The exposure of children to air pollution in low resource settings is believed to be high because of the common use of biomass fuels for cooking. We used microenvironment sampling to estimate the respirable fraction of air pollution (particles with median diameter less than 4μm) to which 7–9year old children in southern Nepal were exposed. Sampling was conducted for a total 2649h in 55 households, 8 schools and 8 outdoor locations of rural Dhanusha. We conducted gravimetric and photometric sampling in a subsample of the children in our study in the locations in which they usually resided (bedroom/living room, kitchen, veranda, in school and outdoors), repeated three times over one year. Using time activity information, a 24-hour time weighted average was modeled for all the children in the study. Approximately two-thirds of homes used biomass fuels, with the remainder mostly using gas. The exposure of children to air pollution was very high. The 24-hour time weighted average over the whole year was 168μg/m3. The non-kitchen related samples tended to show approximately double the concentration in winter than spring/autumn, and four times that of the monsoon season. There was no difference between the exposure of boys and girls. Air pollution in rural households was much higher than the World Health Organization and the National Ambient Air Quality Standards for Nepal recommendations for particulate exposure. •Air pollution exposure (respirable PM) was estimated for children in Nepal.•Gravimetric and photometric microenvironment sampling was conducted.•Total sampling was repeated three times over a year and totaled over 2500 hours.•The 24-hour time weighted average was 168µg/m3.•There was substantial variability from season to season and by fuel type.•There was no difference in exposure between boys and girls.