Until March 2011 the hole over the Arctic region used to be very small compared with that of the Antarctic.
In a recent development, scientists representing 19 institutions from nine countries discovered that the ozone layer hole over the Arctic region has dramatically expanded to an alarming size during the winter of 2010 – 2011. Their findings stated that due to a high altitude wind pattern called the polar vortex, the region has suffered a loss of as much as 40 percent of ozone in the stratosphere from the start of winter until the end of March 2011, surpassing the previous seasonal loss that recorded only about 30 percent.
The ozone depletion is blamed on a combination of winter that gets much colder and lasts longer than it used to be, and the persistent presence of ozone-depleting man-made chemicals in the atmosphere, the most harmful of which is the chlorofluorocarbons or CFCs. The cold high-altitude weather activated the existing chemicals in the atmosphere. Although the concentration of CFCs in the atmosphere has considerably dropped after its production and consumption were ordered phased out by the Montreal Protocol, its presence still lingers, and will remain in the atmosphere for decades more before it can be contained.
The recent ozone layer depletion in the Arctic is seen to be so much more harmful than that of the Antarctic region. Although the winters in the Antarctic, which are normally longer and colder, and often, have 55 percent ozone depletion, its impact on human health is quite negligible since the region is virtually uninhabited, except for the southern tip of South America, which at times, comes under the ozone hole. The hole in the Arctic, which has become so thin like never before, covered two million square kilometers over Scandinavia, Greenland, northern Canada, and Russia. This means that more of the sun’s harmful ultraviolet B rays can now easily penetrate through the atmosphere and directly hit the people in these areas, exposing them to health hazards, like skin cancer, cataracts, and damage to their immune system.
The ozone layer has been depleting over the years because of the increased level of concentration of free radicals, such as the hy-droxyl radicals, nitric oxide radicals and atomic chlorine, bromine, and the CFCs. The chlorofluorocarbon compounds, which are otherwise very stable in the lower atmosphere of the earth, break down in the stratosphere and release a free chlorine atom due to ultraviolet radiation, and consequently become responsible for almost 80 percent of the total depletion of ozone in the stratosphere. The chain of reaction starts when a free chlorine atom reacts with an ozone molecule to form chlorine monoxide and one molecule of oxygen. The chlorine monoxide then reacts with an ozone molecule to form a chlorine atom and two molecules of oxygen, and then the cycle is repeated over again to eventually deplete the ozone in the stratosphere. This ozone depletion is, therefore, a cause for concern because mankind becomes exposed to strong ultraviolet rays.
However, after scientists discovered the ozone layer hole in the Antarctic region in 1985, a number of governments pushed for stronger measures to reduce production and consumption of the man-made compounds that cause depletion of the ozone in the stratosphere. The United Nation’s Montreal Protocol, which banned these chemicals, has successfully brought down the amount of ozone-depleting gases, albeit gradually.