AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Application of High Efficiency Cabin Air Filter for Simultaneous Control of Ultrafine Particles and Carbon Dioxide in Passenger Vehicles
EON LEE, Cha-Chen Fung, Yifang Zhu, University of California, Los Angeles
Abstract Number: 190 Working Group: Indoor Aerosols
Abstract Modern passenger vehicles are commonly equipped with cabin air filters, but the filtration efficiency is only at 40-60% for ultrafine particles (UFPs). Although setting the vehicle ventilation system to recirculation (RC) mode can reduce in-cabin UFPs by 80-95%, carbon dioxide (CO$_2) from exhaled breath of passengers can build up quickly inside the cabin. To avoid the CO$_2 build-up issue, the vehicle needs to be operated under outdoor air (OA) mode to allow sufficient air exchange. This study investigated in-cabin UFP removal under OA mode using high efficiency particulate air (HEPA) filters. UFP concentrations were simultaneously monitored inside and outside of 12 different vehicles under three different driving conditions: stationary, local roadway, and freeway. Under each experimental condition, data were collected with no filter, in-use original equipment manufacturer (OEM) filter, and two types of HEPA filters. The HEPA filters were found to reduce in-cabin UFP number concentration by 93% on average, much higher than in-use OEM filters (i.e., 41-65% on average). Using the HEPA filters also made the in-cabin environment more independent from the changes of driving speed and the fluctuation of UFP concentrations on different roadways. Throughout the measurements the in-cabin CO$_2 concentration remained at 626-816 ppm, a significant reduction from a typical in-cabin CO$_2 concentration range of 2500-4000 ppm in recirculation mode.