This dataset contains ozone measurements from the Ozonesonde instrument in Antarctica, Hawaii, and Fiji taken during the Atom-4 campaign. The Electrochemical Concentration Cell (ECC) Ozonesonde is a balloon-borne instrument that collects ozone concentrations paired with a radiosonde to collect additional meteorological info along a vertical profile (as a result, unlike other ATom data, this dataset is not associated with DC-8). The balloon can ascend to altitudes of 35 km before bursting. Ozone in the stratosphere helps reduce UV radiation that reaches Earth's surface; however, ozone at ground level can negatively influence respiratory health.