Air Flow

• Without air flow, the liquids inside plumbing pipes won't move as freely. Air helps push waste down through pipes and out into the drainage system. Air in empty pipes floats naturally up the vent to be released through the roof. With no air in the pipes, the water will not flow and debris may become dislodged in pipes to create clogs.
  
  

Gasses

• Plumbing vents help eliminate sewer gas odors that emanate from plumbing pipes. Traps prevent the gasses from leaking into your drains; venting pipes carry those odors away and release them through the roof. Sewer gasses aren't just unpleasant in smell; they're dangerous because they contain methane gas. Inhalation of sewer gasses may even be fatal.
  
  

Clogs in Vents

• Vent plumbing pipes may become clogged like any other plumbing pipe. Nests built by wasps, birds and other wildlife may obstruct a vent pipe and prevent airflow. Small, water-loving animals like frogs may even take up residence in a vent pipe and restrict air. Ice is a common vent pipe enemy in northern regions with cold winters. Cold temperatures may freeze moisture and condensation around the pipe. Snow may also pile up around vent pipes to block air flow. Clogs must be removed from vent pipes for air to flow properly.
  
  

Maintenance

• Regular maintenance keeps plumbing vent pipes functioning properly. Check pipes for clogs in winter or any time you notice sewer gas smells inside your home. A clogged vent pipe may cause drains to back up. If you notice excessive sewer smells, call a plumber to check for misplaced or damaged plumbing vent pipes.