摘要：The purpose of this study was to evaluate outdoor PM<sub>2.5</sub> infiltration into multifamily homes according to the building characteristics using regression models. Field test results from 23 multifamily homes were analyzed to investigate the infiltration factor and building characteristics including floor area, volume, outer surface area, building age, and airtightness. Correlation and regression analysis were then conducted to identify the building factor that is most strongly associated with the infiltration of outdoor PM<sub>2.5</sub>. The field tests revealed that the average PM<sub>2.5</sub> infiltration factor was 0.71 (±0.19). The correlation analysis of the building characteristics and PM<sub>2.5</sub> infiltration factor revealed that building airtightness metrics (ACH<sub>50</sub>, ELA/FA, and NL) had a statistically significant (<i>p</i> < 0.05) positive correlation (<i>r</i> = 0.70, 0.69, and 0.68, respectively) with the infiltration factor. Following the correlation analysis, a regression model for predicting PM<sub>2.5</sub> infiltration based on the ACH<sub>50</sub> airtightness index was proposed. The study confirmed that the outdoor-origin PM<sub>2.5</sub> concentration in sufficiently leaky units could be up to 1.59 times higher than that in airtight units.
