Patterns in airborne pollen and other primary biological aerosol particles (PBAP), and their contribution to aerosol mass and number in a boreal forest

We studied variation in concentrations of airborne pollen and other particles of biological
\norigin in a boreal forest in Finland during 2003–2004. The highest concentrations of pollen
\nwere observed in late spring and early summer, whereas the peak concentrations of other
\nparticles of biological origin (including e.g. fungal spores) occurred in August–September.
\nAlthough the patterns in concentrations in 2003 and 2004 were similar, the concentration
\nlevels were significantly different between the years. The contribution of pollen and other
\nparticles of biological origin led to an increase in the measured particulate matter (PM)
\nmass during the pollen season (mass of pollen and other particles of biological origin 5.9
\nand 0.4 μg m–3, respectively, in respect to PMtotal mass of 9.9 μg m–3) but the effect on
\ntotal particle number was negligible. The other particles of biological origin constituted the
\nlargest fraction of measured primary biological aerosol particle (PBAP) numbers (~99%),
\nwhereas pollen showed a higher relative mass fraction (~97%) of PBAP. These results
\nunderline the important contribution of PBAP to coarse atmospheric particle mass providing
\nup to 65% of the total mass during the peak pollen season.