02151nas a2200265   4500000000100000000000100001008004100002100001900043700002100062700001500083700001700098700002700115700001500142700002700157700001700184700002500201700002500226700001800251700002000269245009200289856004600381490000700427520143700434022001401871       2023                            d1 aBujin Bekbulat1 aPratyush Agrawal1 aRyan Allen1 aMichael Baum1 aBuyantushig Boldbaatar1 aLara Clark1 aJargalsaikhan Galsuren1 aPerry Hystad1 aChristian L’Orange1 aSreekanth Vakacherla1 aJohn Volckens1 aJulian Marshall00aApplication of an Ultra-Low-Cost Passive Sampler for Light-Absorbing Carbon in Mongolia  uhttps://www.mdpi.com/1424-8220/23/21/89770 v233 aLow-cost, long-term measures of air pollution concentrations are often needed for epidemiological studies and policy analyses of household air pollution. The Washington passive sampler (WPS), an ultra-low-cost method for measuring the long-term average levels of light-absorbing carbon (LAC) air pollution, uses digital images to measure the changes in the reflectance of a passively exposed paper filter. A prior publication on WPS reported high precision and reproducibility. Here, we deployed three methods to each of 10 households in Ulaanbaatar, Mongolia: one PurpleAir for PM2.5; two ultrasonic personal aerosol samplers (UPAS) with quartz filters for the thermal-optical analysis of elemental carbon (EC); and two WPS for LAC. We compared multiple rounds of 4-week-average measurements. The analyses calibrating the LAC to the elemental carbon measurement suggest that 1 µg of EC/m3 corresponds to 62 PI/month (R2 = 0.83). The EC-LAC calibration curve indicates an accuracy (root-mean-square error) of 3.1 µg of EC/m3, or ~21% of the average elemental carbon concentration. The RMSE values observed here for the WPS are comparable to the reported accuracy levels for other methods, including reference methods. Based on the precision and accuracy results shown here, as well as the increased simplicity of deployment, the WPS may merit further consideration for studying air quality in homes that use solid fuels.  a1424-8220