Two construction workers lost consciousness after carbon monoxide fumes reached nearly fatal levels at a Wilson Ridge residence.

Fire Marshal Bob Buch said Noroton Heights, Noroton and Darien fire departments responded to 20 Wilson Ridge at 10 a.m. after two construction workers were dragged from the home after losing consciousness because of high levels of carbon monoxide.

"The workers were in the basement using a gas-powered wet saw to cut the cement to install some drain pipes," he said. "There was no ventilation in the room and the only opening was closed off with a tarp."

The carbon monoxide levels reached 700 parts per million and levels that high are fatal, Buch said. A carbon monoxide detector will be set off when levels reach 35 parts per million. Buch said levels of carbon monoxide between 35 and 200 parts per million will result in flu-like symptoms including nausea, drowsiness and dizziness. Higher concentrations of carbon monoxide can be fatal if left untreated.

"Someone found both workers unconscious and dragged them out of the house," Buch said. "They were transported to the hospital and both were conscious at the time they were transported. An infant in the home was also transported to the hospital as a precaution."

Buch said it was fortunate more people weren't affected by the fumes because the house was full of workers doing other renovations.

As a precaution to avoid a similar incident, Buch said gas-powered tools should never be operated in an area that isn't well ventilated. Any carbon monoxide detectors should be tested every month to make sure they are functioning properly.