Resumen
In this paper we examine measurements of the thickness of the total ozone column between 1986 and 1989 in Mexico City. We consider the contribution of the surface ozone in measurements of the total ozone column made with the Dobson Spectrophotometer located at the Solar Radiation Laboratory (National University), in the southwest of Mexico City. We consider different depths of the mixing layer depending on the season and we compare our results with those reported for Mauna Loa in Hawaii and Poona in India, at the same latitude as Mexico City. In conclusion we confirm that in highly polluted areas the surface ozone has an important effect on measurements of the total ozone column.