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Soil and water being splashed by a raindrop. Petrichor (/ ˈ p ɛ t r ɪ k ɔːr / PET-ri-kor) [1] is the earthy scent produced when rain falls on dry soil.The word was coined by Richard Grenfell Thomas from Ancient Greek πέτρα (pétra) 'rock' or πέτρος (pétros) 'stone' and ἰχώρ (ikhṓr), the ethereal fluid that is the blood of the gods in Greek mythology.
Ozone (/ ˈ oʊ z oʊ n /) (or trioxygen) is an inorganic molecule with the chemical formula O 3. It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope O 2, breaking down in the lower atmosphere to O 2 .
Smog, or smoke fog, is a type of intense air pollution.The word "smog" was coined in the early 20th century, and is a portmanteau of the words smoke and fog [1] to refer to smoky fog due to its opacity, and odor. [2]
The Environmental Protection Agency is delaying plans to tighten air quality standards for ground-level ozone — better known as smog — despite a recommendation by a scientific advisory panel ...
[1] [2] These gases contribute to the formation of smog and acid rain, as well as affecting tropospheric ozone. NO x gases are usually produced from the reaction between nitrogen and oxygen during combustion of fuels, such as hydrocarbons, in air; especially at high temperatures, such as in car engines.
Ozone attack will occur at the most sensitive zones in a seal, especially sharp corners where the strain is greatest when the seal is flexing in use. The corners represent stress concentrations, so the tension is at a maximum when the diaphragm of the seal is bent under air pressure. Close-up of ozone crack (using ESEM) in NBR diaphragm seal
Ozone depletion is a separate problem caused by chlorofluorocarbons (CFCs) [231] which have been released into the atmosphere. [232] However, CFCs are strong greenhouse gases. [233] [234] Further, the hole in the ozone layer is shrinking and in 2019 was the smallest it had been since 1982, [235] [236] while global warming continues.
A feasibility study of the ozone formed from the oxidation of nitrogen dioxide in ambient air reported by the WHO suggested that daily deaths of 1 to 2% is attributed to exposure to ozone concentration above 47.3 ppb and exposure above 75.7 ppb is attributed to 3 to 5% increase in daily mortality. A level of 114 ppb was attributed to 5 to 9% ...