An estimate of tropospheric ozone concentrations was obtained from the difference in the Total Ozone Mapping Spectrometer (TOMS) data between the high Andes and the Pacific Ocean. From 1979 to 1992 the tropospheric ozone concentration apparently increased by 1.48 +/- 0.40 percent per year or 0.21 +/- 0.06 Dobson unit per year over South America and the surrounding oceans. An increase in biomass burning in the Southern Hemisphere can account for this trend in tropospheric ozone concentrations.