Allentown, PA – It’s called the silent killer for a reason.

An Allentown family narrowly escaped their home on Liberty Street after it filled with carbon monoxide overnight, officials said.

The family is fine, but what happened to them is a powerful reminder of why every home should have a carbon monoxide detector.

“They woke up. Everyone was exhibiting flu-like symptoms, headache, nausea, so they took themselves to the hospital, and the hospital found out they had high levels of carbon monoxide in their system,” said Capt. John Christopher, Allentown Fire Dept.

Fire officials measured the levels inside the home and got a reading of 1,000 parts per million, more than enough to be deadly. The cause was attributed to a crack in the furnace heat exchanger.

The home didn’t have carbon monoxide detectors, but people living in Allentown can now get one for free. All they have to do is contact the Allentown Fire Department at 610-437-7765 and show proof of residency.

Once you get it, pop some batteries in and place it in a central location, perhaps the foyer or a bedroom hallway.

Carbon monoxide can come from a variety of sources, including a blocked chimney or furnace, attached garage, clothes dryer, portable heater, water heater, range hood or indoor grill.

Just because you don’t have these things doesn’t mean you can’t be exposed, said fire officials. If you are attached to another home, carbon monoxide could spill into your home while you sleep.

“It’s colorless. It’s odorless. It’s tasteless. You are not going to notice. The only way you are going to be alerted to it is with a detector,” said Christopher.