Due to the fact that many air pollutants and greenhouse gases have common sources and can interact in the atmosphere to form hazardous components, in air quality. The aim of the present thesis is to analyze how thesemitigation measures focusing on climate objectives may have important consequences linkages that they are fully taken into consideration by policy-makers. Basedcould impact results of negotiations on GHG emission targets, supposing on data from the GAINS1 model developed at the IIASA2, we show that the inclusion of avoided abatement costs of air pollutants and avoided impacts on health can significantly change the economic incentives of parties to the UNFCCC3. Most countries see a reduction in their mitigation costs, except for regions which significantly supply the carbon market with permits. The inclusion of ancillary benefits in the assessment of GHG mitigation costs Mechanism credits. However, it is observed that these decreases in carbon also tends to reduce the demand for carbon trading and Clean Development prices do not seem to change significantly the repartition of quantitative abatement efforts among Annex I countries.