i wouldnt fret too much. the krausen should protect it from the crap in the air. ive had a blow off tube get clogged and explode in the past, and my beer was fine.
"I'm not telling you, 'Never eat a hamburger'. Just eat the good ones with real beef, you know, like the ones from that Mom-and-Pop diner down the street, and it's so good that when you take a bite out of that burger, you just know somewhere in the world a vegan is crying." Homer Simpson