Bizarre dry ice accident kills ice cream seller's mother in Seattle

SEATTLE, Washington -- In a bizarre incident linked to dry ice, one woman died and another is in critical condition in Washington state, authorities said.

An ice cream salesman kept four coolers of dry ice in the back of his car, according to ABC affiliate KOMO in Seattle. His wife had borrowed the car to take his mother home on Friday.

Vapors from the dry ice leaked out of the coolers and flooded the car with carbon dioxide gas, KOMO reported. Hours later, the two women were found in the car on the side of the road, just blocks away from the house.

Hildegard Whiting, 77, died of suffocation from the carbon dioxide trapped in her son's vehicle, according to Pierce County Medical Examiners. Her daughter-in-law was taken to the hospital in critical condition.

Although dry ice is generally harmless, the circumstances led to the deadly situation.

"Dry ice is a solid form of carbon dioxide," according to Martin Cohen, a senior lecturer for the department of environmental and occupational health science at the University of Washington. "Over time, it evaporated directly from solid to produce carbon dioxide gas."

"The effect is going to depend on how much you have of it," he said.