title: Volumetric ragweed pollen data for eight cities in the continental United States.
abstract: BACKGROUND
  A previous report presented volumetric ragweed pollen data for 23 cities in the continental United States. Although helpful, it did not represent all areas of the country.
  
  
  OBJECTIVE
  The purpose of this present communication is to furnish ragweed pollen data for eight additional cities.
  
  
  METHODS
  Ragweed pollen data were obtained from eight pollen sampling facilities in the continental United States. These data were analyzed to determine the length of the season in each city and its peak date.
  
  
  RESULTS
  The ragweed pollen season was typically 2 or 3 months in duration. Ragweed pollen counts reached their annual maximum in late August or early September in cities in Minnesota, Nebraska, and South Dakota. The peak was achieved in late September or early October for two cities in Texas. The annual maximums for three remaining cities in Colorado, Utah and Alabama occurred in late August, early September and mid-September, respectively.
  
  
  CONCLUSIONS
  The findings of this investigation were consistent with previous reports about the north-south nature of the ragweed pollen season. These data, when combined with the results of the 23-city investigation, indicate when source avoidance is most critical in many areas.
authors.affiliation: Multidata, Inc., Minnetonka, Minnesota 55305-1533, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Frenz
mesh_terms: D000407:Alabama; D000485:Allergens; D002947:Cities; D003120:Colorado; D006801:Humans; D008910:Minnesota; D009329:Nebraska; D011058:Pollen; D012621:Seasons; D013023:South Dakota; D013781:Texas; D014589:Utah