AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Laboratory Studies of Humidity-Induced Pollen Rupture to Produce Respirable Particles
QIAN ZHOU, Richard Flagan, Timothy M. VanReken, Washington State University
Abstract Number: 462 Working Group: Health Related Aerosols
Abstract Many types of pollen contain allergenic material that has been linked to asthma and other respiratory ailments. However, the physical mechanism by which pollen induces the asthma response is unclear- the pollen grains themselves are too large to reach the lower airways where the asthma response occurs. Recent work has suggested a likely explanation. When exposed to high relative humidity, pollen has been observed to rupture and produce fine particles. The pollen rupture is probably the result of osmotic swelling; water from the surrounding environment is absorbed into the pollen grain until the grain wall fails and the cytoplasm is released. Previous studies have shown that the resulting particles are of respirable size (<2 micrometer) and include allergenic material that can trigger human immune response.
Our focus in this research is to quantify the dependence of pollen rupture on water vapor exposure. For the study, we assembled a small humidity-controlled environmental chamber that can be mounted on a microscope stage. For each experiment, several grains of pollen are placed on a microscope slide, and then exposed to a constant relative humidity for up to several hours. Time-lapse imagery was recorded throughout each experiment. By analyzing the time-lapse images, the relationship between relative humidity, exposure time, and pollen rupture can be determined. These results can then be used to develop a parameterization to allow better model predictions of the allergenic risks from pollen release. The present work focuses on wheat pollen, but future efforts will turn to species more closely linked with allergic response.