MOORE, Okla. - The immediate danger from the Moore, Okla. twister may have passed, but it has left behind an invisible threat that could be just as deadly.
"Tornado cough" is an allergic reaction to debris in the air and it can affect even the healthiest people.
Drywall, fiberglass and mold don't normal affect the average person, but when they're mixed together in the air they can bombard the respiratory system.
"You don't have to have asthma to overwhelm your respiratory system," said Dr. Jason Sigmon, a sinus and allergy specialist. "We saw that in 9/11 after the World Trace Center bombings and all the debris that was in the air."
Tornado cough can be deadly if particulates are breathed over a long period of time.
Doctors say the best defense is to wear a mask when around debris.