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It has been generally believed that due to its relatively large size, pollen cannot reach the periphery of the lung, and thereby induce an asthmatic attack. We have recently discovered mechanisms which explain how allergens housed in large pollen grains can trigger asthma. We have previously established that the pollen, produced during flowering in rye-grass, mostly remains on the open anthers in the absence of wind or other disturbances. If wetted, rye-grass pollen can rupture within minutes. Fragmented cytoplasm is emitted through the pore region of the pollen grain. Drying winds release this cytoplasmic debris directly from the flowers as a respirable allergen-loaded aerosol (see Taylor et al. 2002). The implications of this work are that pollen allergens can be contained in respirable aerosols after moist weather, and these aerosols might deposit into the lower airways where they would be a potent asthma trigger. Pollen grains rupture and the formation of an aerosol of allergen-laden debris of respirable size (less than 2.5 microns in diameter) is common to all the highly allergenic plants so far examined.


To date we have:

1. Conducted weekly pollen and spore counts, expressed in pollen grains per cubic meter of air sampled.
2. Explored the phenomenon of pollen rupture and aerosol formation in a range of plants including many of the most highly allergenic species occurring in Pasadena, as well as some of the most allergenically important plants from around the world.
3. Investigated the formation of aerosols of respirable fragments released from colonies of allergenically important fungi. Allergen-loaded particles of pollen and fungal fragments have been collected using a newly constructed emission chamber.
4. Recorded the physiological responses, including pollen viability, pollen rupture rate and mechanisms involved in pollen release into the atmosphere, for various pollen types after exposure to a range of environmental conditions, such as changes in relative humidity and temperature.
5. Collected outdoor air samples using a MOUDI sampler, Burkard Spore Trap, and a <10 micrometer sampler.
6. Sought to determine the allergen load of aerosols using monoclonal antibodies specific for pollen and fungal allergens with immuno-blots and immuno-cytochemistry.
7. Analyzed the structure of particles released from flowers using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Light Microscopy (LM).
8. Developing Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI TOF MS) methods for detection of pollen allergens.
9. Analyzed Amazon air samples containing high levels of biological aerosols and low levels of pollutants for comparison with Pasadena air.


We are now developing methods to detect whole pollen and fungal spores, as
well as pollen and fungal fragments, in the air. We seek to automatic the capture and analysis of these biological aerosols in as close to real-time as is possible. The tools we are currently utilizing include a range of aerosol particle capture equipment, such as high volume samplers (PM10 and PM 2.5), MOUDI samplers and a Burkard spore trap. Collected particles are then analyzed for allergens with immuno-blots, sandwich ELISA and MALDI TOF Mass Spectrometry. We are also interested in implementing the techniques of molecular biology (e.g. PCR), microscopy-assisted image capture and digital analysis to assist in examining these biogenic particles collected from the air.