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Infiltration of Outdoor Ultrafine Particles into a Test House



Dong H. Rim, Lance L. Wallace, Andrew K. Persily


Ultrafine particles (UFP) have been related to adverse human health effects such as respiratory and cardiovascular mortality. However, human exposure to particles of outdoor origin is heavily dependent on their infiltration into homes, where most people spend most of their time. The infiltration factor (Finf) becomes of enormous importance in epidemiological studies. The objective of this study is to investigate the transport of UFP into a residential building and to determine the functional dependence of infiltration on particle size and air change rate. Using continuous measurements of indoor and outdoor concentrations of size-resolved particles ranging from 2 nm to 100 nm in a manufactured test house, particle penetration through the building, deposition to indoor surfaces, and the resulting value of Finf were calculated. Finf increases with particle diameter and with increasing air change rate. These two factors alone account for about 80% of the observed variance. Finf ranges from close to 0 (particles < 10 nm) to 0.3 (particles > 80 nm) with windows closed and from 0 to 0.6 with one window open about 7.5 cm. Infiltration of UFP is lower than for PM2.5 (<2.5µm), implying that indoor-generated sources are relatively more important for UFP than for PM2.5.
Environmental Science & Technology


ultrafine particles, infiltration, deposition, penetration, dynamic modeling


Rim, D. , Wallace, L. and Persily, A. (2010), Infiltration of Outdoor Ultrafine Particles into a Test House, Environmental Science & Technology, [online], (Accessed April 23, 2024)
Created August 1, 2010, Updated October 12, 2021