Areas Within Isopleths of Ragweed Pollen Concentrations From Local Sources

Abstract

Areas within which ragweed (Ambrosia) pollen concentrations equaled or exceeded selected values were determined from measurements around ten experimental ragweed sources. These areas were related to source size, surrounding vegetative cover, and meteorological conditions. Areas from 6 to 100 times the source area had mean concentrations above 100 grains/cu m while concentrations above 10 grains/cu m were found over areas from 11 to 300 times the source area. The size of the polluted area was related directly to source size and inversely to wind speed and the removal efficiency of surrounding vegetation.