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.

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.

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.

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).