(117d) Physical Control of Pollen Grain Rupturing

Grass pollen is the hypothesized cause of a dangerous event known as thunderstorm asthma, when nanoscale allergenic particles are released from pollen grains inside a thunderstorm cloud. On November 21, 2016 the worst recorded thunderstorm asthma event occurred in Melbourne, Australia. In a single day thunderstorm asthma killed ten people and sent thousands to emergency rooms with asthma symptoms, many without any prior history of asthma. Despite the danger associated with this phenomenon, its mechanism has not been fully verified because of the extreme nature of the conditions required. This work provides direct microscopic observations of rapid pollen rupture due to extreme variations in temperature and osmotic pressure. A novel microfluidic chamber is used to carefully control time and concentration gradients in order to approximate the extreme meteorological conditions in active storm clouds. Fluorescence microscopy is used to track rupture mechanism and extent as well as release of lipid and protein components of the pollen, allowing us to more exactly model the criteria for dangerous events. Multiple-particle tracking techniques are used to assess the transport and interactions of the released components with model and biological fluids like mucus.