Two women were found unresponsive in a car along with the likely culprit -- four coolers of dry ice -- Friday morning in Pierce County, Washington, CNN affiliate KOMO reports.
The owner of the car, an ice cream salesman, called 911 when he found his wife and his mother on the side of the road blocks from his home, according to the station. His 77-year-old mother is reported to have died of suffocation, and his wife to have been in critical condition.
"His mom and his wife got in the vehicle to give his mother a ride home," Detective Ed Troyer, a spokesman for Pierce County Sheriff's Department, told KOMO. "The fumes escaped from the coolers."
Dry ice is frozen carbon dioxide -- the same molecule we exhale in gaseous form. But as it enters a warmer environment, instead of melting into a liquid, it transforms directly from a solid to a gas, which is odorless and colorless.
In most open spaces and with proper handling and ventilation, it doesn't pose a threat. But in closed spaces, that carbon dioxide can quickly build up, displacing the oxygen, experts say.
"It was a combination of things that went terribly wrong," Troyer said, noting that the car may have not been adequately ventilated for its cargo.
"Your heart and your brain are going to lack an amount of oxygen needed to survive. You will go in a coma very quickly, and your heart is going to stop beating," said Dr. Kris Permentier, head of the emergency department at a hospital called az Sint-Blasius in Dendermonde, Belgium, about 30 kilometers from Brussels. Permentier published a report about carbon dioxide poisoning last year, calling it an "often forgotten cause of intoxication in the emergency department."
However, it is rare to see in the hospital because "in the majority of cases, all emergency department services arrive too late," he said. In enclosed spaces with very high levels of carbon dioxide, people can die within minutes.
The man who owned the car works at a Dippin' Dots franchise in Tacoma and is not an employee of the corporation, Dippin' Dots LLC, the company's CEO Scott Fischer confirmed.
"This horrific accident has shaken our entire business family and our thoughts are with our longtime franchisees and their employee," Fischer said in a statement. "We take dry ice handling precautions and safety procedures very seriously, and this incident is a painful reminder for all of us who handle dry ice of the inherent dangers of working with the product."
Fischer also noted that dry ice safety practices are addressed in the company's franchise operations manual, and that the company also provides in-person dry ice safety trainings for its franchises.
The incident in Washington bears similarities to a case described in a 2004 report by the US Centers for Disease Control and Prevention in which an Alabama man bought dry ice anticipating a power outage after Hurricane Ivan. He transported a 100-pound block, divided into four brown paper bags, with the windows closed and the air conditioner recirculating the air inside his pickup truck. After driving only a quarter mile, the man began to have difficulty breathing, pulled into a parking lot and passed out. Fortunately, he had alerted his wife, who found his truck. She opened the door, and immediately her husband began to awaken. Aside from a headache over the next day, the man made a full recovery.
The CDC report describes how the body responds to changes in carbon dioxide in the blood: Initially, an increase in carbon dioxide causes you to breathe faster. In closed spaces with dry ice, heavier breathing draws even more carbon dioxide into the lungs, which can lead to a number of symptoms of oxygen deprivation, including "headache, confusion, disorientation, and death." These changes "can occur within seconds of exposure to high levels" of carbon dioxide, the report says.
But soon enough, high carbon dioxide and low oxygen will slow things down: Breaths become slower and shallower, and the heart begins to contract with less force, Permentier said.
You might not even realize you're being deprived of oxygen, he added.
"You feel sleepy, dizzy, but you don't have the intention to open up the air," said Permentier. "You don't have the strength [or] the brain capacity to open up the doors or the windows."