Indoor atmospheric nanoparticle emissions, inhalation exposures, and indoor-to-outdoor transport during residential activities with electric and combustion appliances

Indoor-originated nanoparticles are an emerging class of hazardous airborne contaminants with the capacity to penetrate deep into the respiratory system and translocate to sensitive organs. Use of electric appliances is widely promoted to improve indoor and outdoor air quality, yet their implications for nanoparticle emissions during residential cooking, particularly under oil-based high-temperature conditions, remain poorly understood. Using a controlled residential test house, we conducted the first size-resolved comparison of nanoparticles down to 1 nm emitted during full-day household activities performed exclusively with combustion- or electric-based appliances. High-temperature oil-based electric induction cooking generated peak nanoparticle concentrations on the order of 10 7 nanoparticles cm -3 , comparable to high-temperature oil-based gas stove cooking. Both produced abundant sub-3 nm nanocluster aerosol (NCA) that accounted for >80% of total counts during active emission periods. Across full-day activity cycles, electric and combustion appliances yielded similar cumulative nanoparticle emissions and inhalation exposures, with daily respiratory tract deposited doses reaching approximately 10 12 nanoparticles under both appliance scenarios. Furthermore, modeled indoor-to-outdoor nanoparticle fluxes were substantial for both appliance types (10 12 –10 13 nanoparticles min -1 ), and building-footprint-normalized fluxes from electric-appliance use (10 10 –10 11 nanoparticles m -2 min -1 ) exceeded reported urban traffic nanoparticle fluxes. These findings demonstrate that non-combustion, thermally driven processes can generate intense bursts of indoor atmospheric nanoparticles and NCA, challenging the assumption that residential electrification universally reduces nanoparticle pollution. Effective mitigation strategies must therefore address primary and secondary nanoparticle sources in residential environments and the size-dependent exposure and indoor-to-outdoor transport processes revealed here. • Electric induction and gas stove cooking both generate ~10 7 nanoparticles cm -3 . • Sub-3 nm nanocluster aerosol is abundant during high-temperature oil-based cooking. • Daily inhalation dose reaches ~10 12 nanoparticles under electric and combustion use. • Indoor-to-outdoor nanoparticle fluxes rival or exceed urban traffic emissions. • Building electrification alone is unlikely to reduce indoor nanoparticle pollution.