Situated between six and 40 miles above Earth, the stratospheric (or good) ozone layer protects the planet from potentially dangerous ultraviolet rays. Ozone contains three atoms of oxygen that dynamically shape and dissolve the ozone layer when it interacts with ultraviolet rays, according to "National Geographic." This continual cycle helps the ozone layer protect the planet by absorbing between 97 and 99 percent of the sun’s ultraviolet rays, according to the Climate Institute.
Manmade chemicals have depleted the ozone layer by interrupting the ozone cycle by destroying the ozone layer faster than the rate of rebuilding. Chlorofluorocarbons (CFC), for example, are a large contributor to the disruption of this cycle. According to the U.S. Environmental Protection Agency (EPA), these substances used to be considered a kind of dream substance to work with. CFCs were stable, nontoxic and nonflammable chemicals that found their way into many products, ranging from refrigerants to spray aerosol. Unfortunately, many of these chemicals made their way to the stratosphere, where ultraviolet rays broke down CFCs to release chlorine, according to "National Geographic." In turn, chlorine atoms broke down ozone. According to the EPA, one atom of chlorine is capable of destroying more than 100,000 molecules of ozone.
Other Environmental Contributors
Halons and methyl bromide also play a role in the depletion of the ozone layer. Firefighters use halons in fire extinguishers, and farmers use methyl bromide as a fumigant. Both chemicals contribute to ozone depletion by releasing the chemical bromine, according to the National Oceanic and Atmospheric Administration (NOAA). Like CFCs, bromine also interacts with the ozone layer by destroying ozone molecules.
Destruction of the ozone layer influences health in many ways. More ultraviolet radiation is reaching Earth because of the depletion of the ozone layer, according to the World Health Organization (WHO). WHO notes that higher levels of ultraviolet radiation increase the risk for sunburn, skin damage and skin cancer in humans. These rays also potentially damage the eyes, contributing to cataracts and macular degeneration. The effects aren’t limited to human health. According to the EPA, excess ultraviolet radiation may damage crops and harm marine life.
Future of Ozone Depletion
Because of the banning of CFCs in many countries, the levels of chlorine circulating in the ozone layer are currently falling, according to the EPA. Fortunately, the ozone layer can natural replete itself. The EPA estimates that this process can take around 50 years.