Exposure to PM2.5 is a leading environmental risk factor for many diseases and premature deaths, arousing growing public concerns. In this study, indoor and outdoor PM2.5 concentrations were investigated during the heating and non-heating seasons in an urban area in northwest China. Personal inhalation exposure levels among different age groups were evaluated, and the difference attributable to different cooking fuels including coal, gas and electricity, was discussed. The average concentrations of PM2.5 in the kitchen and the bedroom were 125±51 and 119±64μg/m3 during the heating season, and 80±67 and 80±50μg/m3 during the non-heating season, respectively. Indoor PM2.5, from indoor combustion sources but also outdoor penetration, contributed to about 75% of the total PM2.5 exposure. Much higher indoor concentrations and inhalation exposure levels were found in households using coal for cooking compared to those using gas and electricity. Changing from coal to gas or electricity for cooking could result in a reduction of PM2.5 in the kitchen by 40–70% and consequently lower inhalation exposure levels, especially for children and women. Display omitted •Comparison and seasonal differences in indoor and outdoor PM2.5•Estimate personal inhalation exposure and indoor/outdoor contributions•Distinct indoor PM2.5 levels attributable to different cooking fuels•Use of coal for cooking leads to higher indoor pollution and exposure level.•Indoor PM2.5 exposure contributed to near 75% of total inhalation exposure.