The history of the discovery and measurement of ozone in the atmosphere is described. Sounding balloon determinations made in 1949 were compared with the generally accepted standards of 1935. The total ozone concentration above 8 km was determined as 0.296 cm at standard temperature and pressure. In spite of the difference in the absolute quantity of ozone encountered in 1949 as compared to 1935, the relative amounts of ozone as a function of altitude were very similar. The maximum path of ozone per km of height occurred at about a 21.5-km altitude and was 0.026 cm at standard temperature and pressure. Air taken in at this altitude and compressed without decomposing the ozone would retain the same relative concentration. This value is within the widespread limits of ozone toxicity.