title: Effect of cabin ventilation rate on ultrafine particle exposure inside automobiles.
abstract: We alternately measured on-road and in-vehicle ultrafine (<100 nm) particle (UFP) concentration for 5 passenger vehicles that comprised an age range of 18 years. A range of cabin ventilation settings were assessed during 301 trips through a 4 km road tunnel in Sydney, Australia. Outdoor air flow (ventilation) rates under these settings were quantified on open roads using tracer gas techniques. Significant variability in tunnel trip average median in-cabin/on-road (I/O) UFP ratios was observed (0.08 to approximately 1.0). Based on data spanning all test automobiles and ventilation settings, a positive linear relationship was found between outdoor air flow rate and I/O ratio, with the former accounting for a substantial proportion of variation in the latter (R(2) = 0.81). UFP concentrations recorded in-cabin during tunnel travel were significantly higher than those reported by comparable studies performed on open roadways. A simple mathematical model afforded the ability to predict tunnel trip average in-cabin UFP concentrations with good accuracy. Our data indicate that under certain conditions, in-cabin UFP exposures incurred during tunnel travel may contribute significantly to daily exposure. The UFP exposure of automobile occupants appears strongly related to their choice of ventilation setting and vehicle.
authors.affiliation: International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Australia. luke.knibb@qut.edu.au
authors.forename: Luke D
authors.initials: LD
authors.lastname: Knibbs
authors.forename: Richard J
authors.initials: RJ
authors.lastname: de Dear
authors.forename: Lidia
authors.initials: L
authors.lastname: Morawska
mesh_terms: D000392:Air Movements; D000393:Air Pollutants; D016902:Air Pollution, Indoor / Q000032:analysis*; D001315:Australia; D001336:Automobiles; D004781:Environmental Exposure; D004784:Environmental Monitoring / Q000379:methods; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D014691:Ventilation
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter