Estimation of Nitrogen Dioxide Source Generation and Ventilation Rate in Residence Using Multiple Measurements in Korea

Indoor air quality can be affected by indoor sources, ventilation, decay and outdoor levels. Alt hough technologies exist to measure these factors, direct measurements are often difficult. The purpose of this study was to develop an alternative method to characterize indoor environmental factors by multiple indoor and outdoor measurements. Daily indoor and outdoor NO2 concentrations were measured for 30 consecutive days in 28 houses in Brisbane, Australia, and for 21 consecutive days in 37 houses in Seoul, Korea. Using a mass balance model and regression analysis, penetration factor (ventilation rate divided by the sum of ventilation rate and deposition constant) and source strength factor (source strength divided by the sum of ventilation rate and deposition constant) were calculated using multiple indoor and outdoor measurements. Subsequently, the ventilation rate and NO2 source strength were estimated. Geometric means of ventilation rate were 1.44 ACH in Brisbane, assuming a residential NO2 deposition constant of 1.05 hr-1, and 1.36 ACH in Seoul, with the measured residential NO2 deposition constant of 0.94 hr-1. Source strengths of N02 were 15.8 ${\pm}$ 18.2 ${\mu}$g/m3${\cdot}$hr and 44.7 ${\pm}$ 38.1 ${\mu}$g/m3${\cdot}$hr in Brisbane and Seoul, respectively. In conclusion, indoor environmental factors were effectively characterized by this method using multiple indoor and outdoor measurements.