7. Let's avoid ultraviolet ray from apparatuses for artificial sunlight and sunburn.
    Let's avoid ultraviolet ray from outbreak apparatus of man-made ultraviolet ray.
  8. Let's use ultraviolet ray forecast.
    The Meteorological Agency starts ultraviolet ray forecast in 2005 in Japan. At the Meteorological Agency, we use UV index for index of strength of ultraviolet ray. UV index is world common index. In "- for ultraviolet ray environmental health manual -2015 age" (Ministry of the Environment), measures such as lower table are introduced by number of UV index.
Ultraviolet ray measures depending on strength (UV index) of ultraviolet ray
UV indexStrength of ultraviolet rayUltraviolet ray measures
1-2Weak (Low)We can spend time outdoors in peace.
3-5Intermediate (Moderate)Let's use the shade as much as possible in the daytime.
Let's use long-sleeved shirt, sunscreen, hat as possible.
6-7Strong (High)
8-10It is very strong (Very High)Let's refrain from Japanese-Chinese going out as much as possible.
Let's use long-sleeved shirt, sunscreen, hat by all means.
11 or moreExtremely strong (Extreme)

Ultraviolet ray information in Yokohama-shi, the whole country

About UV index which is index of strength of ultraviolet ray, we can obtain information of predicted value and preliminary figure in Yokohama-shi and each places of the whole country from the Internet.

(supplement) let's be careful about lack of vitamin D

Vitamin D is included a lot in fish and mushrooms for food. On the other hand, there is structure which makes vitamin D in own body by taking ultraviolet ray in Nikko to skin to people. Vitamin D is under the skin, and materials are produced with material called 7 dehydrocholesterol which there is in the body abundantly by skin when they take UVB. In other words, people get necessary vitamin D using both vitamin D from meal and vitamin D by ultraviolet ray in Nikko. It is said that person of, a lot of depends on ultraviolet ray in Nikko for half or more of necessary vitamin D (400-1000 unit a day, 10-25 μg). Dark Asia of color of skin and African people are easy to fall into vitamin D deficiency disease in comparison with thin Westerners of color of skin. Person who is rarely exposed to sunlight in particular is easy to fall into vitamin D deficiency. In addition, attention is necessary for vitamin D production under the skin of falling into 5% or less when wavelength of ultraviolet ray making vitamin D is about the same as wavelength of discolored ultraviolet ray and is doing sunscreen of SPF30. In late years infants having a medical examination for high bowlegs and convulsions in outpatient department increase because of vitamin D deficiency in Japan. Calcium is lacking in and falls into without being absorbed enough when vitamin D is short even if we consume calcium by meal. We begin to dissolve calcium from bone and come to supply to have big symptoms such as convulsions when calcium concentration in blood decreases. As a result, strength of bone decreases and becomes easy to turn, and rickets (mainly child of period of growth) and symptom such as osteomalacia (adult) come to be caused.
About infants of vitamin D deficiency increasing, we influence that young women avoiding sunburn increased. Pregnant woman is in vitamin D lack state by avoiding sunburn, and therefore originally there are many few babies of bone mass, and it is thought that the removal food for perfection breast-feeding and atopic dermatitis, lack of sunbathing after life are piled up as risk factor.
Short sunbathing is necessary from the viewpoint of prevention of vitamin D deficiency. However, it is regarded as one method that we take in supplement of vitamin D when intake or sunbathing from food of vitamin D are difficult (references 5).

References ...

  1. United States Environmental Protection Agency(EPA), The Burning Facts. ; May 2001, p.1-6.
  2. United States Environmental Protection Agency(EPA), The Sun, UV, and You. A Guide to Sunwise Behavior. ; June 1999, p.1-13.
  3. AMERICAN ACADEMY OF PEDIATRICS, Committee on Environmental Health. ; Ultraviolet Light: A Hazard to Children. ; PEDIATRICS Vol. 104 No. 2 August 1999, p.328-333.
  4. Ministry of Health, Labour and Welfare cancer Grant in Aid "study on improvement in precision and inflection of local cancer registration" (chief researcher Hideaki Tsukuma) 2002 report.
  5. "- for ultraviolet ray environmental health manual -2015 age" March, 2015 revised edition, Ministry of the Environment environment Health Department environment security section. (the outside site)
  6. Office of Air and Radiation, United States Environmental Protection Agency(EPA), Prevent eye damage. Protect yourself from UV radiation. ; December 2004, p.1-2.
  7. Office of Air and Radiation, United States Environmental Protection Agency(EPA), A GUIDE TO THE UV INDEX. ; May 2004, p.1-8.
  9. WHO, Sunbeds, tanning and UV exposure. : Fact Sheet No 287. ; March 2005.
  10. Veierod MB, Weiderpass E, Thorn M, et al. A prospective study of pigmentation, sun exposure, and risk of cutaneous malignant melanoma in women. Journal of National Cancer Institute, Vol. 95, No. 20, October 15, 2003:p.1530-1538.
  11. Global Solar UV Index: A Practical Guide. A joint recommendation of the World Health Organization, World Meteorological Organization, United Nations Environment Programme, and the International Commission on Non-Ionizing Radiation Protection, World Health Organization, Geneva, Switzerland, 2002.
  12. WHO, Global disease burden from solar ultraviolet radiation. : Fact Sheet No 305. ; July 2006.
  13. Robyn Lucas, Tony McMichael, Wayne Smith, and Bruce Armstrong: Editors, Annette Pruss-Ustun, Hajo Zeeb, Colin Mathers, and Michael Repacholi, Solar ultraviolet radiation: global burden of disease from solar ultraviolet radiation (Environmental burden of disease series, no. 13.), Public Health and the Environment, World Health Organization, Geneva, Switzerland, 2006.
  14. Safe Work Australia (the outside site) (Australia government office concerned with labor security hygiene established in 2009), Guide on exposure to solar ultraviolet radiation (UVR) (the outside site); 12/AUGUST/2013.

May 18, 2004 publication
August 4, 2006 revision is supplementary
August 30, 2007 revision is supplementary
May 7, 2008 revision is supplementary
June 1, 2009 revision is supplementary
August 5, 2011 revision is supplementary
July 9, 2015 revision is supplementary
October 7, 2015 revision is supplementary

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