Federal officials are calling the recent spate of oil refinery fires and explosions an ominous red flag for the millions of Americans who live near the massive industrial sites, and they have advice for responding in the case of a catastrophic release of deadly chemicals.
In the case of a release of a cloud of deadly hydrofluoric acid, which can float for miles along wind currents, scientists say the best approach is to stay put.
"A house offers you a chance to close all the doors and windows -- hopefully they're already closed by the time the cloud hits, and a shelter in place," said Dr. Ronald Koopman, a retired government scientist, in an interview with ABC News. "And shelter in place is about all you can do if you're in neighborhood where a cloud like this is created and it passes over. The house will exclude a lot of that cloud from getting in, depending on how tight it is."
CLICK HERE for a slideshow about aging oil refineries in America.
Koopman's advice corresponds with that of the Centers for Disease Control and Prevention, which writes on its web site that the only options in the case of a gas release are to evacuate or stay put. "If you are near a release of fluorine or hydrogen fluoride, emergency coordinators may tell you to either evacuate the area or shelter in place inside a building to avoid being exposed to the chemical," the CDC web site says. Another government web site offers advice for sealing a room.
CLICK HERE to watch a giant hydrofluoric acid cloud form.
'If It's Good and Tight, You Can Be Protected'
Koopman tells ABC News that sealing a room is important if there's a gas cloud looming. "If there are cracks, if it's leaky, if you have windows open, if you have a fan on that's bringing air in, then it's going to bring the outside right in. If it's good and tight, and everything is closed, you can be protected for possibly the duration of the release."
CLICK HERE to watch an interview with a victim of hydrofluoric acid inhalation.
Hydrofluoric acid can scar the lungs and can cause death by asphyxiation. It can penetrate human skin and react with calcium in bones.
A joint investigation by ABC News and Center for Public Integrity that aired Thursday on World News with Diane Sawyer and Nightline found that 16 million Americans live within range of potential toxic plumes from 50 aging refineries that employ hydrofluoric acid in the refining process. Los Angeles, Philadelphia, Minneapolis, New Orleans and portions of the Texas Gulf Coast are among the at-risk areas cited in documents filed by the oil industry with the federal government.
CLICK HERE for an interactive map of oil refineries in America.
CLICK HERE to read the Center for Public Integrity's story on oil refineries.
The Center for Public Integrity is a nonprofit, investigative reporting outlet in Washington, D.C.