The New Haven Fire Department detected carbon monoxide levels "about 10 times the safe amount" at the site
Nine of those hospitalized were construction workers, while the remaining five were Yale University employees, according to the Associated Press. Four of those who were hospitalized have since been discharged, while the remaining 10 are still being monitored by medical professionals, per USA Today.
Emergency responders were notified around 7:30 a.m. that a construction worker was found unconscious on a sidewalk. The worker was taken to Yale New Haven Hospital and treated for extremely high levels of carbon monoxide in his bloodstream. He was later transferred to a hyperbaric chamber at Jacobi Medical Center in New York, reports Yale News.
The worker's diagnosis prompted the discovery of nearly lethal levels of carbon monoxide in the building, where New Haven’s emergency operations director Rick Fontana said emergency responders discovered 13 other people complaining of headaches, according to USA Today.
Mayor Justin Elicker told USA Today that after checking for a gas leak, the New Haven Fire Department detected carbon monoxide levels "about 10 times the safe amount."
Fontana explained the building had a carbon monoxide level of 350 parts per million. He said that a typical home carbon monoxide detector would alert people when it detects 35 parts per million. “That carbon monoxide, it’s not like you could smell it or see it or feel it,” Fontana explained. “Everybody thought that it was being vented properly until we were notified of this group of people."
New Haven Fire Department Chief John Alston explained to the New Haven Independent that the building’s ventilation may have been affected due to the winter temperatures and as a result worsened the leak’s effects.
“When you're using gas-powered tools, you should be monitoring inside the building. You want proper ventilation, you want to have air monitoring,” Alston recommended.
Elicker told USA Today that the construction site was using a propane-fueled saw. "When using that type of equipment, you are supposed to be in an area that's properly ventilated and using carbon monoxide monitors. And they were not using carbon monoxide monitors. It appears they did not realize that there was so much carbon monoxide in the air."
The mayor added that the Occupational Safety and Health Administration (OSHA) has begun an investigation into the accident and a stop work order for the site has been administered.
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Carbon monoxide poisoning symptoms include headache, dizziness, weakness, upset stomach, vomiting, chest pain, and confusion, according to the CDC.
Representatives for Yale University, Mayor Elicker, OSHA and New Haven Fire Department did not immediately respond to PEOPLE’s request for more information on Thursday.
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