Lower stratospheric in situ observations are used to quantify both the accumulated ozone loss and the ozone chemical loss rates in the Arctic polar vortex during the 1999–2000 winter. Multiple long-lived trace gas correlations are used to identify parcels in the inner Arctic vortex whose chemical loss rates are unaffected by extra-vortex intrusions. Ozone-tracer correlations are then used to calculate ozone chemical loss rates. During the late winter the ozone chemical loss rate is found to be −46±6 (1σ) ppbv/day. By mid-March 2000, the accumulated ozone chemical loss is 58±4% in the lower stratosphere near 450 K potential temperature (∼19 km altitude).