In 2007, the City of Toronto adopted the target of reducing greenhouse gas (GHG) emissions across Toronto by 80% by the year 2050, relative to 1990 levels. The purpose of the report is to assist Toronto Public Health to better understand the health benefits, and any negative health impacts (harms), of GHG-reduction actions that could be taken to in Toronto. This report also provides input to TransformTO, a project led by the City of Toronto Environment and Energy Division and the Toronto Atmospheric Fund. The goal of TransformTO is to identify a path that will lead Toronto to a low-carbon future, while maximizing health, equity and prosperity.