Particle Diffusion and Resident Satisfaction with External Fire Kangs for Winter Heating in Northwest Arid Rural China: A Case Study in Baoji

In the context of rural construction, studying particle diffusion alongside residents’ satisfaction with rural external heated kangs provides important support for upgrading heating facilities and improving domestic infrastructure in the northwest arid regions of China. This study takes a single rural household equipped with an external fire kang in Baoji as the research object. From the perspectives of operational and service management in human settlements, the spatio-temporal diffusion characteristics of particulate matter in the outdoor combustion port, living room, and bedroom during the winter heating period are continuously monitored, and data on resident satisfaction are collected through a questionnaire. The results show that, during the external kang’s heating period, the spatial concentrations of particulate matter decrease in the following order: combustion port > living room > bedroom. Concentrated morning and evening kang heating creates a typical bimodal distribution of outdoor particulate matter concentration, with peaks at 8:00 am and 8:00 pm. During the ignition period, coarse particles (PM10) are mostly released, while the proportion of fine particles (PM2.5, PM1.0) increases during the stable combustion period. During the sealing period, the concentration of fine particles doubles. After extinguishing, PM10 decays rapidly due to gravity deposition, while PM1.0 shows a longer environmental retention time due to its slow diffusion. The core diffusion process of the particulate matter mainly occurs within a distance of 5–15 m from the combustion port. The resident satisfaction survey shows moderate comprehensive satisfaction with external heated kangs, at 3.10 points on a 5-point scale. Addressing existing problems and proposing relevant strategies, this study provides a theoretical basis and technical support for the rational transformation of external heated kangs in the arid areas of Northwest China.