The generation and distribution of airborne bioparticulates are sensitive to meteorological events. Precipitation and extreme temperatures are known to reduce airborne pollen concentrations either directly by inhibiting pollination or indirectly by lowering the population of pollinating plants. Tree pollen generation, however, is generally considered to be more resistant to local weather conditions. In order to examine the impact of the January ice storm in Kansas City on tree pollen production we conducted the following studies.

Airborne pollen was collected in the Kansas City area during tree pollen season (Feb 15 to May 15) for the years 1997 to 2002. Pollen grains were collected every 4 hours on silicon grease coated glass slides using an Allergenco MK-3 spore trap collector. Slides were stained and preserved with Calberlas stain in glycerin jelly and counted microscopically at 400x. Pollen numbers were entered into an Access database. Weather data was obtained from an Automated Weather Source station located adjacent to the collector.

The data encompasses the total seasonal pollen counts for 10 major tree pollen types found in the Kansas City Area. These are Ash (Fraxinus),Birch (Betulaceae), Cottonwood (Populus), Elm (Ulmus), Juniper (Cupressaceae), Maple (Acer), Mulberry (Morous), Oak (Quercus), Pine (Pinaceae) and Walnut (Juglans). The highest counts are typically oak with seasonal values exceeding 3000 counts for a 20 day season yielding average daily counts of 166 grains per cubic meter of air and peak counts upwards of 2000 grains per cubic meter of air. Four types, elm, mulberry cottonwood and walnut had lower counts in 2002 than in 2001; however, none of these had their 6 year low in 2002. Four types, Oak, Ash, Birch and Juniper were higher in 2002 than in 2001, with Oak, Juniper and Birch having 6 year high levels in 2002. Oak pollen showed a six year high in 2002 with 8723 total counts for the season and highest concentrations of 3613 grains per cubic meter of air on 4-19. Previous high oak levels occurred in 2001 on 4-21 with concentrations of 2200 grains per cubic meter of air. Elm trees suffered the greatest decrease in pollen production as a result of the ice storm of January 31. Total counts for 2002 were less than half of the counts in 2001. Yet, 2002 counts were still higher than 2000 counts. Peak elm concentration in 2002 was on 4-12 with 453 grains per cubic meter of air as compared with highest elm concentrations in 2001 on 3-9 with 353 grains per cubic meter of air and in 2000 on 3-20 with 328 grains per cubic meter of air..

Catastrophic weather events can have clear impact on tree pollen production. These impacts tend to be specific in nature and are not easily generalized to the entire repertoire of pollinating trees. There was a specific reduction in elm pollen as a result of the ice storm, but other trees that pollinated later in the year did not have any noticeable reduction in pollen production.