A comparative, volumetric survey of airborne pollen in Philadelphia, Pennsylvania (1991-1997) and Cherry Hill, New Jersey (1995-1997)

Background: Aeroallergen sampling provides information regarding the onset, duration, and severity of the pollen season that clinicians use to guide allergen selection for skin testing and treatment. Objective: This atmospheric survey reports: 1) airborne pollen contributors in Philadelphia, Pennsylvania (1991 to 1997) and suburban Cherry Hill, New Jersey (1995 to 1997); 2) pollen onset, duration, and peak level; and 3) the relationship between airborne pollen and selected meteorologic variables. Methods: At both locations, separated by 11 km, sampling was performed with a volumetric Rotorod Sampler (Sampling Technologies, Minnetonka, MN). Results: In Philadelphia and Cherry Hill, respectively, 3-year average measurements included 75.0 and 74.2% tree pollen, 10.2 and 8.3% grass pollen, and 14.8 and 17.5% weed pollen. Prominent airborne pollen taxa were Acer, Quercus, Betula, Pinus, Cupressaceae, Poaceae, Ambrosia, and Rumex. The tree, grass, and weed pollen seasons extended from mid-March to mid-June, late April to mid-June, and mid-August to late September, respectively. A secondary Poaceae pollen peak occurred in September. There was a statistically significant correlation between simultaneous weekly average pollen levels in Philadelphia and in Cherry Hill (Acer, r(p) = 0.987, Quercus, r(p) = 0.645, Betula, (r)p = 0.896, Pinus, r(p) = 0.732, Cupressaceae, r(p) = 0.695, Poaceae, r(p) = 0.950, Ambrosia, r(p) = 0.903, and Rumex, r(p) = 0.572, P <0.001). Daily Poaceae pollen levels were positively influenced by same-day high temperature (r(s) = 0.333 in Philadelphia and r(s) = 0.426 in Cherry Hill, P < 0.05). Daily Ambrosia pollen levels were inversely influenced by same-day total precipitation (r(s) = -0.174 in Philadelphia and r(s) = -0.257 in Cherry Hill, P < 0.05). Conclusions: This is the first volumetric survey performed in either Philadelphia or Cherry Hill. Copious amounts of airborne pollen were seen from late April to early May and in early September. Pollen onset, duration, and year-to-year variability were similar at both sites. An awareness of local aeroallergen patterns is critical in the effective testing and treatment of atopic individuals.