The changes in chemical partitioning and stratospheric O3 abundance due to the recently measured rate coefficients for the O+NO2, OH+HNO3, and OH+NO2 reactions are examined using a two-dimensional model. The rate constant changes increase NOx abundance (up to 40%) and NOx-catalyzed O3 destruction, and extend down by several kilometers the altitude region where NOx dominates catalytic O3 destruction. Reductions in the abundance of HOx (10--30%) and ClOx (20--40%) in the lower stratosphere partially buffer the effect on column O3 amount. Column O3 at middle and high latitudes is reduced by 2--10% depending on season for current halogen levels. The model derived long-term O3 trend at midlatitudes due to increases in anthropogenic halogens is reduced by approximately 30%. ¿ 1999 American Geophysical Union