· Sunlight consists of 2 types of light waves or radiation; visible and invisible. Visible light has a spectrum of 7 colors ranging from red to violet. Invisible ultraviolet (UV) radiation is not possible for detection to the human eye, e.g. infrared and X-rays. UV radiaition is further divided into 3 different types - UVC, UCB and UVA.
· The very toxic UVC is filtered out by the ozone layer. The ozone layer also filters UVB but about 1% of UVB still passes through to reach earth. UVB is what causes sunburn and even skin cancers after prolong exposure.
· UVA is abundant around us since the ozone layer poses no obstruction. UVA is what causes photoaging of the skin and is linked to photosensitivity resulting from certain diseases (e.g. lupus and the consumption of some drugs and herbs).
· Whether the weather is windy, cloudy or foggy during the day, harmful UV rays are still able to penetrate through.
1- UV light can damage the human skin.
2- UV light or phototherapy vitiligo treatment can help create repigmentation.
3- Possible eye damage can result from high doses of UV light, particularly to the cornea which is a good absorber of UV light.
4- High doses of UV light can cause a temporary clouding of the cornea; called 'snow-blindness' and chronic doses have been tentatively linked to the formation of cataracts.
5- A Pinguecula or a Pterygium both growths on the eye, may be caused by UV light exposure.
6- UV light can exert deleterious effects on melanin.
7- Many things that are invisible to the human eye become visible under UV light.
8- Sun tanning describes a darkening of the skin (especially of fair-skinned individuals) in a natural physiological response stimulated by exposure to ultraviolet radiation from sunshine (or a sunbed).
9- UVA rays are primarily absorbed within the lens of the human eye, though there are no documented disorders of the human eye from UVA.
10- A positive effect of UVB exposure is that it induces the production of vitamin D in the skin.
11- UVA, UVB and UVC can all damage collagen fibres and thereby accelerate aging of the skin.
12- Both UVA and UVB destroy vitamin A in skin which may cause further damage.
13- In general, UVA is the least harmful but can contribute to the aging of skin, DNA damage and possibly skin cancer. UVB rays are the ones that burn the skin and can damage the eyes.
14- There are also naturally occurring compounds found in rainforest plants that have been known to protect the skin from UV radiation damage, such as the fern Phlebodium Aureum.
15- New snow can reflect up to 80% of ultraviolet rays, according to the World Health Organization, while normal ground surfaces and bodies of water tend to reflect less than 10%.
16- Mountaineers are exposed to higher than ordinary levels of UV radiation, both because there is less atmospheric filtering and because of reflection from snow and ice.
17- Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than soft X-rays.
18- Ultraviolet is colloquially called black light, as it is invisible to the human eye.
19- UV light systems produce ultraviolet radiation falling into one to three UV bands: UVA, UVB and UVC.
20- Wavelengths of UV light in the range of 200 to 280 nm have been demonstrated to effectively inactivate bacteria and viruses due to DNA mutations induced by the absorption of UV light by DNA molecules.
21- Longwave UV light (315nm to 400nm), or UV-A, refers to what we commonly call 'black light'.
22- Germicidal UV light (200nm to 280nm), or UV-C, is effective in microbial control.
23- UVC rays are the highest energy, most dangerous type of ultraviolet light.
24- Scientists have divided the ultraviolet part of the spectrum into three regions: the near ultraviolet, the far ultraviolet, and the extreme ultraviolet.
25- The three regions are distinguished by how energetic the ultraviolet radiation is and by the 'wavelength' of the ultraviolet light, which is related to energy. The near ultraviolet, abbreviated NUV, is the light closest to optical or visible light. The extreme ultraviolet, abbreviated EUV, is the ultraviolet light closest to X-rays and is the most energetic of the three types. The far ultraviolet, abbreviated FUV, lies between the near and extreme ultraviolet regions.
26- Scientists have developed a UV index to help people protect themselves from these harmful ultraviolet waves.
27- UV light is also an essential tool in thin-layer chromatography (TLC), a process that chemists use to identify the components in a mixture.
28- Many polymers used in consumer products are degraded by UV light and need addition of UV stabilisers to inhibit attack.
29- Polymers exposed to UV light will oxidize thus raising the surface energy of the polymer.
30- Cystine, methionine and aromatic amino acids can be destroyed by UV light.
31- Ultraviolet levels are over 1,000 times higher at the equator than at the polar regions so it is presumed that marine life at the equator are much better adapted to the higher environmental UV light than organisms in the polar regions.
32- Apple juice or cider is treated with UV light to reduce the levels of microbial pathogens.
33- UV light can be used to pasteurise fruit juices by flowing the juice over a high intensity ultraviolet light source.
34- UV light has been proven for decades to effectively disinfect air, surfaces and water.
35- UV light can destroy many types of virus, mould and bacteria.
36- Ultraviolet radiation is used in several food processes to remove unwanted microorganisms.
37- Many fruits, flowers and seeds stand out more strongly from the background in ultraviolet wavelengths as compared to human colour vision.
38- Many birds have patterns in their plumage that are invisible at usual wavelengths but observable in ultraviolet and the urine and other secretions of some animals, including dogs, cats, and human beings, is much easier to spot with ultraviolet.
39- The urine of many species of rodent strongly reflects ultraviolet light.
40- Ultraviolet light is generated predominantly by hot, young massive stars.
41- The Sun emits ultraviolet radiation in the UVA, UVB, and UVC bands, but because of absorption in the atmosphere's ozone layer, 99% of the ultraviolet radiation that reaches the Earth's surface is UVA.
42- Humidity may increase the effects of UV light.
43- Ultraviolet Light Absorbers (UVAs) are molecules used in organic materials (polymers, paints, etc).
44- Ultraviolet traps are used to eliminate various small flying insects.
45- Ultraviolet lamps are used to sterilize workspaces and tools used in biology laboratories and medical facilities.
46- UV lights have been installed in some parts of the world in public toilets and on public transport, for the purpose of deterring substance abuse.
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