Rochester, MN – A Rochester family has been displaced from its home, and fire department officials are looking at construction in the area as a possible cause.

First responders were called about 12:25 a.m. today to the 4200 block of Dodge Lane Northeast, where they found elevated levels of carbon monoxide — 100-150 parts per million — in the house.

Firefighters went through the home looking for a source, said Larry Mueller, assistant fire marshal for the Rochester Fire Department. The appliances were all fine, he said, but the sump pump appeared to be the source. The pump was disassembled and the area was covered with plastic.

Construction crews are blasting land in the area, officials learned, possible sending the odorless, colorless gas through the ground into the home.

About 6:25 a.m., firefighters responded again to the home for a carbon monoxide alarm. This time, Mueller said, there were about 50 ppm of the gas throughout the home.

Officials checked two additional homes in the area to measure for the presence of the deadly gas, but detected none, he said.

The homeowners have been advised to leave the home and stay away until a source is confirmed and the levels have dissipated.

Mueller said they’ll discuss the situation with the construction crews.

“We sometimes see other gases, like methane, come through as a result of blasting, but we’ve never seen carbon monoxide like this,” he said.

The health effects of CO depend on the concentration and length of exposure, as well as each individual’s health condition. Most people will not experience any symptoms from prolonged exposure to CO levels of approximately 1 to 70 ppm, but some heart patients might experience an increase in chest pain.

As CO levels increase and remain above 70 ppm, symptoms become more noticeable and can include headache, fatigue and nausea. At sustained CO concentrations above 150 to 200 ppm, disorientation, unconsciousness and death are possible.