How do protect of ozone layer?

The ozone layer:

 The ozone layer is a natural layer of gas in the upper atmosphere that protects humans and other living things from harmful ultraviolet (UV) radiation from the sun.

  Although ozone is present in small concentrations throughout the atmosphere, most (around 90%) exists in the stratosphere, a layer 10 to 50 kilometers above the Earth’s surface. The ozone layer filters out most of the sun's harmful UV radiation and is therefore crucial to life on Earth.

  World governments agreed in the late 1980s to protect the Earth’s ozone layer by phasing out ozone-depleting substances emitted by human activities, under the Montreal Protocol. In Europe, the Protocol is implemented through EU-wide legislation that not only meets its objectives but also contains stricter, more ambitious measures.

Global action taken under the Montreal Protocol has halted the depletion of the ozone layer and allowed it to start recovering, but much remains to be done to ensure a steady recovery.

 Ozone depletion:

  Scientists discovered in the 1970s that the ozone layer was being depleted.

    Atmospheric concentrations of ozone vary naturally depending on temperature, weather, latitude and altitude, while substances ejected by natural events such as volcanic eruptions can also affect ozone levels.

However, these natural phenomena could not explain the levels of depletion observed, and scientific evidence revealed that certain man-made chemicals were the cause. These ozone-depleting substances were mostly introduced in the 1970s in a wide range of industrial and consumer applications, mainly refrigerators, air conditioners and fire extinguishers.

 Ozone hole:

   Ozone depletion is greatest at the South Pole. It occurs mainly in late winter and early spring (August-November) and peak depletion usually occurs in early October, when ozone is often completely destroyed in large areas. 

  This severe depletion creates the so-called “ozone hole” that can be seen in images of Antarctic ozone, made using satellite observations. In most years, the maximum area of the hole is bigger than the Antarctic continent itself. Although ozone losses are less radical in the Northern Hemisphere, significant thinning of the ozone layer is also observed, over the Arctic and even over continental Europe.

Most of the ozone-depleting substances emitted by human activities remain in the stratosphere for decades, meaning that ozone layer recovery is a very slow, long process. The hole grew in the years following ratification of the Montreal Protocol, due to the lag caused by the fact that ozone-depleting substances remain in the stratosphere for a long time. The maximum size of the ozone hole is now decreasing.

  Effects of ozone depletion for humans and the environment:

    Ozone layer depletion causes increased UV radiation levels at the Earth's surface, which is damaging to human health.

    Negative effects include increases in certain types of skin cancers, eye cataracts and immune deficiency disorders. UV radiation also affects terrestrial and aquatic ecosystems, altering growth, food chains and biochemical cycles. Aquatic life just below the water’s surface, the basis of the food chain, is particularly adversely affected by high UV levels. UV rays also affect plant growth, reducing agricultural productivity.

Health Effects:

  Increased UV levels at the earth's surface are damaging to human health. The negative effects include increases in the incidence of certain types of skin cancers, eye cataracts and immune deficiency disorders. Increased penetration of UV results in additional production of ground level ozone, which causes respiratory illnesses.

   Environmental Effects:

UV affects terrestrial and aquatic ecosystems, altering growth, food chains and biochemical cycles. In particular, aquatic life occurring just below the surface of the water, which forms the basis of the food chain, is adversely affected by high levels of UV radiation. UV rays also have adverse effects on plant growth, thus reducing agricultural productivity. Furthermore, depletion of stratospheric ozone also alters the temperature distribution in the atmosphere, resulting in a variety of environmental and climatic impacts.