Economic growth and performance is monitored through the gross domestic product (GDP) of a nation. It has long been recognized that the traditionally computed GDP does not account for gains and losses observed due to the consumption of natural resources and environmental services. Hence, the objective of this study is to modify the Turkish GDP by taking social cost associated with air pollution into consideration. To this end health benefits and economic costs of air-quality improvement are estimated. The computations are based on the dose-response coefficients reported in several studies. The results indicate that a decrease in PM10 and SO2 levels to the WHO guideline would have resulted in a total of 48.309 x 1010 and 153.38 x 1010 Turkish lira savings in 1990 and 1993, respectively. These correspond to 0.12% and 0.08% of 1990 and 1993 GDPs, respectively.