The abundant formation of hydroxyl radicals in the atmosphere
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The hydroxyl radical (OH) is the primary cleansing agent of the lower atmosphere, providing the dominant sink for many greenhouse gases (e.g., CH4, hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons) and pollutants (e.g., CO, non-methane hydrocarbons). Steady-state lifetimes of these trace gases are determined by the morphology of their atmospheric distribution, the kinetics of their reaction with OH and the OH distribution. Local abundance of OH is controlled mainly by local abundances of NOx, CO, CH4 and higher hydrocarbons, ozone, water vapour, as well as the intensity of solar UV radiation at wavelengths shorter than 0.310 µm. New laboratory and field work also shows significant formation of O(1D) from ozone photolysis in the wavelength range between 0.310 µm and 0.350 µm (Matsumi et al., 2002; Hofzumahaus et al., 2004). The primary source of tropospheric OH is a pair of reactions starting with the photodissociation of ozone by solar UV radiation. Show
Additionally, in the remote, and in particular upper, troposphere, photodissociation of oxygenated volatile organic chemicals such as peroxides, acetone and other ketones, alcohols, and aldehydes may be the dominant sources of OH radical (e.g., Müller and Brasseur, 1999; Collins et al., 1999; Jaeglé et al., 2001; Tie et al., 2003; Singh et al., 2004). Over continents, measurements in the lower troposphere suggest that processing of unsaturated hydrocarbons or photolysis of carbonyls can also sustain a large pool of radicals (e.g., Handisides et al., 2003; Heard et al., 2004). Furthermore, the net formation of OH by photolysis of nitrous acid (HONO) was found to be the dominant OH radical source in urban atmospheres (e.g., Ren et al., 2003) and in a forest canopy (Kleffmann et al., 2005). The hydroxyl radical reacts with many atmospheric trace gases, in most cases as the first and rate-determining step of a reaction chain that leads to more or less complete oxidation of the compound. These chains often lead to formation of HO2, which then reacts with ozone or NO to recycle back to OH. Tropospheric OH and HO2 are lost through radical-radical reactions leading to the formation of peroxides or with NO2 to form nitric acid (HNO3). Sources and sinks of OH involve most of the fast photochemistry of the troposphere. Bringing the outdoors indoorsHydroxyls are nature’s way of decontaminating our environment and are the reason our environment remains safe for all living things
When hydroxyls are created, they immediately seek out and react with contaminants in the air and on surfaces. These reactions happen within seconds and break down both tiny structures, such as viruses and bacteria, and larger molecules, such as volatile organic compounds (VOCs), so well that hydroxyls are often called 'Nature’s Detergent' a term coined by Nobel Prize winning chemist Paul J. Crutzen. But nature’s detergent is mostly absent from indoor air and however hard and often you clean, bacteria and viruses constantly build up in the air and on surfaces, allergens remain active and smells stay smelly. Hydroxyls are why you are unlikely to catch infections outdoors and what gives ‘fresh air’ that clean and refreshing feel that we all love! Atmospheric creation of hydroxylsHydroxyls are naturally created by interactions between sunlight, water, and plants Hydroxyls are created in the atmosphere both as part of the continual breakdown of aromatic oils secreted into the air by plants everywhere and, during daylight hours, by the photochemical reaction which occurs in the atmosphere where different wavelengths of light interact with water and other chemicals.
The atmospheric cleansing and sanitising cycleHydroxyls power the Earth’s atmospheric cleansing and sanitising cycle and keep our atmosphere clean and liveable
Hydroxyls:
Hydroxyls attack harmful contaminants, but not us!Humans, animals, and plants have evolved over millennia to co-exist with hydroxyls and their reaction by-products. Atmospheric hydroxyls cannot enter the blood stream or tissues within the body, because skin and mucosal membranes have evolved to provide a protective barrier. Simply put, Airora is the future of clean, safe indoor airComing soon, keep up to date ... How are hydroxyl radicals formed in the atmosphere?OH is formed in the atmosphere when ultraviolet light (UV) from the sun strikes ozone in the presence of water vapour (H2O). The initial reaction involves the photolysis of O3 by solar radiation. Then the oxygen atom (O) reacts with water vapour to produce two OH radicals.
What forms the hydroxyl radical?Hydroxyl radical is the most reactive free radical and can be formed from ·O2– and H2O2 in the presence of metal ions such as copper or iron. Hydroxyl radicals have the highest 1-electron reduction potential and are primarily responsible for the cytotoxic effect in aerobic organism.
What is the role of hydroxyl radicals in atmosphere?The hydroxyl (OH) radical is the key oxidant in the global atmosphere as it controls the concentrations of toxic gases like carbon monoxide and climate relevant gases like methane.
Where are hydroxyl radicals found?The hydroxyl radical (OH) is an important chemical species throughout the atmosphere. In the troposphere it is the primary oxidant of both natural and anthropogenic hydrocarbons, leading to the production of pollutant ozone. In the stratosphere and mesosphere, OH is key catalyst of ozone destruction.
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