Natural Ventilation Reduces Cooking-Related PM_2.5 Peaks Indoors

Indoor cooking generates intense, short-duration fine particulate matter (PM_2.5) peaks with acute health risks. To quantify the efficacy of natural ventilation configurations, we conducted approximately two months of continuous monitoring in a modern UK one-bedroom apartment, comparing three ventilation scenarios during cooking: fully opened (all windows and internal doors open), door-opened only (internal doors open but windows closed), and fully closed (all windows and internal doors closed). Air quality sensors were calibrated against a reference instrument (Fidas 200E) both before and after the field deployment. During the study period, outdoor PM_2.5 mass concentrations ranged from 0.4 to 31.0 μg m^-3, averaging 6.3 μg m^-3. Indoor concentrations were substantially higher than average outdoor levels, with the fully opened scenario yielding the lowest exposure at 14.9 μg m^-3 in the living room/kitchen and 15.4 μg m^-3 in the bedroom. Relative to the fully opened scenario, PM_2.5 concentrations increased by 58.4% (living room/kitchen) and 55.8% (bedroom) under door-opened only conditions, and under fully closed conditions by 28.9% and 27.9%, respectively. These findings demonstrate that simultaneous opening of windows and internal doors during cooking can substantially reduce acute PM_2.5 exposure, offering a simple, low-energy strategy to mitigate short-term health risks in naturally ventilated apartments.