Many biologic/chemical TERROR weapons share the aroma of human fartgas.
If you find yourself in a confined space (subway,theater,etc.)
and detect such a smell:
Clearly and LOUDLY ask, "DID SOMEBODY FART?".
If NO ONE answers, YOU MUST follow up with a clear,
" OH MY GOD, WE'RE UNDER ATTACK !!! RUN FOR YOUR LIFE !!! "
Thank you for your cooperation.
A message from the misinformed citizen's bureau.