title: Assessment of the capacity of vehicle cabin air inlet filters to reduce diesel exhaust-induced symptoms in human volunteers.
abstract: BACKGROUND
  Exposure to particulate matter (PM) air pollution especially derived from traffic is associated with increases in cardiorespiratory morbidity and mortality. In this study, we evaluated the ability of novel vehicle cabin air inlet filters to reduce diesel exhaust (DE)-induced symptoms and markers of inflammation in human subjects.
  
  
  METHODS
  Thirty healthy subjects participated in a randomized double-blind controlled crossover study where they were exposed to filtered air, unfiltered DE and DE filtered through two selected particle filters, one with and one without active charcoal. Exposures lasted for one hour. Symptoms were assessed before and during exposures and lung function was measured before and after each exposure, with inflammation assessed in peripheral blood five hours after exposures. In parallel, PM were collected from unfiltered and filtered DE and assessed for their capacity to drive damaging oxidation reactions in a cell-free model, or promote inflammation in A549 cells.
  
  
  RESULTS
  The standard particle filter employed in this study reduced PM10 mass concentrations within the exposure chamber by 46%, further reduced to 74% by the inclusion of an active charcoal component. In addition use of the active charcoal filter was associated by a 75% and 50% reduction in NO2 and hydrocarbon concentrations, respectively. As expected, subjects reported more subjective symptoms after exposure to unfiltered DE compared to filtered air, which was significantly reduced by the filter with an active charcoal component. There were no significant changes in lung function after exposures. Similarly diesel exhaust did not elicit significant increases in any of the inflammatory markers examined in the peripheral blood samples 5 hour post-exposure. Whilst the filters reduced chamber particle concentrations, the oxidative activity of the particles themselves, did not change following filtration with either filter. In contrast, diesel exhaust PM passed through the active charcoal combination filter appeared less inflammatory to A549 cells.
  
  
  CONCLUSIONS
  A cabin air inlet particle filter including an active charcoal component was highly effective in reducing both DE particulate and gaseous components, with reduced exhaust-induced symptoms in healthy volunteers. These data demonstrate the effectiveness of cabin filters to protect subjects travelling in vehicles from diesel exhaust emissions.
authors.forename: Ala
authors.initials: A
authors.lastname: Muala
authors.forename: Maria
authors.initials: M
authors.lastname: Sehlstedt
authors.forename: Anne
authors.initials: A
authors.lastname: Bion
authors.forename: Camilla
authors.initials: C
authors.lastname: Osterlund
authors.forename: Jenny A
authors.initials: JA
authors.lastname: Bosson
authors.forename: Annelie F
authors.initials: AF
authors.lastname: Behndig
authors.forename: Jamshid
authors.initials: J
authors.lastname: Pourazar
authors.forename: Anders
authors.initials: A
authors.lastname: Bucht
authors.forename: Christoffer
authors.initials: C
authors.lastname: Boman
authors.forename: Ian S
authors.initials: IS
authors.lastname: Mudway
authors.forename: Jeremy P
authors.initials: JP
authors.lastname: Langrish
authors.forename: Stephane
authors.initials: S
authors.lastname: Couderc
authors.forename: Anders
authors.initials: A
authors.lastname: Blomberg
authors.affiliation: Department of Public Health and Clinical Medicine, Division of Medicine, Umeå University, Umeå, Sweden. thomas.sandstrom@lung.umu.se.
authors.forename: Thomas
authors.initials: T
authors.lastname: Sandström
mesh_terms: D000293:Adolescent; D000328:Adult; D061808:Air Filters; D000393:Air Pollutants / Q000032:analysis / Q000633:toxicity*; D000397:Air Pollution / Q000009:adverse effects / Q000032:analysis / Q000517:prevention & control*; D045744:Cell Line, Tumor; D002606:Charcoal; D018592:Cross-Over Studies; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D006838:Hydrocarbons / Q000032:analysis / Q000633:toxicity; D016209:Interleukin-8 / Q000276:immunology; D007509:Irritants / Q000032:analysis / Q000633:toxicity*; D008297:Male; D018986:Motor Vehicles; D009569:Nitric Oxide / Q000032:analysis / Q000633:toxicity; D009585:Nitrogen Dioxide / Q000032:analysis / Q000633:toxicity; D009812:Odorants; D052638:Particulate Matter / Q000032:analysis / Q000633:toxicity; D012129:Respiratory Function Tests; D013649:Taste; D001335:Vehicle Emissions / Q000032:analysis / Q000633:toxicity*; D055815:Young Adult
chemical_list: D000393:Air Pollutants; D006838:Hydrocarbons; D016209:Interleukin-8; D007509:Irritants; D052638:Particulate Matter; D001335:Vehicle Emissions; D002606:Charcoal; D009569:Nitric Oxide; D009585:Nitrogen Dioxide