Yes farts do contain poop particles but they're so tiny that you can't see those tiny poop particles flying through the air when you do fart that is if you're naked when you fart.
When you have clothing on and you fart poop particles will still fly out your anus and land in your underwear or pants but you really can't see them since they're so tiny.
The particles are what is really responsible for the smell of the fart.
So if someone farts in your face when they pull there pants down to fart in your face then you'll likely get poop particles in your nose or mouth.