Abstract

Background tropospheric ozone levels have doubled since 1900 [1], and are presently increasing at a rate of 1 % per year[2]. Of all trace gases in the lower atmosphere, ozone has reached concentration levels closest to proven toxic levels on man[3]. Crop yield in the Netherlands is estimated to be lower by 3 to 4% (300-400 million US $) due to higher ozone levels during the growth season[4]. Column (i.e. mainly stratospheric) ozone levels at northern hemisphere mid latitudes have gone down by 5 to 6% between 1970 and 1991 [5]. The expected increased exposure of the earth surface to UV-B has many adverse effects on man and environment[6]. The changing vertical distribution of ozone may be reflected in climate changes as well[5].

© 1993 Optical Society of America