When rays reach the Earth, they change their property at the Earth's atmosphere, and are partly absorbed by ozone, small droplets of steam and air components such as oxygen, nitrogen, or carbon dioxide. The light includes three ranges of waves: infrared, visible, and ultraviolet. Infrared and ultraviolet rays cannot be seen with the unaided eye. Waves that have more energy than violet light are called ultraviolet rays. Ultraviolet (UV) radiation belongs to the optical range of electromagnetic waves and is between heat and ionizing (X-ray) radiation. Thus, ultraviolet has the properties of both heat and ionizing radiation. “Ultraviolet (UV) radiation that reaches the Earth’s surface is in wavelengths between 290 and 400 nm (nanometers, or billionths of a meter)” (Allen, 2001, n.p.). In accordance with the way of a generation, ultraviolet is like heat radiation range and, in accordance with biological effects, like ionizing radiation. Despite the similarity of the biological effect on the human body, the negative influence of UV exposure is much smaller than that of ionizing. This is due to a greater length of its waves, and thus lower energy quantum of UV rays. This paper is going to discuss the use of ultraviolet and how it works, the negative impact of ultraviolet and precautions against it.
The Use of Ultraviolet
Although the proportion of the total UV radiation is negligible, it plays an important role in human life. According to the biological activity, its range is divided into three sections: section A – wavelength from 400 to 315 nm; section B – wavelength from 315 to 280 nm; section C – wavelength from 280 to 10 nm. The Earth's surface, generally, obtains the radiation with a wavelength of 400 to 290 nm. Characteristic of this type of radiation is strong photochemical action. Penetrating into the skin to a depth of just 0.2 to 2 mm, it causes changes in cellular proteins and nucleic acids. As a result of the transfer of photon energy, charged atoms and molecules –ions and free radicals are generated, which take an active part in photo-biological processes of the body. Due to the formation of biologically active substances such as histamine, acetylcholine, etc., the activity of some enzymes (histaminase, tyrosine) and function of organs and tissues change. There is a general stimulatory effect of ultraviolet radiation, which is manifested in increased cell growth and tissue repair that in its turn accelerates wound healing of various origins including postsurgical.
“Skin exposed to UVB and UVA is more resistant to primary irritants, which may indicate the improvement of skin barrier functions” (Juzeniene, 2012, p. 112). The lack of ultraviolet radiation leads to a decrease in the body of vitamin D, which is synthesized under the influence of radiation in human skin. Calciferol activates the phosphorus-calcium metabolism, normalizes the processes of bone mineralization and is actively involved in other processes (regulation of excitability of the nervous system, the assimilation of proteins and minerals from food, etc.). The lack or absence of vitamin D in the body leads to pathological changes – violation of blood clotting, muscle weakness, osteoporosis, the complication of which is brittle bones due to leaching of calcium from them.
Ultraviolet radiation is widely used in sterilization and disinfection. It is one of the most common methods of disinfection of drinking water today. “UV can effectively ‘kill’ (deactivate or destroy) microorganisms such as viruses and bacteria, for example, when hanging cloth nappies, underwear and tea-towels outside on the clothesline” (Science Learning, 2008, n.p.).
Energy of UV underlies ultraviolet sterilizers' work, destroys microbiological contamination (for instance, E. coli, cholera, typhus pathogens, hepatitis viruses, salmonella, Giardia lamblia cysts and cryptosporidium). To that end, it is used ultraviolet radiation that has a wavelength of 260 nm or close to that. It passes through cell walls of microorganisms in the water and is absorbed by DNA, resulting in cessation of reproduction of microorganisms. This is the essence of the non-chemical method of disinfection.
A UV sterilizer is a cylindrical chamber that contains a UV lamp enclosed in a quartz tube, over which water flows. Lamps are mounted with special clamps. The principle of the sterilization system is as follows. First, the water enters through the bottom port of the reaction chamber of the UV sterilizer and flows around a mercury lamp, protected by a quartz tube. The radiation destroys the DNA molecule in bacterial cells and microorganisms, preventing their reproduction. The sterilized and ready to use water comes from the upper port.
Ultraviolet is also used in food industry. Ultraviolet radiation is one of the promising ways to reduce the number of microorganisms in cold store and in meat. UV rays have bactericidal and fungicidal properties. However, their use is not without difficulties: there is a need in specialized equipment and power source, and meat turns black on the side that is facing the UV light.
The death of microorganisms depends on the time of exposure to ultraviolet rays. The longer ultraviolet rays are the faster microbes die. A lethal dose can be achieved by a single long exposure or repeated equal in duration exposures, as the effect of UV rays is cumulative. Ultraviolet radiation, combined with low temperatures, has the most positive effect. In this case, unfavorable for microbial growth temperature conditions make them more favorable to destructive actions of ultraviolet rays. The following conditions are recommended for processing meat with UV rays: temperature 2 – 8 ° C, relative humidity 85 – 95%, continuous circulation of air at a speed of 2 m / min.
The development of the UV radiator is based on ultraviolet germicidal properties. That is the start of the use of ultraviolet in medicine. UV rays are used in therapy, laser biomedicine, disinfection, and in many other areas of health care. Modern characteristics of the ultraviolet lamp include the following parameters: the radiation power, the composition of spectrum, the type of glass, and the term of exploitation.
Medicine is one of the areas where ultraviolet light is used the most. Antibacterial treatment with germicidal lamps is carried out in all departments of hospitals, especially in surgical, operating, and infectious. UV properties to kill bacteria and viruses are used in clinics, health centers, as well as in industrial enterprises with different types of air pollution. They are also applied in preschools, which contributes to better combat with seasonal illnesses such as acute respiratory infections.
