Whilst I agree with Mike's observation on inhaled atmospheric spore concentrations, I would take slight issue with you Mike (and by remove, with your prof source) on concentration of same in the outside atmosphere, versus an enclosed workshop, where you are flagellating the surface of the spore bodies. I would absolutely like to see your source clip Mike, and am perfectly prepared to admit over-caution or wrong thinking.
Secondly, Adrian, your post:
100% agree. Anyone who works in a garden, or studies trees at close quarters, is exposed to fungal spores constantly. Trees for example are connected to each other via a vast and complex underground fungal network in ways that we still don't properly understand. Visible surface presence is literally the tip of the iceberg.
Conflates the issue slightly. Spores are haploid reproductive bodies, designed (evolved) to be desiccated, and wind-borne. The (sometimes) diploid mycelia underground (and the exudate from them) are more aqueous or mucilaginous and - as recent research now shows - are much more to do with sharing resources and communication than we once realised.
Ergo, spores are much more likely to lead to scenarios like 'Farmers' Lung' whereas mycelial exudate has the potential more dermatitis/urticarial in nature.
I am not preaching, but my Tutor at Uni was a mycologist and he and I had extended chats about moulds in general and ergot, etc in particular, over four years.
A pragmatist inside a perpetual optimist, heavily influenced by an experienced cynic, wrapped around by an aging relic.