title: Method for a homogeneous distribution of pollens in an environmental exposure chamber.
abstract: A variety of different environmental exposure chambers (EECs) have been used to evaluate treatments for allergic rhinitis.
  
  
  
  To describe and test a system for a homogenous distribution of grass pollen, Phleum Pratense, in an EEC to be used for controlled pollen exposure studies in allergic participants.
  
  
  
  A chamber made of stainless steel with completely rounded corners, seating four individuals at a time, was used. Room pressure, temperature, humidity and the air change rate were kept constant throughout the study period. A rotating pipette dispensed a uniform supply of pollen into a turntable's v-shaped grooves. A stainless steel capillary tube sucked the pollens into a venturi throat at which time the pollens were mixed with a high-pressure airstream of compressed high-efficiency particulate arrestance filtered air and then transported to a spreading plate inside the EEC. To achieve uniform concentrations in the EEC, the turntable's rotating speed was continuously adjusted using information from video-coupled feedback and feed forward mechanisms. Pollen levels were detected using standard volumetric air samplers and laser particle counters. The target pollen exposure level was 1000 pollens/m(3) . Twenty-one participants were exposed to pollens in the EEC twice for 210 min. Participants evaluated their symptoms every 30 min using a total nasal symptom score (TNSS) consisting of blocked nose, runny nose, nasal itching and sneezing.
  
  
  
  Across fifteen study days, the average pollen level was 982 pollens/m(3) (SD, 102 pollens/m(3) ). On average, participants experienced a 10% difference in overall pollen levels between their two visits to the EEC. The mean TNSSs rose throughout the exposure period, with a low at baseline of 0.43 (SD, 0.68) to a high of 4.71 (SD, 2.43) just before exiting the EEC.
  
  
  
  This EEC provides a reproducible, precise and homogenous distribution of pollens making it suitable for single-centre allergy clinical trials.
authors.affiliation: Department of Public Health, Section for Environment, Occupation and Health, Aarhus University, Aarhus, Denmark.|Rhinix ApS, Aarhus, Denmark.
authors.forename: P
authors.initials: P
authors.lastname: Kenney
authors.affiliation: Department of Public Health, Section for Environment, Occupation and Health, Aarhus University, Aarhus, Denmark.
authors.forename: J
authors.initials: J
authors.lastname: Bønløkke
authors.affiliation: Department of Respiratory Diseases and Allergology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: O
authors.initials: O
authors.lastname: Hilberg
authors.affiliation: Department of Public Health, Section for Environment, Occupation and Health, Aarhus University, Aarhus, Denmark.
authors.forename: P
authors.initials: P
authors.lastname: Ravn
authors.affiliation: Department of Public Health, Section for Environment, Occupation and Health, Aarhus University, Aarhus, Denmark.|National Research Center for the Working Environment, Copenhagen, Denmark.
authors.forename: V
authors.initials: V
authors.lastname: Schlünssen
authors.affiliation: Department of Public Health, Section for Environment, Occupation and Health, Aarhus University, Aarhus, Denmark.
authors.forename: T
authors.initials: T
authors.lastname: Sigsgaard
mesh_terms: D000328:Adult; D000485:Allergens / Q000276:immunology*; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology; D008297:Male; D011058:Pollen / Q000276:immunology*; D065631:Rhinitis, Allergic / Q000175:diagnosis / Q000188:drug therapy / Q000276:immunology / Q000378:metabolism; D012720:Severity of Illness Index; D063189:Symptom Assessment
chemical_list: D000485:Allergens; D007073:Immunoglobulin E
keywords: Allergen exposure chamber; Allergic Rhinitis; Clinical trial; Controlled; Controlled allergen challenge; Environmental Exposure Chamber; Pollen exposure; grass pollen