A differentiated urban metabolism methodology is developed to quantify inequality and informsocial equity in urban infrastructure strategies aimed at mitigating local in-boundary PM2.5 andco-beneficially reducing transboundary greenhouse gas (GHG) emissions. The method differentiates community-wide local PM2.5 and transboundary GHG emission contributions byhouseholds of different income strata, alongside commercial and industrial activities. Applied inthree Indian cities (Delhi, Coimbatore, and Rajkot) through development of new data sets, methodyields key insights that across all three cities, top-20% highest-income households dominatedmotorized transportation, electricity, and construction activities, while poorest-20% homesdominated biomass and kerosene use, resulting in the top-20% households contributing more thanthree times GHGs as the bottom-20% homes. Further, after including commercial and industrialusers, top-20% households contributed as much or more in-boundary PM2.5 emissions than allcommercial OR all industrial emitters (e.g. Delhis top-20% homes contributed 21% ofin-boundary PM2.5 similar to industries at 21%. These results enabled co-benefit analysis ofvarious infrastructure transition strategies on the horizon, finding only three could yield bothsignificant GHG and PM2.5 reductions (>2%-each): (a) Modest 10% efficiency improvementsamong top-20% households, industry and commercial sectors, requiring a focus on wealthiesthomes; (b) Phasing out all biomass and kerosene use within cities (impacting poorest);(c) Replacing gas and diesel vehicles with renewable electric vehicles. The differentiated PM2.5 andGHG emissions data-informed social equity in the design of the three co-beneficial infrastructuretransitions by: (a)-prioritizing free/subsidized clean cooking fuels to poorest homes; (b)-increasingelectricity block rates and behavioral nudging for wealthiest homes; and, (c)-prioritizingelectrification of mass transit and promoting electric two-wheelers ahead of providing subsidies forelectric cars, where the free-rider phenomenon can occur, which benefits wealthiest homes. Themethodology is broadly translatable to cities worldwide, while the policy insights are relevant torapidly urbanizing Asia and Africa to advance clean, low-carbon urban infrastructure transitions.