The ozone layer acts to protect life on Earth by blocking harmful ultraviolet rays from the sun. The "ozone hole" is a severe depletion of the ozone layer high above Antarctica. It is primarily caused by human-produced compounds that release chlorine and bromine gases into the stratosphere. This Infographic shows the ozone hole, one from each month, as observed by the National Ocean and Atmospheric Administration (NOAA) satellites that orbit the poles. This was the largest ozone hole ever observed.