What are the variables in ultraviolet radiation treatment? Time, distance, temperature, wavelength, intensity of the bug or bug. Many of the microorganisms found on environmental surfaces are pigmented. Of what possible advantage is the pigment? The pigment protects the bug from UV damage.
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What are the principles of ultraviolet (UV) radiation?
We review the principles of ultraviolet (UV) irradiation, the inactivation of infectious agents by UV, and current applications for the control of microorganisms. In particular, wavelengths between 200 and 280 nm (germicidal UV) affect the double-bond stability of adjacent carbon atoms in molecules …
What are the 3 types of UV radiation?
What are the different types of UV radiation? The most common form of UV radiation is sunlight, which produces three main types of UV rays: UVA. UVB. UVC. UVA rays have the longest wavelengths, followed by UVB, and UVC rays which have the shortest wavelengths.
What is the TLV of UV radiation?
The most hazardous UV radiation has wavelengths between 240 nm and 300 nm. In this wavelength range, the TLV is less than 10 mJ/cm 2, with the minimum TLV (the most hazardous radiation) being 270 nm (TLV = 3 mJ/cm 2)
What is the ultraviolet spectrum?
Last Updated on June 26, 2018 by opsweb1. Ultraviolet (UV) radiation occupies the portion of electromagnetic spectrum from 100 to 400 nanometers (nm). The UV spectrum consists of three regions, as designated by the Commission Internationale de l’Eclairage:
What are the factors of UV radiation?
Seven factors affecting solar UV radiationSolar elevation. Where the sun sits in the sky determines the level of UV radiation reaching us. ... Ozone. ... Cloud cover. ... Ground surface reflectivity. ... Altitude. ... Aerosols and pollutants. ... Direct and diffuse UV.
What are the three common properties of ultraviolet radiation?
Three properties of ultraviolet radiations similar to the visible light:They travel in straight lines as light does, with a speed equal to 3 x 108 m/s in vacuum.They obey laws of reflection and refraction.They are unaffected by electric and magnetic fields.
What are the components of ultraviolet rays?
Just as visible light consists of different colours that become apparent in a rainbow, the UV radiation spectrum is divided into three regions called UVA, UVB and UVC. As sunlight passes through the atmosphere, all UVC and most UVB is absorbed by ozone, water vapour, oxygen and carbon dioxide.
What are the 3 kinds of ultraviolet radiation and define each?
UVA rays have the longest wavelengths, followed by UVB, and UVC rays which have the shortest wavelengths. While UVA and UVB rays are transmitted through the atmosphere, all UVC and some UVB rays are absorbed by the Earth's ozone layer.
What is the frequency of ultraviolet radiation?
Ultraviolet radiation oscillates at rates between about 800 terahertz (THz or 1012 hertz) and 30,000 THz. When we talk about visible light, we refer to the different wavelengths of light across the visible spectrum by the names of colors.
Is ultraviolet high or low frequency?
UV has a higher frequency and shorter wavelength than visible light, and it has a lower frequency and longer wavelength than X-radiation. UV with its longer wavelength and less energy is less penetrating than X-ray and is sometimes absorbed by matter.
How is UV measured?
The best way to measure UV radiation it to use a spectroradiometer which permit to assess the energy amount of the UV radiation for each wavelenght. Having the spectrum of the radiation, you can easily evaluate the different component: UV-C (<280 nm), UV-B (280-320 nm) and UV-A (320-400 nm).
How does UV radiation work?
UV radiation has enough energy to break chemical bonds. Due to their higher energies, UV photons can cause ionization, a process in which electrons break away from atoms. The resulting vacancy affects the chemical properties of the atoms and causes them to form or break chemical bonds that they otherwise would not.
What are the effects of ultraviolet radiation on human health?
Exposure to UV rays can cause premature aging of the skin and signs of sun damage such as wrinkles, leathery skin, liver spots, actinic keratosis, and solar elastosis. UV rays can also cause eye problems. They can cause the cornea (on the front of the eye) to become inflamed or burned.
What are 3 uses of ultraviolet?
