BC concentrations were measured by a Model AE51 microAeth Black Carbon aerosol monitor (Aethlabs, Inc., range: 0e1 mg/m3, resolution: 0.001 mg/m3) at 50 mL/min flow rate. Due to the high concentrations of BC in the residences, the filter was changed every 2e4 h. The battery was recharged overnight every day. PM2.5 concentrations were measured with a Model 8520 DustTrak aerosol monitor (TSI, range: 0.01e100 mg/m3, resolution: 0.1% of reading or 0.001 mg/m3) at 1.7 L/min flowrate. Two sets of batteries were used and recharged every day and the PM2.5 instrument was left operating overnight in residents' homes. Operation temperatures for the BC and PM2.5 monitors are 0e40 C and 0e50 C, respectively. Because of occasional battery failure due to cold, and the need to change filters every 2e4 h while respecting residents’ privacy, it was not possible to monitor BC for 24 h, but four overnight PM2.5 datasets were successfully collected in this study. The instruments were calibrated once before starting measurements.