The Courtyard by Marriott was evacuated Sunday morning shortly after 10 a.m. after four employees suddenly fell ill from carbon monoxide exposure.
The Chattanooga Fire Department was called to the Marriott at 200 Chestnut St. on a medical call, according to department spokesman Bruce Garner.
Capt. Mark Shook with Quint 1 said the firefighters were directed to the break room in the basement, where paramedics with Hamilton County EMS were examining two employees who complained of nausea and dizziness.
"When firefighters were told that several other employees were also feeling sick," Mr. Garner said, "Capt. Shook had reason to believe that there might be more involved than individual illnesses and ordered the immediate evacuation of the entire building."
EMS took four employees, all women, to Erlanger hospital for treatment.
Capt. Wade Batson with Hamilton County EMS said three of the four employees taken to Erlanger showed significant levels of carbon monoxide poisoning. The plan was to treat them in a hyperbaric chamber to remove the carbon monoxide from their bloodstreams.
Carbon monoxide is a toxic gas that is colorless, odorless and difficult to detect without special instruments. Tactical Services Chief Danny Hague said that determining the origin of the carbon monoxide may be difficult, but one possibility involved a truck parked near the hotel.
"A large vehicle parked in our alley for too long," said Lana Wyke, the front desk manager at the hotel. "The vehicle was running, and firefighters said our exhaust system could have brought the carbon monoxide down into our laundry area."
According to Marriott general manager Jennifer Anderson, 120 of the Marriott's 128 rooms were occupied. Due to the inclement weather, all of the evacuees were directed to the Residence Inn by Marriott, which is a short distance down the street.
Chattanooga firefighters worked quickly to evacuate the seven-story building.
"It was kind of chaotic," said Ms. Wyke. "Everyone inside was evacuated and out for four hours."
Other employees with special equipment were dispatched to assist with the investigation.
"While the evacuation progressed, the (hazardous materials) team was called in to help determine what made the employees sick," Mr. Garner said. "Haz-mat technicians used sensitive monitoring devices to determine that the air had dangerous levels of carbon monoxide, especially in the laundry room area of the basement."
The firefighters used high-powered fans to ventilate the entire building until no levels of carbon monoxide were detected. The Marriott staff were allowed back in first, and around 1:30 p.m. the residents were allowed in.
Chief Hague said technicians with the Chattanooga Gas Co. and Moccasin Bend Wastewater Treatment Plant were asked to assist with the investigation in determining possible sources for the carbon monoxide. That investigation will be ongoing.
"It really was a freak thing," Ms. Wyke said. "I guess we're going to have to monitor the driveway beside us where the truck was parked too long and running. It really is scary."
Capt. Batson said one of the victims is pregnant. No additional information is available on their conditions, Mr. Garner said.