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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 .
Ozone-oxygen cycle in the ozone layer. The photochemical mechanisms that give rise to the ozone layer were discovered by the British physicist Sydney Chapman in 1930. Ozone in the Earth's stratosphere is created by ultraviolet light striking ordinary oxygen molecules containing two oxygen atoms (O 2), splitting them into individual oxygen atoms (atomic oxygen); the atomic oxygen then combines ...
Ground-level ozone (O 3), also known as surface-level ozone and tropospheric ozone, is a trace gas in the troposphere (the lowest level of the Earth's atmosphere), with an average concentration of 20–30 parts per billion by volume (ppbv), with close to 100 ppbv in polluted areas.
An ozone monitor of this type operates by pulling an air sample from the atmosphere into the machine with an air pump. [3] During one cycle, the ozone monitor will take one air sample through the air inlet, and scrub the ozone from the air; for the next cycle, an air sample bypasses the scrubber and the ozone value calculated.
Ozone was originally found to be damaging to grapes in the 1950s. The US EPA set "oxidants" standards in 1971, which included ozone. These standards were created to reduce agricultural impacts and other related damages. Like lead, ozone requires a reexamination of new findings of health and vegetation effects periodically.
Ventilation with outdoor air containing elevated ozone concentrations may complicate remediation attempts. [69] The WHO standard for ozone concentration is 60 μg/m 3 for long-term exposure and 100 μg/m 3 as the maximum average over an 8-hour period. [29] The EPA standard for ozone concentration is 0.07 ppm average over an 8-hour period. [70]
The largest Antarctic ozone hole recorded (September 2006) 2012 retrospective video by NASA on the Montreal Protocol. The Montreal Protocol on Substances That Deplete the Ozone Layer is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion. It ...
Ozone depletion consists of two related events observed since the late 1970s: a steady lowering of about four percent in the total amount of ozone in Earth's atmosphere, [citation needed] and a much larger springtime decrease in stratospheric ozone (the ozone layer) around Earth's polar regions. [1] The latter phenomenon is referred to as the ...