An emission inventory of ozone precursors developed for the year 1991 and 2001 is used in a Chemistry-Transport Model (MOZART) to examine the tropospheric changes in ozone and its precursors that have occurred during the 1990s in the geographical region of India in response to enhanced human activities. The maximum variation in ozone concentration near the surface is found to be around 5--10 ppbv. It reaches 5--7% in the lower part of the free troposphere and 3--5% in the upper troposphere. The maximum decadal increase in CO and NOx is about 50--70 ppbv (10--18%) and 0.5--1.5 ppbv (20--50%), respectively in the boundary layer. However, in most of the troposphere, the relative magnitude reduces with height and becomes less then 5% above 10 km. The variation in some of the volatile organic compounds is found to be significant.