coli unless you got poop and not
a fart on the towel etc. Here is
a link to the composition of
farts. They are mostly gases as you can tell by the smell methane is one of the components or sometimes hydrogen sulfide. Mostly they are made up of hydrogen and nitrogen. Some sugar breakdown may be in there too. So, despite their smell and that they do come from the breakdown of bacteria and food you should be A-OK.
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