Exceptionally low polar ozone levels

The ESA (European Space Agency) has announced that in the month of March the Envisat satellite has measured a new record low level of ozone over the Arctic. The level measured, the lowest ever, is due to the exceptional intensity of the polar vortex: a set of freezing cold winds that has isolated the atmosphere over the North Pole preventing it from mixing with air from other latitudes richer in ozone. The polar vortex is active throughout winter and breaks up in spring. This year, however, the vortex has lasted longer and the Arctic winter has been colder. The chlorofluorocarbons (CFCs) present in the isolated atmosphere react with sunlight and decompose releasing chlorine atoms which are directly responsible for ozone destruction. Ozone is a gas made up of three atoms of oxygen that is prevalently concentrated in the atmospheric layer that extends above the troposphere, between 15 and 35 kilometres above the Earth’s surface. Its importance is due to the fact that it protects the Earth’s surface from the ultraviolet rays of the Sun that are dangerous to life when very intense. CFCs, which are used as propellants in spray cans and for cooling and refrigeration and which are responsible for the thinning of the ozonosphere, have been banned in numerous countries and global production has diminished drastically. However, they are still present in the atmosphere and in exceptional meteorological conditions, such as the one mentioned above, their negative effect can still be felt.