In its Third Assessment Report (IPCC 2001), the Intergovernmental Panel on Climate Change concluded that climate policies designed to mitigate greenhouse gas emissions area win-win proposition. They relied on models that predict climate policy will bring significant benefits for developed countries, and even larger benefits for developing countries. The rationale behind these findings is that climate policies will reduce fossil fuel consumption and their associated local air pollution, hence reducing health impacts of poor air quality yielding "ancillary benefits" (i.e. indirect or side benefits) offsetting, and at times exceeding, the mitigation costs. IPCC's assertions are reflective of conditions where fossil fuel consumption is the major determinant of urban outdoor air quality, and indoor and outdoor air quality are strongly correlated. Our research examines the validity of the ancillary benefit models in developing countries where the continued use of biomass and household coal determine indoor air quality and are estimated to result in 1.6 million deaths annually. We use a case study analysis for India to illustrate linkages between climate mitigation policy and household indoor air pollution. The significance of this research is to incorporate biomass, non-commercial household energy sources, and indoor air pollution in the analysis of international climate policy impacts.