Mountain cedar (Juniperus ashei) pollen is one of the most potent airborne allergens in the United States. Populations of mountain cedar occur in south central Oklahoma and Texas. Although none occur within 200 miles of Tulsa, over the past 17 years we have shown evidence for significant concentrations of mountain cedar pollen being carried to Tulsa by prevailing southerly winds. During December and January, cedar pollen typically appears in the Tulsa atmosphere on 30% of the days with concentrations as high as 2400 grains/cubic meter of air. Although no local populations of cedar pollinate at this time of the year, mountain cedar does pollinate during these months. High concentrations in Tulsa occur on days with southerly winds suggesting that the mountain cedar populations in southern Oklahoma and Texas are the source of this pollen.
During the past two years, efforts to document the long distance transport were increased with data from five sampling stations. The main sampling station was located on the roof of a building at The University of Tulsa. During the 1996-1997 season, the other samplers were located at ground level in conjunction with Oklahoma Mesonet meteorological stations south of Tulsa. During the 1997-1998 season one of the traps was moved to a rooftop at the University of Texas in Austin. The Austin trap located at the edge of the mountain cedar population provided an estimate of the source strength near the main population. During these two seasons 5 major episodes of long distance transport occurred. Analysis of the meteorological conditions reinforced earlier observations that the presence of pollen in Tulsa only occurred when winds were coming from the south.
A forecasting system is being developed for the coming winter to predict the dispersal of mountain cedar pollen in the south-central region of the United States. In cooperation with the Mesonet, forecasts will be issued based on the presence of airborne pollen and climatic conditions. Meteorological trajectories from source areas will operate on various weather forecasting models used nationally by the U.S. Air Resource Laboratory, Silver Springs, Maryland to predict 48-hour weather and wind fields. The models will plot the atmospheric pathway of a “pollen-cloud” for 48 hours into the future. Forecasts will be updated several times each week during December and January and will be available on the World Wide Web.