Development of a semi-mechanistic allergenic pollen emission model

Ting Cai, Yong Zhang, Xiang Ren, Leonard Bielory, Zhongyuan Mi, Christopher G. Nolte, Yang Gao, L. Ruby Leung, Panos G. Georgopoulos

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Modeling pollen emission processes is crucial for studying the spatiotemporal distributions of airborne allergenic pollen. A semi-mechanistic emission model was developed based on mass balance of pollen grain fluxes in the surroundings of allergenic plants. The emission model considers direct emission and resuspension and accounts for influences of temperature, wind velocity, and relative humidity. Modules of this emission model have been developed and parameterized with multiple years of pollen count observations to provide pollen season onset and duration, hourly flowering likelihood, and vegetation coverage for oak and ragweed, as two examples. The simulated spatiotemporal pattern of pollen emissions generally follows the corresponding pattern of area coverage of allergenic plants and diurnal pattern of hourly flowering likelihood. It is found that oak pollen emissions start from the Southern part of the Contiguous United States (CONUS) in March and then shift gradually toward the Northern CONUS, with a maximum emission flux of 5.8 × 10 6 pollen/(m 2 h). On the other hand, ragweed pollen emissions start from the Northern CONUS in August and then shift gradually toward the Southern CONUS. The mean ragweed emission flux during August to September can increase up to 2.4 × 10 6 pollen/(m 2 h). This emission model is robust with respect to the input parameters for oak and ragweed. Qualitative evaluations of the model performance indicated that the simulated pollen emission is strongly correlated with the plant coverages and observed pollen counts. This model could also be applied to other pollen species given the relevant parameters.

Original languageEnglish (US)
Pages (from-to)947-957
Number of pages11
JournalScience of the Total Environment
StatePublished - Feb 25 2019

All Science Journal Classification (ASJC) codes

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution


  • Allergy
  • Distribution
  • Emission
  • Model
  • Pollen
  • Sensitivity analysis


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