Eli5: how can earth ozone layers heal itself even with our high pollution level?
Ozone is constantly being created in the upper atmosphere when ultraviolet light from the sun interacts with molecular oxygen. The ozone layer was being damaged because we were emitting ozone depleting chemicals faster than ozone was created naturally by this process. All we had to do was stop emitting ozone-depleting chemicals (which we did) and over time, new ozone forms naturally. It’s only those specific chemicals that damage the ozone layer, not all pollution in general. Now, the ozone layer is largely replenished from its low point in the 1980’s.
It’s a very specific kind of pollution that depletes atmospheric ozone – a few types of free chlorofluorocarbons.
These “CFCs” were used as consumer-grade refrigerants and propellants in a lot of different applications up through the 1990s or so, but have since been replaced with similar compounds that have acceptably close performance but do not react with ozone.
With the target pollution greatly mitigated, the natural ozone production rate in the upper atmosphere has been able to repair the damage.
This was possible because it was a relatively cheap and easy fix to coordinate globally.
It is the type of pollution that affects the ozone layer that is key for this topic. We realized back in the 70’s that fluorocarbons that we produced for use in things like air conditioners or the propellants used in deodorant sprays, were actually destroying the ozone layer. It took years to put into place and develop alternatives but a concerted effort was put into place to remove these substances from products. By the early 90’s we were developing refrigerants in air conditioners and refrigeration systems that did not cause these ozone-depleting issues. Fast forward a few decades and whoa, it’s working!
Ozone layer is not damaged by all pollution, only by specific chemicals that reacts with ozone in a particular, a chain reaction-like way. Majority of those chemicals aren’t pollutants from industry, but industrial chemicals that have leaked into the atmosphere due to lack of regulations and accidental discharges. Car A/C refrigerants for example.
So as long as we stop leakage of those particular chemicals (bybiposing strict controls over handling, or replacing them with different ones), ozone layer helps over time.
The degradation of the ozone layer was caused by a very specific set of gasses that were in use in spraycans and AC units. These CFC gases are no longer being released in the atmosphere.
CO2 and other pollutants don’t affect the ozone layer.