Germicidal UV lamps are divided into open and closed types. Open UV lamps are used for processing of premises by direct exposure to UV rays. This method requires absence of people in the room during the process. The germicidal lamp is turned on for a certain period of time after which the room has to be ventilated. Closed UV lamps are used for processing of space in the presence of people. Such lamps use special glass, which does not accumulate the ozone in the room.
Ultraviolet light is used in medicine to restore the human immune system, to treat various kinds of diseases, and in physiotherapy. With the help of ultraviolet light the treatment of joints, dermatological, and allergic diseases can be carried out.
There are a large number of UV lamps for domestic use. Some patients, who suffer from tubercular, cannot always be on a long-term inpatient treatment, so they spend many months at home. Their rooms and the entire apartments must be decontaminated in various ways, including ultraviolet radiation. Quartz UV lamps are suitable not only for chronic patients but also for prevention of various viral infections in homes with small children.
The Dangers of Ultraviolet
Prolonged and intense ultraviolet radiation could have an adverse effect on the body and cause pathological changes. At first, under the influence of ultraviolet light occurs formation of wrinkles. In fact, a nice tan has a short-term effect, so it is worth considering how much people pay for such beauty. In the body, each person has melanin, which is produced under exposure to sunlight, so in order to gain a tan, a person needs to trigger the chemical reaction. However, in addition to beautiful skin color, the person gets damaged vessels and heart strain, which can lead to deterioration of the cardiovascular system. Ultraviolet rays degrade collagen, which is responsible for skin elasticity, so the wrinkles occur. Women who spend little time in the sun, even in summer, stay young and attractive for longer period. If one does not want to lose skin elasticity, he/she has to be sure to reconsider his/her views on sunbathing.
Prolonged sun exposure t can cause burns from ultraviolet radiation. All people have a different reaction to the sun: some people practically do not burn even after prolonged sunbathing, others feel itching and redness on their skin even after a couple of minutes. “Sunburn (or erythema) is redness of the skin, which is due to increased blood flow in the skin caused by dilatation of the superficial blood vessels in the dermis as a result of exposure to UV radiation” (Exposure to Environmental Hazards, n.p.). In fact, people should be able to sunbathe, because it affects their health. If they do not use sunscreen, do not give their skin time to adjust, they can get severe burns that require a long-term treatment. In order not to burn, it is important to gradually increase the time spent in the sun, starting with 20 minutes a day. It is better to lie under an umbrella; it is safer.
Ultraviolet radiation can cause brown spots on the skin. Almost all women with age have dark spots caused by ultraviolet rays. Human skin has the ability to accumulate melanin, which is produced upon the effect of the sun. Thus, small brown spots like freckles occur. Such a "decoration" as dark spots does not make people more attractive, but rather causes resentment among others. Brown spots add years and cause uneven skin color.
Ultraviolet increases the tendency to skin cancer. Any expert in the field of medicine will confirm that prolonged exposure to sun rays is harmful for people’s health. It increases the risk of cancer, so it is necessary to be more careful. The skin has to be always covered with a protective layer of cream with SPF filters, to reduce the risk of cancer. Often, as a result of regular tanning, appear small birthmarks that in medicine are considered to be benign tumors.
Visual analyzer the mostly suffers from UV radiation. Sharp eye damage under UV radiation is called electric ophthalmia. This disease is manifested in outside body sensation or sand in the eyes, photophobia, lacrimation, and others. Chronic diseases include: conjunctivitis, cataract of lens. In production conditions, the most important are professional body lesions – photosensitivity (increased body sensitivity to light), solar ultraviolet radiation spectrum. They occur in severe forms of conjunctivitis, dermatitis, and general phenomena.
Precautions to Ultraviolet
In order to prevent negative influence of ultraviolet, it is necessary to rationally organize work and rest, find a proper location of a job and distance from powerful industrial sources of UV radiation. Protection from intense ultraviolet radiation can be achieved with: a reasonable work place, proper distance from a source of UV radiation, shielding from sources of radiation, shielding jobs, personal protection. According to Ultraviolet Radiation (n.d.):
Having equipment located in a separate room, alcove or low traffic area of a lab is ideal. To avoid exposure to other employees, avoid placing equipment in the direct vicinity of desk areas and or other equipment. The use of shields, curtains, UVR absorbing glass, or plastic is recommended. (n.p.)
The most rational method of protection is screening (shelter) of the sources of UV radiation. To that end, opaque metal sheets or filters are usually used. Personal protection includes: working clothing (suits, jackets, and white overalls), means for the protection of hands (gloves), face (protection shields), and eyes (glasses with filters).
Efficient and safe use of UV radiation, including in tanning salons, can only be achieved in strict accordance with contraindications to its use, individual characteristics of a patient (client): the state of the skin, presence of comorbidities, continuous medication, and others. Before visiting solariums with UV radiation for curative purposes, the client should consult a physician, physical therapist, dermatologist, venereologist, and an oncologist in order to assess his/her condition and get a prescription of radiation dose, provided there are no possible contraindications.
Analyzing all the information discussed above, it becomes clear that ultraviolet has both positive and negative impacts on people’s health and environment. In today's world, ultraviolet radiation is the most widely used in various fields: medicine, processes of sterilization, disinfection, cosmetics, food industry, etc. The ability of UV rays to kill various bacteria (bactericidal action) is of great practical importance. Extensive biological effects of UV rays make it possible to use specific doses for prophylactic and therapeutic purposes. Currently, ultraviolet radiation is widely used, especially for the prevention of various diseases. To that end, ultraviolet radiation is used to recover human environment and change its reactivity (in the first place - to enhance its immune biological properties). Unfortunately, prolonged and intense exposure to ultraviolet radiation could have an adverse effect on the body and cause pathological changes. Only following the simple rules and pieces of advice mentioned above will safe people’s health from negative effects of ultraviolet radiation.