title: Aeroallergen prevalence in the northern New Jersey-New York City metropolitan area: a 15-year summary.
abstract: BACKGROUND
  Elevated environmental pollen levels result in allergic and asthmatic symptoms in sensitive individuals.
  
  
  OBJECTIVE
  To present data collected during a 15-year period demonstrating the seasonal pollen variation in a metropolitan area.
  
  
  METHODS
  Pollen was collected daily except for weekends. Pollen counts were counted using light microscopy and were used to calculate the average daily pollen count per month between March 1 and October 31 of each calendar year. The month in which each class of pollen reached the highest level (peak) was analyzed across the sampling period. Spearman p correlation coefficients were calculated to show changes in peak pollen levels across time.
  
  
  RESULTS
  The average daily pollen level (tree, grasses, and weeds) for each month was analyzed (1987-2002). Tree pollen peaked in May and composed 98.7% of the measurable pollen between March and May. Grass pollen had a biphasic peak (June and September), representing 42.9% of measurable pollen in July and 6.4% in September. Weed and ragweed levels peaked in September. Total weed pollen constituted 93.5% of the measurable pollen between August and October. The combined total pollen levels peaked in May. The highest annual peak tree pollen count was observed between 1992 and 1997, with a linear relationship between tree and total pollen (R2 = 0.97); highest levels of grass pollen were observed between 1993 and 1997; and highest levels of weed pollen were observed between 1993 and 1995. A trend toward declining levels of total pollen was observed between 1993 and 2002. This declining trend was most pronounced for weed pollen.
  
  
  CONCLUSIONS
  Aeroallergens pollinate sequentially, starting with trees in the spring, grass throughout the summer, and weeds in late summer to early fall. Pollen levels have declined from 1993 to the present. The most pronounced drop has been in weed pollen levels. Grass pollen demonstrates a biphasic pattern. Tree pollen composes most annual pollen measured in the northern New Jersey-New York City area.
authors.affiliation: Division of Allergy, Immunology, and Rheumatology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark 07103, USA.
authors.forename: Ava
authors.initials: A
authors.lastname: Port
authors.forename: John
authors.initials: J
authors.lastname: Hein
authors.forename: Alan
authors.initials: A
authors.lastname: Wolff
authors.forename: Leonard
authors.initials: L
authors.lastname: Bielory
mesh_terms: D000397:Air Pollution / Q000032:analysis*; D000485:Allergens / Q000032:analysis*; D009515:New Jersey; D009519:New York City; D006109:Poaceae; D011058:Pollen; D012621:Seasons; D014197:Trees
chemical_list: D000485:Allergens