Building ventilation is the circulation of air throughout a building. The ventilation or the heating, ventilating, and air-conditioning (HVAC) system of a building supplies and removes air either naturally (windows) and/or mechanically to and from a space. HVAC systems consist of mechanical parts which should provide air to building occupants at a comfortable temperature and humidity that is free of harmful concentrations of air pollutants. Building ventilation may be an important factor determining the relationship between airborne transmission of respiratory infections and the health and productivity of workers.

Why is the operation and maintenance of HVAC systems important?

Improper operation and maintenance of HVAC systems is one of the most common problems that impact workplace indoor environmental quality (IEQ).  HVAC systems include all of the equipment used to ventilate, heat, and cool the building; to move the air around the building (ductwork); and to filter and clean the air. These systems can have a significant impact on how pollutants are distributed and removed.  Maintaining good IEQ requires constant attention to the building's HVAC system, which includes the design, layout and pollutant source management or air filtration. 

There are a variety of pollutants and sources of pollutants in a building such as:

  • carbon dioxide (CO2)
  • tobacco smoke
  • molds and bacteria
  • cleaning products
  • copy machines
  • pesticides
  • vehicle exhaust

dust, pollen and bacteria affects air quality

HVAC systems alone can act as sources of pollutants. If not appropriately maintained, ventilation air filters can become contaminated with dirt and/or moisture. Microbial growth results from stagnant water in drain pans or from uncontrolled moisture inside of air ducts and cooling coils.

Outdoor Air Quality
When present, outdoor air pollutants such as carbon monoxide, pollen, and dust may affect indoor conditions when outdoor air is taken into the building's ventilation system. It is important to properly install and maintain HVAC system filters, which can trap many particles. Controlling gaseous or chemical pollutants may require more specialized filtration equipment and sometimes relocation of the outdoor air intakes.

Useful Information:

Health Canada Information on Indoor Air Quality
Environmental Protection Act - US Indoor Air Quality
USEPA Information on Indoor Air Quality
US Department of Health Indoor Air Pollution
National Air Duct Cleaners Association General Information
OSHA on Indoor Air Quality Indoor Air Quality