Habit-locked-in carbon-air-pollutant emissions dominate China's household footprints.

Household consumption is a major driver of global carbon and air-pollutant emissions. As living standards rise, everyday routines become entrenched and reduce the responsiveness of demand to mitigation policies. Consumption-based accounting has traced these burdens through supply chains, yet the scale of emissions that remain locked in by behavioral inertia has stayed poorly quantified. Here we show that locked-in emissions of carbon and air pollutants account for nearly 84% of total household-driven emissions of CO2, PM2.5, NO x , and SO2 across China, far exceeding the contribution of net consumption growth. Food exhibits the highest locked-in share (approximately 97%), followed by residential expenditure (84-86%). Per-capita habit-locked emissions peak in East and North China, with 32-53% of these emissions originating in the production systems of Nei Mongol and Shandong. Scenario analysis to 2035 reveals that under business-as-usual scenario, habit-locked CO2 emissions peak around 2030, while habit-locked air-pollutant emissions decline, whereas the deepest and most balanced reductions, 1285 Mt CO2 together with 218 kt PM2.5, 729 kt SO2, and 126 kt NO x , occur only when carbon-neutrality-oriented policies are paired with attenuated consumption inertia. These findings demonstrate that efficient demand-side synergistic mitigation in China requires systematic substitution of habit-locked carbon and air-pollutant emissions with lower-emission, affordable alternatives.