2009 Ozone-Depleting Gas Index

ESRL updates index to guide and monitor the recovery of the ozone layer

In September, ESRL’s Global Monitoring Division published the annual Ozone Depleting Gas Index (ODGI), which is a measure of overall atmospheric abundance of ozone-depleting chemicals called halons. ODGI is defined as 100 at the peak of halon levels (in 1994), and has been dropping steadily, due to the actions of an international treaty, the Montreal Protocol, and its amendments. More: http://www.esrl.noaa.gov/gmd/odgi/.