Vital Signs Blog

Chemistry 101: Oxygen is not flammable

High concentrations of oxygen used during surgeries are a potential fire hazard for patients, but that doesn't mean the O2 gas itself catches fire.

This week's Modern Healthcare cover story spotlighted the slow adoption rate of surgical-fire-safety techniques among hospitals and surgery centers.

Highly concentrated oxygen is a factor in four of every five fires in the operating room, and about a third of the hundreds of OR fires per year are believed to injure patients. Easy steps to prevent virtually every such fire are readily available from the Anesthesia Patient Safety Foundation.

However, some scientists who read the story noted that it may fuel a widespread misunderstanding that oxygen is flammable.

“It is a common misperception in the clinical community and in the general public. The technical reality is that the oxygen doesn't burn,” said Mark Bruley, vice president for accident and forensic investigation at ECRI Institute. “It's a subtlety of the physics of fire. Oxygen makes other things ignite at a lower temperature, and burn hotter and faster. But oxygen itself does not catch fire.”

So, for example, an incident reported by hospital inspectors as an “oxygen fire” in a surgical mask is actually the plastic of the mask catching fire because purified oxygen has lowered its ignition temperature to create a flash fire. Plastic tubing, fine body hair, surgical sheets—these are the “fuels” of the fire, not the oxygen, which acts an “oxidizer” in purities above 35%, the Food and Drug Administration explains.

Experts stress, however, that that oxygen should still be handled with care. It is in fact the primary cause of most hospital fires, even if the oxygen itself is not burning. The best strategy is to always use the lowest possible concentration of oxygen by taking the extra step to hook up an air-oxygen blender to mix concentrated oxygen with regular air, experts say.

Follow Joe Carlson on Twitter: @MHJCarlson


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