Indoor air contaminants can originate within the building or be drawn in from outdoors. If contaminant sources are not controlled, IAQ problems can arise, even if the HVAC system is properly designed and well-maintained.

Sources Outside Building

Contaminated outdoor air

  • pollen, dust, fungal spores;
  • industrial pollutants;
  • general vehicle exhaust .

Emissions from nearby sources

  • exhaust from vehicles on nearby roads or in parking lots, or garages;
  • loading docks;
  • odours from dumpsters;
  • re-entrained (drawn back into the building) exhaust from the building itself or from neighboring buildings; and
  • unsanitary debris near the outdoor air intake

Moisture or standing water promoting excess microbial growth

  • rooftops after rainfall
  • crawlspace

Other Sources

Accidental events

  • spills of water or other liquids
  • microbiological growth due to flooding or to leaks from roofs, piping
  • fire damage (soot, PCBs from electrical equipment, odors)

Special use areas and mixed use buildings

  • smoking lounges
  • laboratories
  • print shops, art rooms
  • exercise rooms
  • beauty salons
  • food preparation areas

Redecorating/remodeling/repair activities

  • emissions from new furnishings
  • dust and fibers from demolition
  • odors and volatile organic and inorganic compounds from paint, adhesives
  • microbiologicals released from demolition or remodeling activities