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Pollen Grains Rupture in Wet Weather

Fragments are small enough to enter the lower airways and trigger asthma symptoms

WEDNESDAY, Nov. 9 (HealthDay News) -- Although whole pollen grains are considered too large to enter the lower airways and trigger asthma, the grains may rupture during wet weather into an inhalable size, according to research presented this week at the American College of Allergy, Asthma and Immunology annual meeting in Anaheim, Calif.

M. Michael Glovsky, M.D., of the Huntington Medical Research Institute, Pasadena, Calif., and colleagues studied pollen fragmentation in a plexiglass chamber. They also constructed a wind tunnel to determine the wind velocity at which flowers emit pollen and pollen fragments.

The researchers found that whole pollen grains rupture when exposed to a relative humidity greater than 96%, creating fragments small enough to enter the lower airways. They also found that a wind velocity of 6 mph is enough to release allergenic pollen fragments into the atmosphere.

"We propose that a combination of inhaled nanoparticles and aromatic hydrocarbons, from the combustion of fossil fuels, and inhaled pollen fragments are responsible, in part, for the increase in asthma in the last 50 years," the authors state.

Abstract (#16, P.8)

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