Balloonborne measurements of ozone and aerosol concentrations at McMurdo Station in Antarctica in November 1985, indicated large variations, apparently associated with movement of the polar vortex. Extremely low ozone concentrations were observed, on one occasion to altitudes in excess of 30 km. Low ozone was accompanied by the absence of optically active aerosol and an enhancement of condensation nuclei while the opposite was the case with normal ozone. The ozone measurements are consistent with a springtime Antarctic vortex ozone minimum (popularly called the “ozone hole”) and variations in the aerosol size distribution appear to be associated with the thermal history of the relevant air par