"However, it operates not by inducing direct DNA damage, but by producing reactive oxygen species which damage DNA indirectly. UVA (see above) induces a cosmetic tan but little extra melanin protection against sun damage, sun burn, or cancer. Ultraviolet B (UVB) radiation is in the wavelength range 280 to 320 nm. Much of this band is blocked by the Earth's ozone layer, but some penetrates. UVB: A person's natural skin color affects their reaction to exposure to the sun. An individual's natural skin color can vary from a dark brown to a nearly colorless pigmentation, which may appear white ."
"the Earth's natural stratospheric ozone layer that shields the biosphere against solar UV radiation; increased UV levels at the surface can cause skin cancer or even blindness. CFC-113 was one of the many CFCs that were produced to eliminate toxic and flammable substances in the areas that they were used. It has been used as a cooling agent in refrigerants and air conditioners, aerosol propellant, and a cleansing agent for electrical and electronic components. CFC-113 is one of the three most popular CFCs, along with CFC-11 and CFC-12 and saw much use in its time. CFC-113 is a refrigerant used"
"ozone layer due to the subsequent conversion of atmospheric into. The ozone layer blocks ultraviolet solar radiation, permitting life on land. Other atmospheric functions important to life include transporting water vapor, providing useful gases, causing small meteors to burn up before they strike the surface, and moderating temperature. This last phenomenon is known as the greenhouse effect: trace molecules within the atmosphere serve to capture thermal energy emitted from the ground, thereby raising the average temperature. Water vapor, carbon dioxide, methane, nitrous oxide, and ozone are the primary greenhouse gases in the atmosphere. Without this heat-retention effect, the average surface"
"substances (ODS). These compounds are transported into the stratosphere by the winds after being emitted from the surface. Once in the stratosphere, they release halogen atoms through photodissociation, which catalyze the breakdown of ozone (O) into oxygen (O). Both types of ozone depletion were observed to increase as emissions of halocarbons increased. Ozone depletion and the ozone hole have generated worldwide concern over increased cancer risks and other negative effects. The ozone layer prevents most harmful UVB wavelengths of ultraviolet light (UV light) from passing through the Earth's atmosphere. These wavelengths cause skin cancer, sunburn and cataracts, which were projected"
"An MAA known as palythine, derived from seaweed, has been found to protect human skin cells from UV radiation even in low concentrations. ""MAAs, in addition to their environmental benefits, appear to be multifunctional photoprotective compounds,"" says Dr. Karl Lawrence, lead author of a paper on the research. ""They work through the direct absorption of UVR [ultraviolet radiation] photons, much like the synthetic filters. They also act as potent antioxidants, which is an important property as exposure to solar radiation induces high levels of oxidative stress, and this is something not seen in synthetic filters."" Some MAAs protect cells from"
"28, 2003, which operated until early 2012. Ozone layer The Ozone layer or ozone shield is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet radiation. It contains high concentrations of ozone (O) in relation to other parts of the atmosphere, although still small in relation to other gases in the stratosphere. The ozone layer contains less than 10 parts per million of ozone, while the average ozone concentration in Earth's atmosphere as a whole is about 0.3 parts per million. The ozone layer is mainly found in the lower portion of the stratosphere, from approximately above"
"sunburn and other damage to the skin caused by ultraviolet light (see sunscreen). It is the broadest spectrum UVA and UVB absorber that is approved for use as a sunscreen by the U.S. Food and Drug Administration (FDA), and is completely photostable. When used as an ingredient in sunscreen, zinc oxide blocks both UVA (320–400 nm) and UVB (280–320 nm) rays of ultraviolet light. Zinc oxide and the other most common physical sunscreen, titanium dioxide, are considered to be nonirritating, nonallergenic, and non-comedogenic. Zinc from zinc oxide is, however, slightly absorbed into the skin. Many sunscreens use nanoparticles of zinc"
