Human health risks w/ cat pooping in crawl space?

My house sits atop 3 foot piers making a crawl space the size of the entire
house's floor plan - 1200 sq ft. For a time I allowed him down there (thru a
special cat door) so he could have fun playing in the dirt and catching
small lizards and gecco's. (He's an indoor cat) He took to preferring the
dirt to his cat box, much to my approval. I've closed his door to the crawl
space to monitor a health problem that has cleared up, and am considering
letting him back down there and stowing the cat box away.

Questions a

Will the poop decompose down there, in dirt that gets no rain?

Is there a health risk to me in the house after a long period of poop
build-up down there? I'm thinking, maybe small poop molecules will work
there way into the house thru the floor(?).

In the 3 months that he was down there, I did not smell anything in the
house. I even crawled around there, even over the area he preffered to do
his business (of course he buried his stuff). I did smell evidence of his
business (only while I was crawling directly over his buried stuff), but it
wasn't overly strong.

Anyone else allow their cat to poop in the crawl space under their house?

Any educated guesses as to possible negative side affects to the humans in
the house to the cat pooping down there long-term?

Thanks!
Hank