UV radiation is widely used in industrial processes and in medical and dental practices for a variety of purposes, such as killing bacteria, creating fluorescent effects, curing inks and resins, phototherapy and suntanning.
What is UVB and UVA?
Two types of UV light are proven to contribute to the risk for skin cancer: Ultraviolet A (UVA) has a longer wavelength, and is associated with skin aging. Ultraviolet B (UVB) has a shorter wavelength and is associated with skin burning.
What is UVA and UVB protection?
Broad-spectrum sun protection product helps protect your skin against both UVA and UVB rays. Sunscreen should be applied 15 minutes before exposing your skin to the sun – and reapplied at least every two hours. Physical, or mineral-based, UV ingredients like zinc oxide and titanium dioxide reflects UV rays.
What is the wavelength of ultraviolet radiation?
Ultraviolet (UV) radiation occupies the portion of electromagnetic spectrum from 100 to 400 nanometers (nm). The UV spectrum consists of three regions, as designated by the Commission Internationale de l’Eclairage: UV-A (315–400 nm) UV-B (280–315 nm) UV-C (100–280 nm)
What is UV radiation used for?
UV radiation is used in a wide variety of medical and industrial processes for killing bacteria or producing fluorescence; these include photocuring of inks and plastics (UV-A and UV-B), photoresist processes (all UV), solar simulation (all UV), cosmetic tanning (UV-A and UV-B), and dentistry (UV-A).
What are the effects of UV radiation on the eyes?
The eyes are very sensitive to UV radiation. Prolonged direct exposure to UV-B and UV-C light can cause serious effects such as conjunctivitis and photokeratitis.
How much radiation is dangerous above 240 nm?
Between 180 nm and 240 nm, the radiation becomes increasingly more hazardous to up to 10 mJ/cm 2 at 240 nm.
What is the wavelength of UV-A?
UV-A (315–400 nm) UV-B (280–315 nm) UV-C (100–280 nm) For most people, the main source of UV exposure is the sun. Exposure from the sun is typically limited to the UV-A region, since the earth’s atmosphere protects us from the more harmful UV‑C and UV-B regions.
Why is UV light useful?
Because of its ability to cause chemical reactions and excite fluorescence in materials , UV light has a large number of useful applications in modern society. Listed below are some of the uses of specific wavelength bands in the UV spectrum:
How long does it take for a UV ray to show up in your eyes?
The severity of these conditions depends on the duration, intensity, and wavelength. Symptoms may appear 6 to 12 hours after exposure and may subside after 24 to 36 hours with no permanent damage. Unlike the skin, the eyes do not develop a tolerance to repeated exposure to UV.
How does UV radiation affect the immune system?
UV irradiation from sunlight suppresses the immune system, which facilitates skin carcinogenesis by reducing cell-mediated immune responses that normally destroy developing skin tumors [44–46]. Exposure to UV results in a substantial reduction in numbers of Langerhans cells, as well as reducing the antigen-presenting ability of those remaining [47–49]. UVR also increases the release of immunosuppressive cytokines such as interleukin-10 from keratinocytes, and possibly from mast cells [50], increases pro-inflammatory cytokines such as IL-6 [51] and suppresses the release of immune-stimulating cytokines such as IL-12 [52]. A major contributor to UV-induced immunosuppression is DNA damage (reviewed in [22] ). UV exposure suppresses both contact hypersensitivity reactions and delayed-type hypersensitivity reactions to viral, bacterial, and fungal antigens and causes both local and systemic immune suppression (reviewed in [53] ).
How does UV irradiation affect collagen?
6 UV irradiation also enhances collagenase activity and contributes to wrinkle formation through collagen degradation in the dermal extracellular matrix (ECM). 6 UVB irradiation induces ROS production, which promotes downstream signal transduction in the dermis, causing skin damage and photoaging ( Figure 58.2 ).
What is UV light used for?
UV irradiation has been used for the control of pathogenic microorganisms in a variety of applications, such as control of legionellosis, as well as disinfection of air, surfaces, and instruments. 278,279 At certain wavelengths, UV light will break the molecular bonds in DNA, thereby destroying the organism.
What is the role of TGF-1 in dermal strength?
