Interpretation of pollen exposure data

Abstract

Rationale Aerobiological sampling traditionally uses a spore trap located in a fixed location to estimate exposure to airborne pollens and fungi. We examined pollen counts made with a spore trap and personally worn pumps with the amount of pollens actually inhaled by people. Methods Pollen was collected with a Burkard spore trap (10L/min) in a park while 30 adult subjects used nasal air samplers (NAS) for 2 hours on 2 separate days. Four subjects also wore personal IOM filter samplers operating at 2 L/min. The NAS were previously shown to collect 97-99% of pollens. All subjects were in close proximity and performed similar low-level physical activities. Results Comparing counts for each day by each method indicated wide variation in the relative counts. Total pollen counts were higher on Day 2 compared to Day 1 for NAS, pump and spore trap by factors of 2.7, 1.7 and 5.5 fold respectively. On Day 2, inhaled geometric mean pollen counts over 2 hours by NAS were 53.4 (range 1-1699) for Ambrosia and 9.8 (range 2-32) for Poaceae pollen. The corresponding spore trap counts for this period were 93.5 Ambrosia and 44 Poaceae and mean personal IOM counts were 64 Ambrosia and 3 Poaceae. Conclusions The three methods gave markedly different relative counts from day to day. Personal exposure to pollen in people in the same location and performing similar activities can vary by 13-40 fold (5-95% percentiles).