The Bradenville fire chief gave a warning about chimney and furnace safety after two apartment tenants in Derry Township were overcome by carbon monoxide poisoning Wednesday night.

Chief Mark Piantine said a tenant at the School Street apartment building who felt ill contacted him just before 8 p.m. He declined to identify the tenant.

Piantine said the main furnace at the building had been started Wednesday.

“The chimney was plugged up, and it filled the whole place with carbon monoxide,” he said Thursday morning.

Carbon monoxide levels on the first floor were over 1,200 parts per million, Piantine said.

“That will kill you,” he said.

Two second-floor residents escaped the building and were treated at Excela Latrobe Hospital and released, Piantine said.

When Piantine arrived at the apartment, he opened several windows on the first floor, which is being renovated, he said. When smoke rolled out, he called in an alarm.

“We had to force our way into the basement, where the furnace was. We shut the furnace down and started ventilating,” he said.

A carbon monoxide detector on the first floor was going off when he entered, but it could not be heard upstairs, he said.

“They (detectors) are up there now,” he said.

The upstairs apartments sustained soot damage and will have to be cleaned.

Carbon monoxide is a deadly, colorless, odorless, poisonous gas, according to the Consumer Product Safety Commission. It is produced by the incomplete burning of fuels, including coal, wood, charcoal, oil, kerosene, propane and natural gas.

Symptoms of carbon monoxide poisoning include headache, fatigue, shortness of breath, nausea and dizziness.

According to the Centers for Disease Control and Prevention, carbon monoxide poisoning is responsible for about 15,000 emergency department visits and nearly 500 deaths annually in the United States.

Piantine said this weekend's switch to daylight saving time is a good time to prepare for winter by getting chimneys cleaned and furnaces inspected. Carbon monoxide detectors should be checked to make sure they have working batteries, he said.

Firefighters from Derry, Latrobe and Ligonier assisted at the scene.

Mary Pickels is a staff writer for Trib Total Media. She can be reached at 724-836-5401 or mpickels@tribweb.com.