AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
A Method to Rapidly Measure Size-Resolved Particle Penetration Factors in Residences
HAORAN ZHAO, Brent Stephens, Illinois Institute of Technology
Abstract Number: 323 Working Group: Indoor Aerosols
Abstract Human exposure to particles of outdoor origin is dependent on their infiltration into buildings. In order to improve our knowledge of particle infiltration inside a wide variety of residences where people spend most of their time, methods to more rapidly measure particle penetration factors are required. Therefore, we refined existing test methods into a new method to measure size-resolved envelope penetration factors and applied it in an unoccupied apartment unit in Chicago, IL. The test procedure involves the following steps to yield estimates of both penetration factors (P) and deposition loss rate coefficients (k): (1) introduce outdoor particles through temporary increases in natural ventilation to elevate indoor particle concentrations, (2) measure the subsequent decay of indoor particles during a 30-60 minute indoor-only measurement period, and (3) alternately measure indoor and outdoor particle concentrations during normal infiltration conditions over a period of ~2 hours. An automatic switching system was used with a TSI NanoScan SMPS and Optical Particle Sizer to demonstrate the utility of this method. Estimates of P and k were made for 18 particle size ranges from 0.01 µm to 2.5 µm using multiple mathematical solutions to a time-varying mass balance on indoor particles of outdoor origin. Repeated measurements were made and results were explored to evaluate the accuracy and repeatability of the test procedure and solution methods. Preliminary results demonstrate that mean estimates of P ranged from 0.39±0.07 to 0.79±0.17 across the range of particle sizes, while estimates of k ranged from 0.53±0.02 to 1.65±0.15 hr-1. Additionally, these data were aggregated to provide estimates of P and k for ultrafine particles and PM2.5 mass (assuming spherical shape and unit density). This work provides a test method that minimizes the duration of testing without sacrificing accuracy for further application in field measurements.