When scientists first noticed the hole that had formed in the ozone layer, many believed that chloro-fluorocarbons (CFCs) were the cause. These chemicals were used in a wide variety of applications, including packing materials, air conditioning units and aerosol sprays. When CFCs make their way into the atmosphere, they get broken down by the sun's ultraviolet rays -- and release ozone-destroying chlorine atoms.
The ozone layer is an essential shield from the sun's radiation. Without it, the planet would not be protected from harmful radiation from the sun. Some of the side effects from unmitigated sun radiation would include damage to wildlife and the environment, along with skin cancer and cataracts.
Under the Montreal Protocol, which was introduced in 1989, these ozone-killing chemicals were put to bed. Around the world, CFCs were phased out. But, was it too late?
In 2005, NASA began permanent surveillance of the hole in the ozone layer, using its Aura satellite to monitor its status. Ozone depletion occurs in cold weather -- so it can differ from year to year and makes it much more challenging to study. Past analyses have suggested that ozone depletion has been dropping, but now NASA has finally been able to confirm that the Earth's natural "sunscreen" layer is finally healing.
In a recent study using readings of the ozone's chemical composition gathered from Aura, scientists have found that the hole is actually decreasing in size. The research, led by Dr. Susan Strahan of Nasa's Goddard Space Flight Centre in Greenbelt, Maryland, also reportedly suggests that a reduction atmospheric CFC levels is responsible for helping the ozone layer heal.
Strahan wrote, "All of this is evidence that the Montreal Protocol is working - the chlorine is decreasing in the Antarctic stratosphere, and the ozone destruction is decreasing along with it."
According to the study, the amount of ozone-killing chlorine in the atmosphere over Antarctica is dropping by a rate of 0.8 percent each year. Since the Montreal Protocol was initiated, ozone depletion has been reduced by approximately 20 percent -- not too shabby.
Researchers believe that the hole over the Antarctic could potentially be fully repaired by the year 2060. Although, co-author Dr. Ann Douglass cautions that even in 2080, there may still be a small hole. "CFCs have lifetimes from 50 to 100 years, so they linger in the atmosphere for a very long time," she explained.
While the reduction in CFCs is no doubt good for the environment (especially the ozone layer), these hazardous chemicals have unfortunately been replaced by more toxic chemicals. Since CFCs are now off limits, many manufacturers have turned to hydrofluorocarbons -- which contain fluoride gas. Hydrofluorocarbons (HFCs) are now used in refrigerants, aerosol sprays and other goods -- but there are many concerns about their use, particularly regarding their environmental effects.
While the ozone layer may be healing, there is no shortage of environmental toxins out there in the world -- it's not just CFCs and HFCs. Pesticides, herbicides and other chemicals have been linked to an array of problems for the environment. [Related: Read more stories about what's helping and harming our environment at Environ.news.]
Will the closing of the ozone layer inspire more bans on toxic chemicals? After all, if the ozone layer can heal up, perhaps it's not too late for the rest of the planet.
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