TGF-β1 is essential for dermal strength and is partially responsible for the contraction of the dermis. TGF-β1 activates the production of collagen, fibronectin, glycosaminoglycans, and elastin by fibroblasts and is the most powerful known stimulator of collagen synthesis. 10.
What temperature is needed for thermal inactivation?
Above 55° C (131° F), thermal inactivation is of primary importance. Use of a simple reflector or solar cooker can achieve temperatures of 65° C (149° F), which will pasteurize the water (see section on Heat disinfection ).
What temperature is needed for solar disinfection?
UV and thermal inactivation are synergistic for solar disinfection of drinking water in transparent plastic bottles. Above 55° C (131° F), thermal inactivation is of primary importance.
Is UV irradiation a biocide?
Ultraviolet (UV) irradiation has been used successfully as a biocide for a broad spectrum of planktonic bacteria in water processing, food and air disinfection and has been used for Legionella eradication. 141,142 However, the intensity of UV irradiation and the amount of time that the micro-organ i sms are exposed to radiation has a bearing on efficacy.
What is UV radiation used for?
Ultraviolet (UV) radiation is widely used to sterilize water for beverages and food products, for secondary treatment of waste-water, and to disinfect drinking water at the community and household level. It has not been well adapted to field use because of the requirements for power. In sufficient doses of energy, all water-borne enteric pathogens are inactivated by UV radiation. The ultraviolet waves must actually strike the organism, so the water must be free of particles that would act as a shield. The UV rays do not alter the water, but they also do not provide any residual disinfecting power. Recently a portable, battery operated unit was marketed for small quantity disinfection (Hydro-Photon Inc, Blue Hill, ME). Although previous data suggested limited ability of monochromatic UV rays to inactivate protozoan cysts, company product testing appears solid and shows effectiveness against important water-borne pathogens, including Cryptosporidia. Simple, table-size UV units with low power requirements are available for international applications (WaterHealth, Lake Forest, CA).
How does UV radiation affect skin?
UV radiation disrupts skin homeostasis in part by causing a loss of retinoid receptors. Retinoid receptors participate in epidermal growth and differentiation. Animal studies point to an inhibitory role of beta-carotene in UV-induced skin cancer.
How to reduce risk of melanoma?
Sunlight and UVR exposure is the only modifiable risk factor for melanoma. Protection from UVR is the primary strategy to decrease melanoma risk; optimal use of sun protection and limiting sun exposure can mitigate one's risk for skin cancer, regardless of the age of implementation. Standard recommendations to decrease UVR exposure include avoidance of the sun during the peak hours of 10 a.m. to 4 p.m., seeking shade whenever possible, covering the skin surface with sun-protective clothing including wide-brimmed hats, long-sleeved shirts, long pants, and sunglasses, and using broad-spectrum sunscreen with a sun protective factor (SPF) of 15 or greater to cover exposed skin surfaces. Regular application of SPF 15+ sunscreen in adults has been demonstrated to decrease melanoma risk in a randomized trial. 20 Appropriate type, timing, frequency, and amount of sunscreen applied are important factors in effective primary prevention. The FDA has legislated regulations for over-the-counter sunscreens. Highlights of these regulations include the following: Sunscreen products that protect against both UVA and UVB radiation will be labeled “Broad Spectrum” and “SPF 15” (or higher) on the front label; sunscreen products that are not broad spectrum or that are broad spectrum with SPF values from 2 to 14 will be labeled with a warning; and the front label must limit water resistance claims to either 40 minutes or 80 minutes, based on standard testing to determine the length of time for which a user can expect to get the declared SPF level of protection while swimming or sweating. Sun protective clothing guards the skin from UVR more effectively than sunscreen. Barriers to the implementation of sun protection behaviors include discomfort from sun protective clothing, inconvenience of applying sunscreen, and denial of personal risk for skin cancer. Furthermore, studies have indicated that tanning may be an addictive behavior. Based on the growing use of tanning beds by teenagers and the growing evidence that tanning bed use increases the risk of melanoma, in 2014 the FDA required that indoor tanning devices be labeled with a visible, black box warning stating that they should not be used by people younger than 18. The FDA has also proposed that a rule to protect youth from the risks of these devices by restricting use to only adults aged 18 or older. To date, 14 states have passed legislation that bans indoor tanning for those younger than 18.
