Evolution of ozone´s layer hole

Ozone depletion was first detected in Antarctica in 1977. In 1985, the ozone layer over this region has lessened by 40%., that was when he began to speak of "hole" in the ozone layer.

The hole of ozone layer in September 2000 reached a record lenght equal to three times the size of the USA, 29 million square kilometers. (Click to see the link)

The alarming increase of hole in the ozone layer recorded in the year 2000 did not seem consistent with the decreased use of chemicals "chlorofluorocarbon" also called CFC, wich has been achieved in recent years to combat the effect emissions. But forecasters say there are also climatic factors that aggravate the problem. At the time the increased fotmation of a cloud type of "polar stratospheric clouds" with ice crystals act as accelerators of the process.

Something similar but in reverse has happened this year in September and against all odds the hole in the ozone layer is momentarily divided in two, reducing its total lenght, reaching the same size at it did in 1998. Experts say this improvement has occurred because the temperatures higher than normal, and a circular feature of winds in the stratosphere over Antarctica.

                                                     (Click to enlarge)

The Ozone´s Layer

1.Effects on human health because reduced ozone:

   - Skin cancer. Today it is estimated that skin cancer rates increased due to stratospheric ozone depletion. The most common type of of skin cancer, called non-melanoma causes exposure to UV-B radiation for several years. There are already people who have received the dose of UV-B can cause this type of cancer.

   - The immune system. The defenses of a person to fight infection depends on the strenght of your immune system. It is known that exposure to ultraviolet light reduces the effectiveness of the immune system, not only related to skin infections but also with those verified in others parts of the body. 

     Exposure to UV-B radiation may well make the immune system to tolerate the disease rather than against it. This could mean the uselessness of vaccination programs in both industrialized and developing countries.

2. Effects on aquatic ecosystems: 

The loss of phytoplankton, the base of marine food chain, has been observed as a result of increased ultraviolet radiation. Under the ozone hole in Antartic, phytoplankton productivity decreased between 6-12%.

UNEP indicated that 16% of ozone depletion could result in a 5% loss of phytoplankton, wich would mean a loss of 7 million tonnes of fish per year, about 7% of world fish production. 30% of human consumption of protein from the sea, this proportion rises further in developing countries.

3. Effects on terrestrial ecosystems.

- Animals: for some species, increased UV-B involves the formation of skin cancer. This has been studied in goats, cows, dogs, sheep and laboratory animals and is probably saying that this is a feature common to several species. Infections in cattle may be aggravated by increased UV-B radiation.

- Plants: in many plants UV-B radiation can have the following effects: damage alter their shape and plant growth, reduce the growth of trees flowering times change, make plants more vulnerable to disease and produce toxic substances. It could even be losses of biodiversity and species. Among the crops that were reported negative effects due to the incidence of UV-B radiation include soybeans and rice.

4. Effects of air pollution on the ozone´s layer. 

Due to pollution, ozone losses in the upper atmosphere cause UV-B increase the levels of ozone in the earth´s surface, specially in urban and suburban areas, wich are the most contaminated, reaching potentially harmful concentrations (in combination with other pollutants) in the early hours of the day.

5. Source of ozone in the earth´s surface. 
The same ozone molecules that protect us from the sun´s radiation (UV) in the stratosphere can cause health problems in human and animals when they are near the earth´s surface. Ozone in the earth´s surface is formed when gases from vehicles and some other chemicals commonly used in industry is mixed in the presence of strong sunlight. When these ozone concentrations become high enough, they can make breathing difficult, specially in those with asthma and other respiratory diseases.