If snow blocks sewer vent pipes, sewer gas can seep into the house and make the occupants ill. Symptoms such as headaches, dizziness and nausea may be signs of exposure to an odorless sewer gas. Sometimes a smell like rotten eggs in the home also indicates a clogged vent pipe.
Vents must be cleared during the winter to prevent sewer gas from coming into the home. Having a professional install a heat register in the attic may melt the snow and keep the pipes clear. Wrapping the vent with an insulating sleeve or a batting of fiberglass insulation can also keep snow from clogging the pipes.