Moreover, some fungi are major pathogens and allergens. The diversity of airborne fungi is, however, not well-known. By DNA analysis we found pronounced differences in the relative abundance and seasonal cycles of various groups of fungi in coarse and fine particulate matter, with more plant pathogens in the coarse fraction and more human pathogens and allergens in the respirable fine particle fraction (<3 μm).
Some fungi are major pathogens or allergens for humans, animals, and plants, and air is the primary medium for their dispersal (18–20), but the diversity of fungi in air particulate matter is not well-known.
Note that fine particles have longer residence times in the atmosphere (multiple days to weeks) and that they can reach the alveolar region of human lungs upon inhalation, whereas coarse particles are rapidly removed from the atmosphere (sedimentation, scavenging, and precipitation) and are deposited in the upper airways when inhaled. Thus, the scientific investigation and public discussion of climate and health effects are mostly focused on fine aerosol particles (11).