How we damage our planet's ozone layer.

in Popular STEM9 days ago

How we damage our planet's ozone layer.




The ozone layer is that part of the atmosphere where ozone molecules block most of the ultraviolet radiation coming from the Sun, without that protection, life on Earth would basically not be possible.


But before I tell you an interesting story, I'm going to ask you a question. Do you have a refrigerator? It would be crazy if you said no, everyone has a refrigerator, it's so common that I'm sure you've never thought about what life was like before they existed.


Food at room temperature spoils quickly every day, they had to go to the market to buy everything fresh that day, some fruits and vegetables can last a few days, but the rest they cooked and ate because there was no other way, you can preserve or brine, but that involves a lot of time, basically the refrigerator changed our lives.


These devices use the magic of thermodynamics to remove heat from the interior where the food is by means of a gas that circulates through a pipe on the walls of the refrigerator, a compressor and an expansion valve are responsible for evaporating and condensing the gas, which will always be carrying the heat from the inside out, which is why the refrigerators have some of their exterior walls hot.




Everything was very good, everyone was very happy with their refrigerators until a leak occurred in the pipe and the gas escaped, poisoning a family. Supertoxic gases such as ammonia, sulfur dioxide and methyl chloride were used, but in the early 1930s, General Motors and Dupont found a refrigerant gas that was not toxic, dichloro difluoromethane better known as Freon 12 and other similar compounds, we are going to call all of these chlorofluorocarbons CFCs.


But the use of CFCs was not limited to refrigerators, they were also used in air conditioning equipment, aerosols and the manufacture of plastic foams. Their main quality is that they are very stable gases, which makes them much less toxic, but that gives them the great disadvantage that they remain in the environment. This gives them time to travel throughout the atmosphere until they reach the highest layers, the stratosphere. In the stratosphere, at altitudes between 10 and 50 km, a lot of ultraviolet radiation.


Here on the surface of the Earth there is also ultraviolet radiation, so you should wear sunscreen or protective clothing and a hat and glasses when you go out in the sun, but the ultraviolet radiation we receive here is practically nothing compared to what the stratosphere receives, apart from that we only get the less energetic ultraviolet radiation, UV-B and UV-A, which can cause melanoma, skin cancer if you don't take care of yourself, but it is not as bad as UV-C and none of that reaches us, we owe that to this molecule with three oxygen atoms, ozone.


If you live in a large city with air quality problems, you have surely heard that ozone is bad, and yes, in fact it is a gas that irritates the respiratory tract and is produced when one of the products of gasoline combustion, nitrogen dioxide, reacts with sunlight. If your city woke up very polluted, especially like now in winter when the atmosphere is very calm and the wind cannot carry away the pollution from the previous day, when the sun rises, its ultraviolet light will begin to transform the dioxide. of nitrogen into ozone and its concentration will be very high during the heaviest hours, affecting people's respiratory tracts.




But not all ozone is bad, in the upper layers of the atmosphere, ozone is produced naturally when oxygen absorbs ultraviolet light and that ozone is the shield that completely blocks UV-C radiation, which is the most dangerous, and blocks most of the UV-B, leaving us the task of protecting ourselves from UVA, which is the least harmful.


In short, ozone at surface level is bad because it affects our respiratory tract, but the ozone up there, which is what is created naturally, is our friend and takes care of us, but our friend was in danger and for decades we did not know it.


We were happy with CFCs because they no longer poisoned families when there was a leak in the refrigerator and we also used them in all types of aerosols such as paints, deodorants and cosmetics, but since they were so stable, they lasted for decades in the atmosphere and began to accumulate in the stratosphere where the ozone is, there CFCs that are so stable in the lower layers of the atmosphere, being exposed to much more ultraviolet radiation, react with this by decomposing, this leaves radical chlorine atoms, that is, with an unpaired electron desperate to join another atom.


As soon as a radical chlorine atom approaches an ozone molecule, it binds and reacts with it, turning it into another compound that does not block ultraviolet radiation, but not only that, that molecule continues to react with other compounds and ultraviolet light to produce more radical chlorine atoms that will continue to destroy more ozone, becoming a chain reaction.



A single molecule of CFCs can destroy many molecules of ozone until by chance it stops with a reaction that no longer produces radical chlorine, and that can take between 50 and 500 years. For decades we continue using CFCs in refrigerators, aerosols and plastic foams and we did not know that we were destroying the only shield that protects us from the deadly UV-C radiation.


In another publication I will tell you how scientists discovered this great error and how the chemical transnationals discredited the research for their own benefits.




The images without reference were created with AI
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