Background; - PM2.5 is an indicator of household air pollutants to measure the risk of air pollution.rnUPAS and PATS+ PM measuring instruments are portable monitors that were used to measurernparticulate matters in the households of Addis Ababa in a GEO Health for Eastern Africa. Thernvalidity of the measurements using these two instruments is a concern for exposure assessment asrnthey use different principles of measuring PM2.5.rnObjective: This study aims to validating PM2.5 concentrations measured by PATS+ relative tornUPAS device in households in Addis Ababa and explore factors affecting the level of UPAS PM2.5rnconcentration.rnMethods: The study was cross-sectional, involving 150 households. The study used tworninstruments with different technologies: the light scattering method in PATS+ and the gravimetricrnin UPAS. Fifteen households were randomly selected from each sub-city from the sourcernpopulation that it used GEO Health project for Children’s Health Study. Different statistical toolsrnwere used to explore the consistency and validity of the measured PM2.5 by the two tools used tornmonitor for 24 hours for each household: paired t-test, and Bland-Altman scatter plot analysis werernperformed to evaluate the extent of agreement. P-Value