Comparison of Real-Time PM2.5 Between Rural and Urban Homes in Southwest China Based on Field Measurement: Insight Into the Cooking Activity Contribution

People generally spend most of their time indoors; thus, household air pollution (HAP), especially indoor air pollution, is of paramount importance. In this study, real-time particulate matter (PM_2.5) monitors were used to collect high temporal resolution concentrations of fine PM_2.5 in different microenvironments from 104 urban and rural households in Guizhou Province to investigate the urban–rural difference in HAP and the contribution of cooking activity to HAP. Results showed that PM_2.5 concentrations among different rural microenvironments varied largely, ranging from 26.10 ± 33.27 (mean ± standard deviation) in the bedroom to 69.20 ± 72.50 μg/m³ in the kitchen while varying slightly across various urban microenvironments, ranging from 32.30 ± 17.5 in the living room to 34.65 ± 16.37 μg/m³ in the kitchen. Cooking activity can rapidly increase PM_2.5 concentrations in the kitchen, whose peaks were at least five times higher than baseline levels. The contribution of cooking to the kitchen PM_2.5 was 18.43 ± 12.17% and 5.39 ± 4.15% in rural and urban homes, respectively. Biomass burning affected indoor PM_2.5 concentrations significantly, where rural households using biomass had the highest PM_2.5 levels than households burning other fuels. This study identified the urban–rural disparities in household PM_2.5 pollution and the contributions of cooking activities to HAP, illustrating the importance of cooking activities to indoor air pollution, which can assist in controlling indoor air pollution.