Refrigerant
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Refrigerants are working fluids that carry heat from a cold environment to a warm environment while circulating between them. For example, the refrigerant in an air conditioner carries heat from a coo
In the stratosphere, ozone (O3) naturally cycles to oxygen gas (O2) and back when it absorbs solar energy (the Chapman cycle). When CFCs are present, sunlight releases chlorine atoms that catalytically convert O3 to O2: Cl reacts with O3 to form ClO and O2, and ClO is then converted back to Cl, which can destroy further ozone. The net result is more oxygen and less ozone.
Disposable refrigerant gas cylinders, using different colors for different refrigerants. (Current guidelines discourage color-coded cylinders.)
Ozone depletion
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Ozone depletion consists of two related events observed since the late 1970s: a lowered total amount of ozone in Earth's upper atmosphere, and a much larger springtime decrease in stratospheric ozone
Lowest value of ozone measured by TOMS each year in the ozone hole
Ozone hole in North America during 1984 (abnormally warm, reducing ozone depletion) and 1997 (abnormally cold, resulting in increased seasonal depletion). Source: NASA
Ozone levels stabilized in the 1990s following the Montreal Protocol, and have started to recover. They are projected to reach pre-1980 levels before 2075.
Air pollution 3