HIGHWOOD, Ill. (CBS) — Four people were rushed to the hospital Monday after a north suburban dentist turned on the furnace in his office for the first time this season.

Officials say the four were overcome by fumes from carbon monoxide in the building on Green Bay Road in Highwood. And as CBS 2’s Kristyn Hartman explains, it could have been a lot worse if firefighters didn’t have a carbon monoxide alarm with them.

Highwood firefighters raced to two calls minutes apart from the same building — one for chest pains, the other for possible stroke.

Crews took their “first in” bag, which has everything they need to get treatment started. Battalion Chief Dave Mohry says one of the items in the bag, a carbon monoxide monitor, blared just moments after first-responders got on the property.

The reading they got was for 1,000 parts per million. A reading of 30 parts per million is considered dangerous, Mohry said.

Things could have been worse. If the first-responders didn’t have that device to warn them, they might have tried to stabilize the patients inside the building and could have succumbed to the gas as well.

One of the first-responders said he got a headache just from the short amount of time he was in the building.

Mohry says the incident is a timely reminder as people begin turning on their furnaces.

“Spend the extra money and go get yourself a CO monitor,” he said.

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