Infiltration of Outdoor Ultrafine Particles into a Test House Donghyun Rim Lance Wallace Andrew Persily Indoor Air Quality and Ventilation Group, Energy and Environment Division Engineering Laboratory, National Institute of Standards and Technology 100 Bureau Drive Gaithersburg, MD 20899 Content submitted to and published by: Environmental Science and Technology 2010; Volume 44: 5908-5913 U.S. Department of Commerce Dr. Rebecca M. Blank, Acting Secretary National Institute of Standards and Technology Patrick D. Gallagher, Director