The ozone hole is a region of depleted ozone in the stratosphere over the Antarctic. The ozone hole is usually noticeable from August to October. The hole was first discovered in the 1980s and immediately after it was discovered countries around the world decided to re mediate the problem by signing the Montreal protocol. The Montreal Protocol which was finalized in 1987 is a global agreement to protect the ozone layer by phasing out ozone depleting substances such as chlorofluorocarbons (CFCs).
What is Ozone?
Ozone is a gas that is composed of three oxygen atoms, and naturally occurs in the stratosphere which is referred to as “good ozone”. Ozone is essential to life on earth because it shields earth from harmful ultraviolet radiation. Ozone present in the stratosphere forms naturally through O2 splitting apart by sunlight to form individual oxygen atoms. However ozone can also occur in the lower atmosphere, or troposphere, and become toxic to plants and animals. According the EPA exposure to ozone levels greater than 70 parts per billion for 8 or more hours can be extremely unhealthy.
The ozone hole is caused mainly by the emission of CFCs into the atmosphere. CFCs are mainly emitted from refrigeration devices and propellant processes into the lower atmosphere. However CFCs pose a major problem because they’re extremely stable meaning they can stay within the atmosphere for decades. This long life span allows CFCs to travel into the stratosphere and release chlorine atoms which destroys ozone. Additionally the reaction between the chlorine atom and ozone leaves the chlorine atom unchanged allowing it destroy high amounts of ozone.
But there is good news. Susan Strahan, an atmospheric scientist from NASA’s Goddard Space Flight Center, stated that there is a less ozone being depleted due to less chlorine from CFCs being seen within the ozone hole. Strahan’s conclusion is support with data from the Microwave Limb Sounder on the Aura Satellite which helped scientists to gather information about the amount of hydrochloric acid in the stratosphere. Hydrchloric acid is a chemical that is formed after chlorine destroys ozone. By measuring the level of hydrochloric acid researchers determined that the chlorine within the atmosphere is decreasing by 0.8% per year.