South Metro Fire Rescue Authority is warning residents to clear the snow from the vents outside their homes.
Firefighters said they are seeing an increase in calls for the smell of natural gas.
That may be because snow drifts outside many homes are covering the exhaust vents.
South Metro Fire Rescue recommends you walk around your home and find the exhaust vents, likely just five to six inches above ground, and clear the snow around them.
They also recommend buying a carbon monoxide detector to monitor levels inside your home.