title: Side-by-side comparison of automatic pollen counters for use in pollen information systems.
abstract: BACKGROUND
  Recent effort to build an unmanned pollen monitoring network in Japan has led to new developments in automatic pollen counters. In-the-field performance tests of these automatic counters have not been reported.
  
  
  OBJECTIVE
  To characterize recently developed automatic pollen counters, with a view of using their data in pollen information systems.
  
  
  METHODS
  We performed side-by-side comparisons between 2 recently developed automatic pollen counters and 2 reference samplers at 2 sites during the 2005 pollen season.
  
  
  RESULTS
  Both automatic counters were found to have similar overall performance in terms of their correlations with the reference samplers. The linear correlation coefficient between the hourly values of the counters and one of the reference samplers was larger than 0.8 at both sites for both counters. Although these results are encouraging, our analysis also points to weaknesses of the investigated automatic counters in the areas of pollen discrimination, minimum measurable concentration, and calibration. Both counters were found to be affected by large concentrations of particulate matter, although the conditions and extent to which the particulate matter disrupted the measurements differ for the 2 sensors. The effect of particulate matter is particularly noticeable at the start and end of the pollen season, that is, when pollen concentration is low relative to particulate matter concentration. Further, it was found that one of the automatic counters could not differentiate snow particles from pollen grains.
  
  
  CONCLUSIONS
  The tested automatic pollen counters had good overall performances, but weaknesses in the areas of pollen discrimination, minimum measurable concentration, and calibration still have to be addressed for these counters to find widespread use in the allergy community.
authors.affiliation: Department of Mechanical Engineering, The University of Tokyo, School of Engineering, Tokyo, Japan. jean@mech.t.u-tokyo.ac.jp
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Delaunay
authors.forename: Hajime
authors.initials: H
authors.lastname: Sasajima
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Okamoto
authors.forename: Masahiko
authors.initials: M
authors.lastname: Yokota
mesh_terms: D004784:Environmental Monitoring / Q000295:instrumentation*; D052638:Particulate Matter / Q000032:analysis*; D011058:Pollen; D015203:Reproducibility of Results
chemical_list: D052638:Particulate Matter