The long-term trend analysis of the total ozone data for the period 1973--1989 was made for three regions of the USSR. A common negative trend is explained by the eruptions of Fuego and El Chichon as one of two considered reasons, and comparison of the ozone and sulphur dioxide data for Murmansk gives further evidence to the study of De Muer and De Backer, finding that an ozone decrease vanishes when correction for tropospheric SO2 decrease is carried out. The well-known hypothesis about anthropogenic induced depletion of the ozone layer is not confirmed by these data. ¿ American Geophysical Union 1994