The Nimbus-7 TOMS version 6 data, corrected for the instrument degradation, are analyzed to delineate the solar UV related changes in total ozone (TOZ) against background signals of dynamical origin. It is shown that the solar UV related change in TOZ over a solar cycle is about 1.5 percent that may be attributed to about 6 percent change in the solar UV flux near 200 nm. This estimate is also consistent with the solar UV related changes in TOZ over a time scale of a solar rotation. In the solar rotation case, ozone lags the solar UV by 3--4 days and its sensitivity to solar UV change is a factor of 2--3 less than for the solar cycle case. Both these effects are attributed to chemical time constants in the lower stratosphere that are comparable to the period of a solar rotation. ¿ American Geophysical Union 1991