Carbon monoxide levels of over 600 parts per million (ppm) were detected Oct. 29 in a home at 1021 Water Ave.

Levels between 200-800 ppm will produce dizziness, drowsiness and vomiting in as little as one hour, and can endanger lives within three hours.

Hillsboro Fire Chief Thomas Sebranek called Alliant Energy and other members of his department for assistance.

Firefighters forced fresh air into the house using ventilation fans, while Kent Thurston of Alliant shut off the house’s natural gas supply. Its residents were told to find alternative lodging for the night.