"Umbelliferone Umbelliferone, also known as 7-hydroxycoumarin, hydrangine, skimmetine, and ""beta""-umbelliferone, is a natural product of the coumarin family. It absorbs ultraviolet light strongly at several wavelengths. Despite several indications that this chemical is photomutagenic, it is used in sunscreens. Umbelliferone has been reported to have antioxidant properties. It is a yellowish-white crystalline solid that has a slight solubility in hot water, but high solubility in ethanol. Umbelliferone's name is from the umbelliferae family of plants, and the plant family in turn was named for their umbrella-shaped inflorescences, each called an umbel. Umbelliferone occurs in many familiar plants from the Apiaceae"
"instruments, provided by CERES, part of the NASA's Earth Observing System (EOS), are designed to measure both solar-reflected and Earth-emitted radiation. The major atmospheric gases (oxygen and nitrogen) are transparent to incoming sunlight but are also transparent to outgoing thermal (infrared) radiation. However, water vapor, carbon dioxide, methane and other trace gases are opaque to many wavelengths of thermal radiation. The Earth's surface radiates the net equivalent of 17 percent of the incoming solar energy in the form of thermal infrared. However, the amount that directly escapes to space is only about 12 percent of incoming solar energy. The remaining"
"Greenhouse gas A greenhouse gas is a gas that absorbs and emits radiant energy within the thermal infrared range. Greenhouse gases cause the greenhouse effect. The primary greenhouse gases in Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide and ozone. Without greenhouse gases, the average temperature of Earth's surface would be about , rather than the present average of . The atmospheres of Venus, Mars and Titan also contain greenhouse gases. Human activities since the beginning of the Industrial Revolution (around 1750) have produced a 40% increase in the atmospheric concentration of carbon dioxide (), from 280 ppm"
"nm) is screened out by nitrogen. UV radiation capable of penetrating nitrogen is divided into three categories, based on its wavelength; these are referred to as UV-A (400–315 nm), UV-B (315–280 nm), and UV-C (280–100 nm). UV-C, which is very harmful to all living things, is entirely screened out by a combination of dioxygen (< 200 nm) and ozone (> about 200 nm) by around altitude. UV-B radiation can be harmful to the skin and is the main cause of sunburn; excessive exposure can also cause cataracts, immune system suppression, and genetic damage, resulting in problems such as skin cancer."
"eventually reach the upper atmosphere. Once the refrigerant reaches the stratosphere, UV radiation from the Sun homolytically cleaves the chlorine-carbon bond, yielding a chlorine radical. These chlorine radicals catalyze the breakdown of ozone into diatomic oxygen, depleting the ozone layer that shields the Earth's surface from strong UV radiation. Each chlorine radical remains active as a catalyst until it binds with another radical, forming a stable molecule and quenching the chain reaction. Prior to 1994, most automotive air conditioning systems used R-12 as a refrigerant. It was replaced with R-134a refrigerant, which has no ozone depletion potential. Old R-12 systems"
"In cosmetic and skin care products, titanium dioxide is used as a pigment, sunscreen and a thickener. As a sunscreen, it is notable in that combined with zinc oxide, it is considered to be an effective sunscreen that is less harmful to coral reefs than sunscreens that include chemicals such as oxybenzone and octinoxate. Titanium dioxide is found in the majority of physical sunscreens because of its high refractive index, its strong UV light absorbing capabilities and its resistance to discolouration under ultraviolet light. This advantage enhances its stability and ability to protect the skin from ultraviolet light. Nano-scaled (particle"
