It's bound to happen, but I really wish it wouldn't

I'm minding my own business, riding the skytrain at the end of the day. When suddenly, seemingly out of nowhere, a cloud of stench wafts passed my nostrils, followed by the immediate and horrid realization that it has happened. Someone farted on the skytrain. Now maybe this isn't the worst of all possible offenses, after all it is transient and occasionally unavoidable. However, it's also unexpected and anonymous. This means you can't escape it or prepare for it; it's not like the guy talking to himself or a woman with a screaming toddler - the trouble you can see coming. There's also no one to blame, because last I checked, no one is holding up a sign that says, "It was me. I farted." So now there's not even anyone to be mad at. So tempting as it may be to let one rip while riding transit, perhaps you could not ... or at least wait for the doors to be open so the draft can clear the smell.