Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 5.509 IF 5.509
  • IF 5-year value: 5.689 IF 5-year 5.689
  • CiteScore value: 5.44 CiteScore 5.44
  • SNIP value: 1.519 SNIP 1.519
  • SJR value: 3.032 SJR 3.032
  • IPP value: 5.37 IPP 5.37
  • h5-index value: 86 h5-index 86
  • Scimago H index value: 161 Scimago H index 161
Volume 17, issue 3 | Copyright
Atmos. Chem. Phys., 17, 2459-2475, 2017
https://doi.org/10.5194/acp-17-2459-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 16 Feb 2017

Research article | 16 Feb 2017

Influence of rain on the abundance of bioaerosols in fine and coarse particles

Chathurika M. Rathnayake1, Nervana Metwali2, Thilina Jayarathne1, Josh Kettler1, Yuefan Huang1, Peter S. Thorne2,3, Patrick T. O'Shaughnessy2,3, and Elizabeth A. Stone1 Chathurika M. Rathnayake et al.
  • 1Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA
  • 2Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA 52242, USA
  • 3Department of Civil and Environmental Engineering, University of Iowa, Iowa City, IA 52242, USA

Abstract. Assessing the environmental, health, and climate impacts of bioaerosols requires knowledge of their size and abundance. These two properties were assessed through daily measurements of chemical tracers for pollens (sucrose, fructose, and glucose), fungal spores (mannitol and glucans), and Gram-negative bacterial endotoxins in two particulate matter (PM) size modes: fine particles (<2.5µm) and coarse particles (2.5–10µm) as determined by their aerodynamic diameter. Measurements were made during the spring tree pollen season (mid-April to early May) and late summer ragweed season (late August to early September) in the Midwestern US in 2013. Under dry conditions, pollen, and fungal spore tracers were primarily in coarse PM (>75%), as expected for particles greater than 2.5µm. Rainfall on 2 May corresponded to maximum atmospheric pollen tracer levels and a redistribution of pollen tracers to the fine PM fraction (>80%). Both changes were attributed to the osmotic rupture of pollen grains that led to the suspension of fine-sized pollen fragments. Fungal spore tracers peaked in concentration following spring rain events and decreased in particle size, but to a lesser extent than pollens. A short, heavy thunderstorm in late summer corresponded to an increase in endotoxin and glucose levels, with a simultaneous shift to smaller particle sizes. Simultaneous increase in bioaerosol levels and decrease in their size have significant implications for population exposures to bioaerosols, particularly during rain events. Chemical mass balance (CMB) source apportionment modeling and regionally specific pollen profiles were used to apportion PM mass to pollens and fungal spores. Springtime pollen contributions to the mass of particles <10µm (PM10) ranged from 0.04 to 0.8µgm−3 (0.2–38%, averaging 4%), with maxima occurring on rainy days. Fungal spore contributions to PM10 mass ranged from 0.1 to 1.5µgm−3 (0.8–17%, averaging 5%), with maxima occurring after rain. Overall, this study defines changes to the fine- and coarse-mode distribution of PM, pollens, fungal spores, and endotoxins in response to rain in the Midwestern United States and advances the ability to apportion PM mass to pollens.

Download & links
Publications Copernicus
Download
Short summary
Exposures to bioaerosols depend on their type, particle size, and concentration. While typically found in coarse particles (2.5–10 microns), pollens, fungal spores, and bacterial endotoxins decrease to less than 2.5 microns and simultaneously increase in concentration during rain events. These observations contrast the assumption that rain washes bioaerosols from the air and reduces allergen levels. Instead, population exposures to bioaerosols are expected to be enhanced during rain events.
Exposures to bioaerosols depend on their type, particle size, and concentration. While typically...
Citation
Share