First responders are reminding the public to have their furnaces checked and make sure their carbon monoxide detectors are working following a medical call Monday morning,

According to Austin Police Capt. David McKichan, a medical call was made at about 4:30 a.m. on Monday after a woman in a northwest Austin residence had fallen and was complaining of weakness. A Gold Cross Ambulance crew had a CO detector that went off when they arrived. The Austin Fire Department arrived on the scene and confirmed the presence of CO.

It was determined the CO was residual, caused by a pressure washer that had been run in the house, according to McKichan.

“Now that it’s getting cold, make sure you check your furnaces and CO detectors,” McKichan said. “CO can overwhelm you if you don’t know it’s there.”

McKichan also recommended family members knowing the difference between the sound of a smoke detector and a CO detector. He also said to call 911 if a CO detector is activated.