VARIATIONS IN AIRBORNE POLLEN ANTIGENIC PARTICLES CAUSED BY METEOROLOGICAL FACTORS

High birch pollen antigenic activities in outdoor air samples were fou nd in all particle sizes studied (> 7.2, 2.4-7.2, < 2.4 mum and molecu lar size class, with an ELISA modification). Sampling was done with a low-volume, size-selective bioaerosol sampler (SSBAS) simulating the h uman respiratory tract in both volume and fractionation. Airborne birc h pollen counts for comparisons were obtained from a Burkard trap. No correlations were obtained between antigen concentrations in any parti cle size fraction and airborne pollen counts. The meteorologic factors studied differed clearly in their effect on antigenicity, depending o n the size class studied. Likewise, the effect of meteorologic factors differed among the three study periods (period I, 4 weeks before the peak pollen season; period II, during the season; and period III, 4 we eks after the season). During the peak pollen period, temperature and relative humidity were the most important meteorologic factors. Before the season, large and very small particles predominated, medium-sized particles being totally absent. The largest size class studied (conta ining all intact pollen grains) clearly reacted to changes in meteorol ogic factors; for smaller size classes, these factors were found to be less important, a fact which may make the forecasting of antigen conc entrations in the air on the basis of meteorologic data impossible.