Fungal spores are present all over in the air around us. I understand that they generally range in size from about one to one-hundred microns.

What is the number density of fungal spores in air on a volume basis? I imagine this will vary based on location, season, and indoor vs. outdoor. An ideal answer would account for all of this in the ranges but I'm broadly interested in indoor air conditions around the world.

If measurements of a single spore density are too difficult, I would find the density of CFUs to be acceptable (assuming that those are multiple spores) but would appreciate being directed to information on how many spores typically make up one CFU. Similarly, a mass density of spores would be acceptable as well if experimental methods make that easier. At the simplest level, I'm just curious how much fungal spore material is in the indoor air around us.


1 Answer 1


Bamba et al. (2014) Case study of airborne fungi according to air temperature and relative humidity in houses with semi-basements adjacent to a forested hillside. Biocontrol Sci. 19: 1-9.

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This is neither the first nor the last report of this kind. Search PubMed database using this query:

"air"[Title/Abstract] and "fungi"[Title/Abstract] and "spore"[Title/abstract]
  • $\begingroup$ This is very helpful. Thank you. I see that CFUs really seem to be the standard on this as you can more easily count cultures than individual spores. Any guidance on mass or number of spores per CFU? $\endgroup$ Sep 20, 2018 at 12:48
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    $\begingroup$ Assuming (1) the sample is properly diluted and (2) each spore germinates: 1 spore ~ 1 CFU. $\endgroup$
    – user37894
    Sep 20, 2018 at 15:50

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