An Eight Year Survey (1998-2005) of the Major Tree Pollens in the Washington, DC Area

Abstract

RATIONALE: The last significant sampling for the Washington, DC area was over a decade ago (1989-1994); detailing concentrations and peak pollination periods for 16 major area tree species. The current investigation provides an update to the previous study and allows for comparison with respect to the predominant species and their peak pollinating periods.METHODS: Aeroallergan sampling was conducted using a volumetric rotating arm impaction Rotorod Sampler (Multidata/Sampling Technologies, St. Louis Park, Minnesota). Pollen counts were collected as recommended by the National Allergy Bureau and recorded in grains/cubic meter.RESULTS: The Fagaceae family (oaks and beech) are the predominant pollinating trees; accounting for 47% of the pollen collected. Other identified pollens included 10% Cupressaceae (cypress, juniper, cedar), 9% Pinaceae (pine), 8% Moraceae (mulberry), 5% Betulaceae (birch, alder), and 21% other (each <5%). The peak total pollen count (avg 1275 g/m3) and timing varied between the 2nd week of April to the 1st week of May each year. The most prevalent tree pollens peaked in April or May, except for Cupresseaceae and the alders of Betulaceae peaking in February or March.CONCLUSIONS: As part of a continual aeroallergen survey conducted at Walter Reed Army Medical Center, our data was consistent with previous surveys showing a “tree season” of February to June for this geographic area. Peak total pollen counts appear late in the season with oak as the primary pollinating trees. Further study is needed to establish an area specific severity scale and to correlate these observations with allergic disease outcomes. RATIONALE: The last significant sampling for the Washington, DC area was over a decade ago (1989-1994); detailing concentrations and peak pollination periods for 16 major area tree species. The current investigation provides an update to the previous study and allows for comparison with respect to the predominant species and their peak pollinating periods. METHODS: Aeroallergan sampling was conducted using a volumetric rotating arm impaction Rotorod Sampler (Multidata/Sampling Technologies, St. Louis Park, Minnesota). Pollen counts were collected as recommended by the National Allergy Bureau and recorded in grains/cubic meter. RESULTS: The Fagaceae family (oaks and beech) are the predominant pollinating trees; accounting for 47% of the pollen collected. Other identified pollens included 10% Cupressaceae (cypress, juniper, cedar), 9% Pinaceae (pine), 8% Moraceae (mulberry), 5% Betulaceae (birch, alder), and 21% other (each <5%). The peak total pollen count (avg 1275 g/m3) and timing varied between the 2nd week of April to the 1st week of May each year. The most prevalent tree pollens peaked in April or May, except for Cupresseaceae and the alders of Betulaceae peaking in February or March. CONCLUSIONS: As part of a continual aeroallergen survey conducted at Walter Reed Army Medical Center, our data was consistent with previous surveys showing a “tree season” of February to June for this geographic area. Peak total pollen counts appear late in the season with oak as the primary pollinating trees. Further study is needed to establish an area specific severity scale and to correlate these observations with allergic disease outcomes.