CHICAGO (CBS) — The Fire Department was warning Chicago residents not to use gasoline-powered machines indoors, after responding to a potentially deadly carbon monoxide leak in the Chatham neighborhood.

Crews responded to a carbon monoxide leak at 8048 S. Champlain Av. Tuesday morning, after someone at the home had been using a power washer in the basement.

The emissions from the gas-powered washer caused carbon monoxide levels inside to reach 1,000 parts per million (ppm), which is enough to kill within minutes, according to the Fire Department. The building had carbon monoxide detectors, as required by law, and someone called 911 before it was too late.

Even with open doors and windows, gasoline powered machines should never be used inside. The units should only be operated outdoors.

According to the U.S. Consumer Product Safety Commission, while most people won’t suffer any side-effects from prolonged exposure to CO levels of 1 to 70 ppm, some heart patients might suffer chest pain. At levels higher than 70 ppm, prolonged exposure can cause headaches, fatigue, and nausea. At concentrations higher than 150 to 200 ppm, exposure can cause disorientation, unconsciousness, and death.

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