A process is presented for reducing the concentration of pollutants in an effluent from the combustion of a carbonaceous fuel. The process comprises introducing a first treatment agent into the effluent at a first temperature zone to reduce the concentration of a first pollutant and introducing a second treatment agent into the effluent at a second temperature zone to reduce the concentration of either the first pollutant or a second pollutant, wherein the first and second treatment agents are introduced under conditions effective to reduce the effluent pollution index.