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Background Local aeroallergen surveys identify and establish patterns of prevalence for tree, grass, and weed species that enable the clinician to more effectively select allergens for skin testing and therapy. Objectives To determine peak pollination periods, atmospheric concentrations, and year-to-year variation for identified tree, weed, and grass aeroallergens and examine the influence of selected meteorological parameters. Methods Atmospheric sampling for pollen aeroallergens was performed using a volumetric rotating-arm impaction sampler. The Spearman correlation coefficient was used to determine the relationship between daily counts and selected meteorological parameters. Results Previous findings for area trees, conducted at a different location, are corroborated. Predominant pollen types include Quercus , Cupressaceae, Pinaceae, Morus , Betulaceae, Acer , Platanus , Fraxinus , Poaceae, and Ambrosia . Early flowering weeds ( Rumex and Typha ) and Poaceae overlap with peak tree season in April. Biphasic seasons are noted for Poaceae and Ulmus . Tree pollen accounts for 91.2%, weeds 3.8%, and grasses 3.2% of total annual pollen yield. Variation in overall pollen production is evident from year to year. High production years for some species are low for others. Cyclic pollinating patterns for Alnus , Betulaceae, and Fagus were observed. Grass and weed pollen correlated positively with maximum temperature and dew point; however, the results for individual tree species were variable. Conclusion The Washington, DC, metropolitan area is host to a variety of tree, weed, and grass species that produce copious amounts of pollen. Further investigation into year-to-year variation with respect to inherent cycling and meteorological influences is warranted.

Aliment Pharmacol Ther 31, 509–515 Summary Background Aeroallergens have been implicated in the pathogenesis of eosinophilic oesophagitis. Aim To determine whether a seasonal variation exists in the diagnoses of eosinophilic oesophagitis and whether there is a correlation with seasonal pollen count. Methods A retrospective review was performed from January 2006 to November 2008 to identify eosinophilic oesophagitis patients. Cases were classified by endoscopic date. Daily pollen counts for grass, trees and weeds were obtained from a certified counting station. Per cent of eosinophilic oesophagitis cases were collated seasonally and compared with mean pollen counts for grass, trees and weeds during the same time period. Results A total of 127 eosinophilic oesophagitis cases were identified (median age 41, range 19–92 years, 84% men). The highest percentage of cases (33.0%; Binomial P = 0.022) was diagnosed in the spring, while the least percentage (16%; Binomial P = 0.0.010) occurred in the winter. There was a significant association between per cent eosinophilic oesophagitis cases diagnosed seasonally and mean grass pollen count (rs = 1.000, P

Objective A 6-year (1989 to 1994) aerobiologic survey of the Washington, DC area was performed to identify predominant area tree pollens, atmospheric concentrations, and peak flowering periods. Methods Aeroallergen sampling was conducted using a volumetric rotatingarm impaction Rotorod sampler (Sampling Technologies, Inc, Los Altos Hills, California). Results The Washington, DC pollen calendar may begin as early as January when pollen of the Cupresseacea, Aceracea, Pinaceae, and Betulaceae are observed in small amounts. February through June encompasses the major part of our tree season with considerable overlapping of pollination periods for various trees. The Ulmaceae have two distinct pollinating times with later flowering species of elm pollinating August through October coinciding with ragweed season. April is usually the month with the highest weekly average concentrations. Each year oaks contribute more than 50% of the total tree pollen count followed by pollen of the Pinacea, Cupresseacea, Moracea, and Betuleacea. Times for onset of pollination as well as peak atmospheric concentrations varied from year to year. High production years for some tree aeroallergens are low years for others. Conclusion The Washington, DC area is exposed to significant atmospheric concentrations of tree pollen from February through June. Establishing what area tree aeroallergens predominate with respect to their atmospheric concentrations and peak pollinating times is essential for the effective diagnosis and treatment of the tree-allergic patient.

Background Local aeroallergen monitoring provides useful information for the atopic patient and medical community. Currently, National Allergy Bureau (NAB) ranges are used for reporting pollen count levels in the Washington, DC, area. Objective To determine standard range criteria (low, moderate, high, and very high) for the reporting of specific tree, grass, and weed aeroallergens representative of the Washington, DC, metropolitan region. Methods Atmospheric sampling for pollen aeroallergens was performed using a volumetric rotating-arm impaction sampler (model 40 Rotorod, SDI Company, Plymouth Meeting, PA). The cumulative pollen count, over a 12-year period (1998–2009), was determined for specific pollen aeroallergens. Local ranges were developed using methodology previously employed to determine NAB ranges. A comparison was made between NAB and Washington, DC, area ranges. Results The local median count, and low and moderate range criteria, are markedly lower than NAB range counts for tree, grass, and weed pollen. The NAB 99th percentile (high) count is significantly higher for grass and weed pollen but lower for tree pollen. Using new local range criteria, an increase was seen in the number of high days recorded for weed pollen (1,300%), grass pollen (258.6%), and tree pollen (11.8%). Previously, using NAB range criteria, no very high days were reported for grass and weed pollen over the 12-year period. Conclusion Washington, DC, ranges establish more relevant reporting standards for our local patient population and will allow for comparison with reporting levels developed for sampling locations nationwide as well as with other regional sites.