The article discusses preparations for indoor air sampling and mutagenicity studies of emissions from unvented coal combustion in homes in rural Xuan Wei County in southern China. A medium-volume sampler was developed to collect particles less than 10-micrometers and semivolatile organics, using a filter and XAD-2 resin, respectively. A high-volume particulate sampler was used for comparison. Coal was burned under conditions that simulated open-pit combustion that occurs in Xuan Wei. High- and medium-volume sampling yielded similar, high particulate concentrations of 38-39 mg/cu m. Of the total extractable organic mass, 15% was collected in the XAD-2 resin; the remaining 85% was retained in the filter. Polycyclic aromatic hydrocarbons found in the XAD consisted of four or fewer rings. The XAD sample showed low mutagenic activity, with most of the mutagenic activity found in the filter. Coal combustion emitted both direct- and indirect-acting mutagens, most of which were frameshift mutagens. (Copyright (c) 1987 American Chemical Society.)