"Sunscreen Sunscreen, also known as sunblock, sun cream or suntan lotion, is a lotion, spray, gel or other topical product that absorbs or reflects some of the sun's ultraviolet (UV) radiation and thus helps protect against sunburn. Diligent use of sunscreen can also slow or temporarily prevent the development of wrinkles, moles and sagging skin. Depending on the mode of action, sunscreens can be classified into physical sunscreens (i.e., those that reflect the sunlight) or chemical sunscreens (i.e., those that absorb the UV light). Medical organizations such as the American Cancer Society recommend the use of sunscreen because it aids"
"a shield for the biosphere against the mutagenic and other damaging effects of solar UV radiation (see ozone layer). Ozone is formed near the Earth's surface by the photochemical disintegration of nitrogen dioxide from the exhaust of automobiles. Ground-level ozone is an air pollutant that is especially harmful for senior citizens, children, and people with heart and lung conditions such as emphysema, bronchitis, and asthma. The immune system produces ozone as an antimicrobial (see below). Liquid and solid O have a deeper blue color than ordinary oxygen and they are unstable and explosive. Ozone is a pale blue gas condensable"
"Titanium dioxide nanoparticle Titanium dioxide nanoparticles, also called ultrafine titanium dioxide, are particles of titanium dioxide (TiO) with diameters less than 100 nm. Ultrafine TiO is used in sunscreens due to its ability to block UV radiation while remaining transparent on the skin, and its photocatalytic sterilizing properties also make it useful as an additive in construction materials, for example in antifogging coatings and self-cleaning windows. The health risks of ultrafine TiO from dermal exposure on intact skin are considered extremely low, and it is considered safer than other substances used for UV protection. However, in the context of TiO"
"the 113th United States Congress by Rep. Ed Whitfield (R, KY-1) and Sen. Jack Reed (D, RI), and signed into law by President Barack Obama on November 26, 2014. Sunscreen (also commonly known as ""sun screen"", ""sunblock"", ""suntan lotion"", ""sunburn cream"", ""sun cream"" or ""block out"") is a lotion, spray, gel or other topical product that absorbs or reflects some of the sun's ultraviolet (UV) radiation on the skin exposed to sunlight and thus helps protect against sunburn. Depending on the mode of action, sunscreens can be classified into physical sunscreens (i.e., those that reflect the sunlight) or chemical sunscreens"
"methoxycinnamate are photoprotective agents used in many sunscreens, providing broad-spectrum UV coverage, including UVB and short-wave UVA rays. Photoprotection Photoprotection is the biochemical process that helps organisms cope with molecular damage caused by sunlight. Plants and other oxygenic phototrophs have developed a suite of photoprotective mechanisms to prevent photoinhibition and oxidative stress caused by excess or fluctuating light conditions. Humans and other animals have also developed photoprotective mechanisms to avoid UV photodamage to the skin, prevent DNA damage, and minimize the downstream effects of oxidative stress. In organisms that perform oxygenic photosynthesis, excess light may lead to photoinhibition, or photoinactivation"
"Bisoctrizole Bisoctrizole (INN/USAN, marketed by BASF as Tinosorb M and by MPI as Milestab 360, INCI methylene bis-benzotriazolyl tetramethylbutylphenol) is a benzotriazole-based organic compound that is added to sunscreens to absorb UV rays. Bisoctrizole is a broad-spectrum ultraviolet radiation absorber, absorbing UVB as well as UVA rays. It also reflects and scatters UV. Bisoctrizole is a hybrid UV absorber, the only organic UV filter produced in microfine organic particles (< 200 nm), like microfine zinc oxide and titanium dioxide. Where other organic UV absorbers need to be dissolved in either the oil or water phase, bisoctrizole dissolves poorly in both."
"Bisoctrizole Bisoctrizole (INN/USAN, marketed by BASF as Tinosorb M and by MPI as Milestab 360, INCI methylene bis-benzotriazolyl tetramethylbutylphenol) is a benzotriazole-based organic compound that is added to sunscreens to absorb UV rays. Bisoctrizole is a broad-spectrum ultraviolet radiation absorber, absorbing UVB as well as UVA rays. It also reflects and scatters UV. Bisoctrizole is a hybrid UV absorber, the only organic UV filter produced in microfine organic particles (< 200 nm), like microfine zinc oxide and titanium dioxide. Where other organic UV absorbers need to be dissolved in either the oil or water phase, bisoctrizole dissolves poorly in both."
