Meteorological Influences on Respirable Fragment Release from Chinese Elm Pollen

Abstract

Exposure to airborne pollen from certain plants can cause allergic disease, leading to acute respiratory symptoms. Whole pollen grains, 15-90 µm-sized particles, provoke the upper respiratory symptoms of rhinitis (hay fever), while smaller pollen fragments capable of depositing in the lower respiratory tract have been proposed as the trigger for asthma. In order to understand factors leading to pollen release and fragmentation we have examined the rupture of Chinese elm pollen under controlled laboratory conditions and in the outdoor atmosphere. Within 30 minutes after immersion in water, 70% of fresh Chinese pollen ruptures, rapidly expelling cytoplasm. Chinese elm flowers, placed in a controlled atmosphere chamber, emitted pollen and pollen debris after a sequential treatment of 98% relative humidity followed by drying and a gentle disturbance. Immunologic assays of antigenic proteins specific to elm pollens revealed that fine particulate material (D p < 2 µm) collected from the chamber contained elm pollen antigens. In a temporal study of the outdoor urban atmosphere during the Chinese elm bloom season of 2004, peak concentrations of pollen and fine pollen fragments occurred at the beginning of the season when nocturnal relative humidity (RH) exceeded 90%. Following later periods of hot dry weather, pollen counts decreased to zero. The Chinese elm pollen fragments also decreased during the hot weather, but later displayed additional peaks following periods of more moderate RH and temperature, indicating that pollen counts underestimate total atmospheric pollen allergen concentrations. Pollen fragments thus increase the biogenic load in the atmosphere in a form that is no longer recognizable as pollen and, therefore, is not amenable to microscopic analysis. This raises the possibility of exposure of sensitive individuals to pollen allergens in the form of fine particles that

Chamber catalogues of optical and fluorescent signatures distinguish bioaerosol classes

“…Because of this phenomenon, the EOD distributions for pollen grains are much wider than their fungal or bacterial counterparts, and the means of these distributions are less than unadulterated pollen grains, some of which have true optical diameters larger than 10 µm. These results are consistent with laboratory and environmental studies which indicate that pollen grain fragmentation routinely occurs in the atmosphere (D'Amato et al, 2007;Miguel et al, 2006;Taylor et al, 2002Taylor et al, , 2007. The pollens assembled together based on the ascendancy of type C fluorescence and their markedly higher fluorescence intensities relative to the other bioaerosol classes observed (Fig.…”

Elastic Light Scattering on Single Pollen: Scattering in a Large Space Angle

“…This deformation could be reversed by putting the pollen into ethanol or water shortly before the measurement. As mentioned in the literature (Miguel et al 2006) we observed that pollen undergo an osmotic shock when immersed into a liquid. Potentially, the cytoplasmic material spilled out of the pollen has affected the scattering pattern.…”

Primary biological aerosol particles in the atmosphere: a review

“…Pollen grains occur as biological aerosols not only as complete units but also as fragmented pieces. Pollen can rupture when the humidity is high, and these fragments have been shown to be in the range from 30 nm to 5 mm (Taylor et al, 2002Miguel et al, 2006). Pollen of anemophilous plants use wind as their dispersal vector and have a typical diameter of 17Á58 mm (Stanley and Linskins, 1974;Kuparinen, 2006;Nathan et al, 2008;Pope, 2010).…”