CLAY TWP — A scary situation Monday night at a house in the township serves as a reminder for homeowners to have working carbon monoxide detectors, the West Sunbury fire chief said.

Butler Ambulance Service was dispatched to a one-story house where a man and woman were reportedly ill, said Matt Wilson of the West Sunbury Volunteer Fire Department.

Paramedics requested the fire department respond to check the house for carbon monoxide levels. Firefighters, wearing breathing devices, entered the house and used hand-held meters to test the air. They recorded a reading of 647 parts per million.

“That's the highest amount we've ever seen,” Wilson said.

In firefighter training, they learn that as little as 9 ppm in a home can cause symptoms, he said.

The typical CO level in a home with a properly adjusted gas stove ranges from 5 to 15 ppm, according to the U.S. Environmental Protection Agency.

The EPA describes CO as odorless, colorless and toxic gas on its website.

“Because it is impossible to see, taste or smell the toxic fumes, CO can kill you before you are aware it is in your home,” according to the EPA.

Symptoms of carbon monoxide poisoning can include fatigue, chest pain, headaches, dizziness, confusion and nausea.

The Occupational Safety and Health Administration limits exposure of CO in a workplace to a maximum of 50 ppm over an eight-hour period.

Any open flame, including a pilot light on a water heater or furnace, puts out some amount of carbon monoxide. It can also come from fireplaces, automobile exhaust and tobacco smoke, according to the EPA. A level of 647 ppm is not only extremely hazardous to breathe, but there is risk of explosion too, Wilson said.

Firefighters suspect the cause of the CO Monday was a coal-burning furnace that was not properly vented and a portable propane heater that was not venting to the exterior of the house, he said.

The house also had a propane fireplace and an electric furnace.

Firefighters quickly opened all the windows and turned off all appliances that produce a flame.

They then safely removed the burning coal from the furnace and kept monitoring the CO levels until they reached zero.

Unionville Volunteer Fire Company members assisted by lending several breathing apparatuses and setting up a landing zone at its station in Center Township.

The female patient, who the fire department did not identify, was flown in a Stat MedEvac helicopter to Allegheny General Hospital in Pittsburgh. Her condition was not known Tuesday. The man was taken by ambulance to Butler Memorial Hospital and was treated and released Monday night, Wilson said.

He said the homeowners were advised to only use their electric furnace until a professional could come and evaluate the other heaters and ensure that the home is safe.

The home did not have a functioning CO detector. Every homeowner and renter should have a CO detector, with a battery backup if it is plugged in the wall, and make sure to routinely check to make sure it is functioning, Wilson said.

“A CO detector is just as important as a smoke detector, especially if you have something with an open flame,” Wilson said. “This stuff can kill you.”