title: An investigation of airborne allergenic pollen at different heights.
abstract: OBJECTIVE
  Airborne pollen is an important source of allergens in a number of allergic diseases. Data on the concentrations of pollen at different heights in the air are scarce. The aim of the present study was to investigate different types and numbers of airborne pollen and their seasonal variation at different heights in the urban area of Shenzhen (China) and their associations with meteorological factors.
  
  
  METHODS
  The concentration of airborne pollen at different heights was monitored with Burkard traps from July 1, 2006, to June 30, 2007, in Shenzhen; the results were analyzed with SAS 9.13 software.
  
  
  RESULTS
  In total, 1,095 films (at 3 heights, 365 films at each height) were exposed throughout the year, and 48 families and 85 genera of pollen taxa were identified. The total pollen count was 55,830 grains (25,204 grains at 1.5 m; 16,218 grains at 35 m, and 14,408 grains at 70 m); pollen grains were present in the atmosphere throughout the year, with two peaks of airborne pollen: one peak in February to April and the other in September to November.
  
  
  CONCLUSIONS
  On the basis of our local investigations, the pollen concentrations and the pollen types in the air decrease gradually with increasing height. The distribution and concentrations of airborne pollen at different heights in the atmosphere were influenced by composite factors such as the season and meteorological factors.
authors.affiliation: Institute of Allergy and Immunology, Shenzhen University, Shenzhen, China.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Xiao
authors.forename: Aixiang
authors.initials: A
authors.lastname: Fu
authors.forename: Xiongjie
authors.initials: X
authors.lastname: Xie
authors.forename: Minxiong
authors.initials: M
authors.lastname: Kang
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Hu
authors.forename: Pingchang
authors.initials: P
authors.lastname: Yang
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Liu
mesh_terms: D000485:Allergens / Q000032:analysis*; D001272:Atmosphere / Q000737:chemistry*; D002681:China; D008685:Meteorological Concepts; D052638:Particulate Matter / Q000032:analysis*; D011058:Pollen; D012621:Seasons
chemical_list: D000485:Allergens; D052638:Particulate Matter