Mass loading of particles in the supply ducts of mechanical ventilation systems in homes

The objective of this study was to measure the mass and number loading of particles in supply ducts of homes with different mechanical fan operation conditions. Fifteen occupied single-family homes were selected from three multi-family residential complexes located in suburban areas of Seoul. The sample homes have mechanical ventilation systems that operate independently of heating and cooling devices. Field measurements consisted of three parts: a questionnaire regarding the indoor environment and occupant behavior related to ventilation; measurements of size resolved particle concentrations before and after operating the mechanical fan; an inspection of the proper installation of a filter unit and airflow in the supply ducts. The PM10 mass loading in the supply ducts ranged from 13.0 to 450 mg/m2. The mass and number loading of particles in the supply ducts increased exponentially according to the built year of homes. The averaged PM10 loadings for two, five, and seven years after built were 11.6, 39.0, and 114.8 mg/m2, respectively. Most of the occupants, 10 of 15 (67%), did not use mechanical fans to ventilate their homes, and the operation time of the mechanical fan significantly influenced on the particle loading rate in the supply ducts.