"for respiration; nitrogen is fixed by bacteria and lightning to produce ammonia used in the construction of nucleotides and amino acids; and carbon dioxide is used by plants, algae and cyanobacteria for photosynthesis. The atmosphere helps to protect living organisms from genetic damage by solar ultraviolet radiation, solar wind and cosmic rays. The current composition of the Earth's atmosphere is the product of billions of years of biochemical modification of the paleoatmosphere by living organisms. The term stellar atmosphere describes the outer region of a star and typically includes the portion above the opaque photosphere. Stars with sufficiently low temperatures"
"Homosalate Homosalate is an organic compound used in some sunscreens. It is an ester formed from salicylic acid and 3,3,5-trimethylcyclohexanol, a derivative of cyclohexanol. Contained in 45% of U.S. sunscreens, it is used as a chemical UV filter. The salicylic acid portion of the molecule absorbs ultraviolet rays with a wavelength from 295 nm to 315 nm, protecting the skin from sun damage. The hydrophobic cyclohexanol portion provides greasiness that prevents it from dissolving in water. Similar to other UV filter compounds, more homosalate is absorbed into the stratum corneum of the face (25% of applied dose) versus back of"
"the major greenhouse gases are water, carbon dioxide, methane, nitrous oxide, ozone, and CFCs. These gases can absorb infrared radiation from the Earth's surface as it passes through the atmosphere. The most important greenhouse gas is water vapor because it can trap about 80 percent of outgoing IR radiation. The second most important greenhouse gas, and the most important one affected by man-made sources into the atmosphere, is carbon dioxide. The reason for why greenhouse gases can absorb infrared radiation is their molecular structure. For example, carbon dioxide has two basic modes of vibration that create a strong dipole-moment, which"
"by encapsulating commercially used UV filters, while being not only adherent to the skin but also non-penetrant. This strategy inhibits primary UV-induced damage as well as secondary free radicals. Sunscreen Sunscreen, also known as sunblock, sun cream or suntan lotion, is a lotion, spray, gel or other topical product that absorbs or reflects some of the sun's ultraviolet (UV) radiation and thus helps protect against sunburn. Diligent use of sunscreen can also slow or temporarily prevent the development of wrinkles, moles and sagging skin. Depending on the mode of action, sunscreens can be classified into physical sunscreens (i.e., those that"
"the sunscreen controversy. Padimate A Padimate A is an organic compound that is an ingredient in some sunscreens. It is an ester derivative of PABA. This aromatic chemical absorbs ultraviolet rays thereby preventing sunburn. However, its chemical structure and behaviour is similar to an industrial free radical generator. In Europe this chemical was withdrawn in 1989 for unstated reasons. In the US it was never approved for use in sunscreens. The photobiological properties of padimate O and padimate A resemble that of Michler's ketone. These compounds have been shown to increase the lethal effects of UV-radiation on cells. This photochemistry"
"Ecamsule Ecamsule (USAN, trade name Mexoryl SX, INCI terephthalylidene dicamphor sulfonic acid) is an organic compound which is added to many sunscreens to filter out UVA rays. It is a benzylidene camphor derivative, many of which are known for their excellent photostability. Although there are a few different UV absorbers with the trade name Mexoryl, only two of them are widely used where approved. Mexoryl SX (water-soluble) and Mexoryl XL (INCI Drometrizole trisiloxane, oil-soluble). Together they show a synergistic effect in protection. The patents are held by L'Oréal. Sunscreens containing ecamsule are exclusive to L'Oréal and its brands. Exposed to"
"it passed in front of the Sun, and detected whether solar ultraviolet radiation was absorbed at certain wavelengths, which would indicate the presence of gas particles, and therefore an atmosphere. The airglow spectrometer detected extreme ultraviolet radiation emanating from atoms of gaseous hydrogen, helium, carbon, oxygen, neon, and argon. Unlike the occultation spectrometer, it did not require backlighting from the Sun, and could move along with the rotatable scan platform on the spacecraft. The experiment's most important goal was to ascertain whether Mercury had an atmosphere, but would also gather data at Earth and Venus and study the interstellar background"
