The diurnal variation of air-borne ragweed pollen as determined by a continuous recording particle sampler and implications of the study

Abstract

A continuous recording volumetric sampler was placed in operation during the entire ragweed season after the efficiency of this sampler was determined in terms of Ambrosia trifida. An analysis of these twenty-four hour volumetric air samples revealed: 1. 1. The most critical period in exposure of the patient to ragweed pollen is during the hours from 9:00 a.m. to 1:00 p.m. Sixty-seven per cent of the pollen collected during the month of August was collected from 9:00 a.m. to 1:00 p.m. Fifty per cent of the pollen collected during the month of September was collected during this same time period. 2. 2. Only 10 per cent of the pollen collected for the twenty-four hour periods was collected from 6:00 p.m. to 6:00 a.m. during the months of August and September. 3. 3. A comparison of volumetric air samples with ragweed pollen counts made with a standard sampler located at the same sampling site shows no particular advantages in the use of a volumetric sampler in indicating the beginning, the end, and the apex date of ragweed pollen. 4. 4. Certain meteorological factors in determining the ragweed pollen incidence are mentioned and the implications of this study are discussed.