AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Meteorological Influences on the Size and Concentration of Airborne Pollens
CHATHURIKA RATHANYAKE, Josh Kettler, Thilina Jayarathne, Elizabeth Stone, University of Iowa
Abstract Number: 424 Working Group: Bioaerosols
Abstract Bioaerosol (e.g. plant pollens, fungal spores, bacteria, and viruses) are aeroallergens, exacerbating asthma and respiratory conditions. This study focuses on defining the temporal variation, size distribution, and mass contribution of bioaerosols to ambient particulate matter in the Midwestern US. The size of pollens was determined by microscopy and chemical profiles were developed for dominant pollen types in the Midwestern US, including red oak, pin oak, corn and ragweed. Glucose, fructose and sucrose accounted for 5 - 14% of pollen mass, supporting their use as chemical tracers of airborne pollens. Each pollen type had a unique ratio of glucose : sucrose : fructose, indicating that the relative abundance of these saccharides may be used for identifying pollen types in atmospheric PM samples. Saccharides were measured in fine and coarse particulate matter (PM$_(2.5) and PM$_(10-2.5), respectively) during tree pollen season (spring) and ragweed season (late summer) in Iowa City, IA in 2013. Pollen tracers were predominantly observed in coarse PM. However, during heavy spring rain, ambient concentrations of pollens significantly increased (p<0.001) and decreased in particle size, such that they were dominant in the fine mode. The decrease in the pollen size is likely due to osmotic rupture of pollen grains upon saturation with rainwater, causing them to burst and release pollen fragments less than 2.5 microns. This decrease in particle size is significant, because the pollen fragments can penetrate more deeply to the human respiratory tract and exhibit enhanced health effects. Red oak was identified as the likely pollen type contributing fine mode pollen fragments and was estimated to account for 73% of PM$_(2.5) and 15% of PM$_(10-2.5). Overall, human exposure to fine pollen particles, which can reach deeper in to the respiratory tract can be enhanced during rain events, increasing respiratory symptoms, even when total particle levels are low.