International Journal of Biometeorology

, Volume 58, Issue 6, pp 1317–1325 | Cite as

Do urban canyons influence street level grass pollen concentrations?

  • Robert George Peel
  • Roy Kennedy
  • Matt Smith
  • Ole Hertel
Original Paper


In epidemiological studies, outdoor exposure to pollen is typically estimated using rooftop monitoring station data, whilst exposure overwhelmingly occurs at street level. In this study the relationship between street level and roof level grass pollen concentrations was investigated for city centre street canyon environments in Aarhus, Denmark, and London, UK, during the grass pollen seasons of 2010 and 2011 respectively. For the period mid-day to late evening, street level concentrations in both cities tended to be lower than roof-level concentrations, though this difference was found to be statistically significant only in London. The ratio of street/roof level concentrations was compared with temperature, relative humidity, wind speed and direction, and solar radiation. Results indicated that the concentration ratio responds to wind direction with respect to relative canyon orientation and local source distribution. In the London study, an increase in relative humidity was linked to a significant decrease in street/roof level concentration ratio, and a possible causative mechanism involving moisture mediated pollen grain buoyancy is proposed. Relationships with the other weather variables were not found to be significant in either location. These results suggest a tendency for monitoring station data to overestimate exposure in the canyon environment.


Monitoring Station Pollen Concentration Street Canyon Grass Pollen Street Level 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



The first author would like to extend special thanks to Stine Rødjajn for help with sample collection, to Janne Sommer at Astma-Allergi Danmark for providing access to data and facilities, and to Dr. Harry Morrow Brown for generously lending equipment. The Danish Air Quality Monitoring Programme, and in particular Thomas Ellermann, are also thanked for contributing meteorological data.


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Copyright information

© ISB 2013

Authors and Affiliations

  • Robert George Peel
    • 1
    • 2
  • Roy Kennedy
    • 2
  • Matt Smith
    • 2
  • Ole Hertel
    • 1
    • 3
  1. 1.Department of Environmental ScienceAarhus UniversityRoskildeDenmark
  2. 2.National Pollen and Aerobiology Research UnitUniversity of WorcesterWorcesterUK
  3. 3.Department for Environmental, Social and Spatial Change (ENSPAC)Roskilde UniversityRoskildeDenmark

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