A comparison of ragweed pollen incidence in the United States for 1929 and 1930

Abstract

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.The purpose of this present communication is to furnish ragweed pollen data for eight additional cities.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.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 Colorodo, Utah and Alabama occurred in late August, early September and mid-September, respectively.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.