title: Laboratory and on-road evaluations of cabin air filters using number and surface area concentration monitors.
abstract: An automotive cabin air filter's effectiveness for removing airborne particles was determined both in a laboratory wind tunnel and in vehicle on-road tests. The most penetrating particle size for the test filter was approximately 350 nm, where the filtration efficiency was 22.9 and 17.4% at medium and high fan speeds, respectively. The filtration efficiency increased for smaller particles and was 43.9% for 100 nm and 72.0% for 20 nm particles at a medium fan speed. We determined the reduction in passenger exposure to particles while driving in freeway traffic caused by a vehicle ventilation system with a cabin air filter installed. Both particle number and surface area concentration measurements were made inside the cabin and in the surrounding air. At medium fan speed, the number and surface area concentration-based exposure reductions were 65.6 +/- 6.0% and 60.6 +/- 9.4%, respectively. To distinguish the exposure reduction contribution from the filter alone and the remainder of the ventilation system, we also performed tests with and without the filter in place using the surface area monitors. The ventilation system operating in the recirculation mode with the cabin air filter installed provided the maximum protection, reducing the cabin particle concentration exponentially over time and usually taking only 3 min to reach 10 microm2/cm3 (a typical office air condition) under medium fan speed.
authors.affiliation: Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA. chaolong@me.umn.edu
authors.forename: Chaolong
authors.initials: C
authors.lastname: Qi
authors.forename: Nick
authors.initials: N
authors.lastname: Stanley
authors.forename: David Y H
authors.initials: DY
authors.lastname: Pui
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Kuehn
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D004781:Environmental Exposure / Q000517:prevention & control*; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods; D005374:Filtration / Q000295:instrumentation; D007753:Laboratories; D018986:Motor Vehicles; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D014691:Ventilation / Q000295:instrumentation* / Q000379:methods
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter