How fast is the Ozone layer being depleted?
Extensive measurements of the Ozone layer by ground-based instruments began in 1957. Since the late 1970s, scientists have taken increasing numbers of measurements of the Ozone layer, using ground-based, balloon- borne and satellite-borne instruments. The measurements have confirmed that Ozone levels are falling almost everywhere in the world. Over the period 1979 to 1994, Ozone over the mid latitudes (30degrees -60degrees) of both hemispheres has been depleted at an average rate of 4-5 per cent per decade. Ozone levels fell faster in the 1980s than in the 1970s, suggesting that Ozone depletion has accelerated.