How does UVB damage DNA?
UVB directly damages DNA through the formation of DNA “photoproducts” or dimers formed by the covalent bonding of two adjacent pyrimidine bases as a result of the absorption of UVR photons. 143 A few different types of dimers can form, but the one most frequently induced by UVB is the cyclobutane pyrimidine dimer (CPD).
What is the mechanism linking UV radiation to skin cancer?
Proposed Mechanism Linking Ultraviolet Radiation to Skin Cancer. UVR from the sun consists of three different ultraviolet (UV) wavelengths— UVA (315–400 nm), UVB (280–315 nm) and UVC (100–280 nm). UVC rays do not reach the Earth's surface owing to stratospheric ozone and so are not considered a source of UVR damage to the skin.
What is the UVB portion of the solar spectrum?
Animal studies confirm the carcinogenic effects of UV radiation and indicate that the ultraviolet B (UVB) portion (280 to 320 nm) of the solar spectrum is primarily responsible for the carcinogenic properties of sunlight.
Does skin cancer have photodamage?
Increased levels of DNA photodamage are detected in the normal epidermis of individuals after exposure to solar UV radiation, and analysis of mutational spectra in human nonmelanoma skin cancer DNA shows that mutations specific for UV radiation (dipyrimidine mutations) often are present.
How many spectral areas does UV have?
UV radiation is divided into four distinct spectral areas including vacuum UV (100–200 nm), UVC (200–280 nm), UVB (280–315 nm) and UVA (315–400 nm). Only part of UVB and UVA can reach on earth, because wavelengths shorter than 280 nm are filtered out by the atmosphere especially by the “ozone layer”.
What is the difference between irradiation with lower dose and higher dose?
Irradiation with lower dose (75.5 J/ m2) allowed the maintenance of the physiological homeostasis. While higher dose (755 and 2265 J/m2) delivered to neutrophils led to potential damage, by increasing the concentration of NO metabolites.
Does UV light kill bacteria?
No resistance of microorganisms to UV irradiation has been reported, and multi- antibiotic resistant strains are as susceptible as their wild-type counterparts. Low and mild doses of UV kill microorganisms by damaging the DNA, while any DNA damage in host cells can be rapidly repaired by DNA repair enzymes.
Does UBI affect phagocytic cells?
UBI may enhance the phagocytic capacity of various phagocytic cells (neutrophils and dendritic cells), inhibit lymphocytes, and oxidize blood lipids. The oxidative nature of UBI may have mechanisms in common with ozone therapy and other oxygen therapies.
Why is UV treatment of water so common?
UV treatment of water (potable and wastewater) is increasingly common because the process is effective against a wide range of microorganisms, overdose is not possible, chemical residues or by-products are avoided, and water quality is unaffected.
What wavelengths affect the double bond stability of adjacent carbon atoms in molecules?
In particular, wavelengths between 200 and 280 nm (germicidal UV) affect the double-bond stability of adjacent carbon atoms in molecules including pyrimidines, purines and flavin. Thus, UV inactivation of microorganisms results from the formation of dimers in RNA (uracil and cytosine) and DNA (thymine and cytosine).
Applications
Health Effects
Common Sources of UV Radiation
Portable UV Sources
Other Hazards Associated with UV Light
- High pressure
Do not touch the lamp with bare skin. Skin oils on a hot lamp permanently etch the quartz (devitrification), causing local overheating. Strain buildup leads to premature, catastrophic failure. Wiping the lamp with alcohol before installation is a useful precaution. High-pressure lamps hav… - Ozone
Ozone is produced by the absorption of short-wavelength UV by oxygen. Ozone is a powerful oxidizing agent and can damage cells, especially in the lungs. Ensure that adequate ventilation is available when using intense sources of short-wavelength UV-B and UV-C.
UV Exposure Limits
Limiting UV Exposure
Engineering Controls
Administrative Controls
Personal Protective Equipment