"that the residual ozone molecules detach from oxygen molecules after the oxidation process. Thanks to this characteristic of ozone, there is no hazardous by-products produced afterwards. Ultraviolet(UV) is an electromagnetic radiation found in sunlight. UV disinfection is environmentally safe and recognized as highly effective on inactivating a wide range of pathogens, including viruses, bacteria and parasites. It is also known for its capability of successfully eliminating hazardous and environmentally unacceptable chemicals such as chlorine and other associated disinfection by-products. UV also covers a number of applications: drinking water, food and beverage, aquaculture, power generation, cooling water microelectronics, pharmaceutical, wastewater disinfection,"
"Avobenzone Avobenzone (trade names Parsol 1789, Milestab 1789, Eusolex 9020, Escalol 517, Neo Heliopan 357 and others, INCI Butyl Methoxydibenzoylmethane) is an oil-soluble ingredient used in sunscreen products to absorb the full spectrum of UVA rays. Avobenzone was patented in 1973 and was approved in the EU in 1978. It was approved by the FDA in 1988. Its use is approved worldwide. Pure avobenzone is a whitish to yellowish crystalline powder with a weak odor, dissolving in isopropanol, decyl oleate, capric acid/caprylic acid triglycerides and other oils. Avobenzone is a dibenzoylmethane derivative. Avobenzone exists in the ground state as a"
"radiation (chemical sunscreens) or opaque materials such as zinc oxide or titanium oxide to physically block UV radiation (physical sunscreens). Chemical and mineral sunscreens vary in the wavelengths of UV radiation blocked. Broad-spectrum sunscreens contain filters that protect against UVA radiation as well as UVB. Although UVA radiation does not primarily cause sunburn, it does contribute to skin aging and an increased risk of skin cancer. Sunscreen is effective and thus recommended for preventing melanoma and squamous cell carcinoma. There is little evidence that it is effective in preventing basal cell carcinoma. Typical use of sunscreen does not usually result"
"other gases such as hydrocarbons (including ethane, diacetylene, methylacetylene, cyanoacetylene, acetylene, propane), argon, carbon dioxide, carbon monoxide, cyanogen, hydrogen cyanide and helium. The hydrocarbons are thought to form in Titan's upper atmosphere in reactions resulting from the breakup of methane by the Sun's ultraviolet light, producing a thick orange smog. Titan has no magnetic field and sometimes orbits outside Saturn's magnetosphere, directly exposing it to the solar wind. This may ionize and carry away some molecules from the top of the atmosphere. Titan's atmosphere supports an opaque cloud layer that obscures Titan's surface features at visible wavelengths. The haze that"
"Padimate A Padimate A is an organic compound that is an ingredient in some sunscreens. It is an ester derivative of PABA. This aromatic chemical absorbs ultraviolet rays thereby preventing sunburn. However, its chemical structure and behaviour is similar to an industrial free radical generator. In Europe this chemical was withdrawn in 1989 for unstated reasons. In the US it was never approved for use in sunscreens. The photobiological properties of padimate O and padimate A resemble that of Michler's ketone. These compounds have been shown to increase the lethal effects of UV-radiation on cells. This photochemistry is relevant to"
"minerals, called carbonates. However, despite the use of many orbiting instruments that looked for carbonates, very few carbonate deposits have been found. Today, it is thought that much of the carbon dioxide in the Martian air was removed by the solar wind. Researchers have discovered a two-step process that sends the gas into space. Ultraviolet light from the Sun could strike a carbon dioxide molecule, breaking it into carbon monoxide and oxygen. A second photon of ultraviolet light could subsequently break the carbon monoxide into oxygen and carbon which would get enough energy to escape the planet. In this process"