The ozone layer is a layer of the atmosphere that contains relatively high concentrations of the gas ozone. The ozone layer absorbs 95-99% of the high frequency ultraviolet rays that come from sunlight, thus protecting life on earth from harmful exposure. In the 1970's and 1980's, chemicals known as CFCs, or chlorofluorocarbons, were implicated in the destruction of that vital atmospheric layer that prevents most of the harmful ultraviolet light from the sun from penetrating our atmosphere. There was a big push in the '70s and '80s to ban these chemicals which were used extensively in refrigeration and aerosols. As of 2009, there appears to be a reduction the size of the hole in the ozone, indicationg a possible closure in 30-40 years. However, recent evidence from NOAA researchers suggests that the replacement chemicals (HFCs) may be contributors in global warming.