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Effect of Ventilation Systems and Air Filters on Decay Rates of Particles by Indoor Sources in an Occupied Townhouse



Cynthia H. Reed, L A. Wallace, Steven Emmerich


Several studies have shown the importance of particle losses in real homes due to deposition; however, none have shown the impact of using a central forced air fan and in-duct filter on particle deposition rates. In an attempt to provide such data, this study measured the deposition of fine and coarse particles following specific source events in an occupied townhouse. These tests resulted in a database of deposition rates for particles ranging from 0.3 mm to 10 mm under a wide range of realistic occupied house conditions. Deposition results were compared based on particle size, particle source, level of furnishings, operation of the heating and air conditioning (HAC) system both with and without a filter present, and different types of in-duct air cleaners. Of these factors, particle size, HAC fan operation, and air cleaner usage were found to have the most significant effect on particle deposition rates. With the central fan off, deposition rates varied from 0.3 h-1 for the smallest particle range (0.3 mm to 0.5 mm) to 5.2 h-1 for particles greater than 10 mm. Use of the central fan approximately doubled these rates for particles < 5 mm, and increased rates by 2 h-1 for the larger particles. The in-duct electrostatic precipitator increased the rates compared to the fan-off condition by factors of 5 to 10 for particles < 2.5 mm, and by a factor of 3 for the larger particles.
Atmospheric Environment
No. 38


coarse particles, deposition, filtration, fine particles, residential indoor air quality


Reed, C. , Wallace, L. and Emmerich, S. (2003), Effect of Ventilation Systems and Air Filters on Decay Rates of Particles by Indoor Sources in an Occupied Townhouse, Atmospheric Environment, [online], (Accessed July 22, 2024)


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Created November 30, 2003, Updated October 12, 2021