Equivalent effective stratospheric chlorine Equivalent effective stratospheric chlorine Equivalent effective stratospheric chlorine (EESC) provides an estimate of the total effective amount of halogens (chlorine and bromine) in the stratosphere. It is calculated from emission of chlorofluorocarbon and related halogenated compounds into the troposphere (lower atmosphere) and their efficiency in contributing to stratospheric ozone depletion (ozone depletion potential, ODP), and by making assumptions on transport times into the upper atmosphere (stratosphere). This parameter is used to quantify man-made ozone depletion and its changes with time. As a consequence of the Montreal Protocol and its amendments phasing out ozone-depleting substances (ODS), the EESC reached maximum in
Abundance of the chemical elements 0.75% is made up of the next five elements: potassium (K), sulfur (S), chlorine (Cl), sodium (Na), and magnesium (Mg). CHNOPS for short. Only 17 elements are known for certain to be necessary to human life, with one additional element (fluorine) thought to be helpful for tooth enamel strength. A few more trace elements may play some role in the health of mammals. Boron and silicon are notably necessary for plants but have uncertain roles in animals. The elements aluminium and silicon, although very common in the earth's crust, are conspicuously rare in the human body. Below is a periodic