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This is why ozone holes first formed, and are deeper, over Antarctica. Early models failed to take PSCs into account and predicted a gradual global depletion, which is why the sudden Antarctic ozone hole was such a surprise to many scientists. [28] [29] [30] It is more accurate to speak of ozone depletion in middle latitudes rather than holes.
The ozone hole was much more seen as a "hot issue" and imminent risk compared to global climate change, [13] as lay people feared a depletion of the ozone layer (ozone shield) risked increasing severe consequences such as skin cancer, cataracts, [23] damage to plants, and reduction of plankton populations in the ocean's photic zone. This was ...
Ozone remains depleted in the midlatitudes of both hemispheres. The global-average total column ozone amount for the period 1997-2001 was approximately 3% below the pre-1980 average values. Models capture the observed long-term ozone changes in northern and southern midlatitudes.
Its use as a food dye was legalized in the US by the Pure Food and Drug Act of 1906. [6] By early 1920s, it was produced mainly for the food industry, [ 7 ] with 2,170 pounds (0.98 t) made in America in 1924, [ 8 ] rising to 9,468 pounds (4.29 t) in 1938 [ 9 ] and approximately 50 tons in 1967.
The amount of ozone manufactured for use in the food and other industries is reflected in the considerable effort placed on producing it efficiently in high performance ozone generators. [17] Where non-targeted antibiotic action is required, such as in water purification, it is widely used.
Despite their short lifespan, VSLS have been shown to contribute significantly towards the depletion of the ozone layer, particularly in the lower stratosphere above mid-latitude areas. [6] One study has shown that every five additional parts per trillion by volume (pptv) of VSLS in the atmosphere reducesthe global ozone column by about 1.3%. [7]
Ozone in the troposhere is determined by photochemical production and destruction, dry deposition and cross-tropopause transport of ozone from the stratosphere. [2] In the Arctic troposphere, transport and photochemical reactions involving nitrogen oxides and volatile organic compounds (VOCs) as a result of human emissions also produce ozone resulting in a background mixing ratio of 30 to 50 ...
The United Nations designates a specific theme each year for the International Day for the Preservation of the Ozone Layer to highlight different facets of ozone protection. 2015: 30 Years of Healing the Ozone Together. [6] 2016: Ozone and climate: Restored by a world united. [7] 2017: Caring for all life under the sun. [8] 2018: Keep Cool and ...