WHO IS THROWING CFC - 11 INTO THE ATMOSPHERE?

Chlorofluorocarbons (CFCs) are volatile derivatives of hydrocarbons gotten by swapping hydrogen atoms by chlorine (Cl), and fluorine (F). they are mainly used in the refrigeration industry as well as a propellant for aerosol spray cans. they are gases which stay in the atmosphere from 50 to 200 years. when they reach the stratosphere, they dissociate and start depleting the Ozone layer. The ozone layer protects the Earth from the sun's harmful UV radiation. It was discovered that ozone levels were declining and this caused a wave of concern in the 1980s about rising rates of skin cancer. Due to this fact, a lot of investigations were carried out successfully in order to get alternatives to this gases which widened the ozone hole. For instance, they found the Hydrochlorofluorocarbons (HCFC) as well as the Hydrofluorocarbons (HFC) and the Hydrocarbons, which have already replaced CFCs in spray cans. In 1987, The Montreal Protocol was signed. It was an international agreement whose goal was to end production of ozone-destroying substances, such as the CFCs. Since then, the rate of decline of atmospheric CFC-11 concentrations has been constant from 2002 to 2012, which has significantly contributed in the ozone layer improvement. However, in 2016, emissions of CFC-11 had climbed 25% since 2012, in both northern and southern hemispheres, though it’s been higher in the northern one. The decline of CFC emissions has slowed down, which has catched the attention of the scientists, and a research on this topic was led by U.S. researchers with NOAA, with help from scientists in the Netherlands and the United Kingdom. By taking into account air flow into the regions where their monitoring stations were placed, they concluded East Asia was the most likely source of this unexpected emissions. They considered several possible explanations for the growth, that didn't include an intentional release of this gases, as a change in atmospheric patterns, an increase in the rate of demolition of buildings containing old residues of CFC-11, or accidental production. But their conclusion showed that this increase couldn't be explained by this sources. Still, the cause remains a mystery for now, and it's crucial for the ozone layer recovery to find the source and eliminate it, though, in the meantime, it's leaving it more vulnerable to other threats. Ana Vargas Baco