Indoor Environmental Quality

Banner image: mold, vent, construction workers, hands cleaning a counter top


Indoor environmental quality (IEQ) refers to the quality of a building’s environment related to the health of occupants within it. IEQ is determined by many factors, including lighting, air quality, and damp conditions. Workers are often concerned that they have symptoms or illnesses caused by exposures from the buildings where they work. One reason for this is because their symptoms often get better when they are not in the building.

Research has shown that some respiratory symptoms and illnesses can be associated with damp buildings. It is unclear what levels of indoor contaminants show that workers are at risk for disease. Determining which contaminants are responsible for suspected building-related conditions can be challenging. Many times the results of medical tests and environmental tests are not sufficient.

Despite uncertainty about what to measure and how to interpret what is measured, research shows that building-related symptoms are associated with building characteristics. These characteristics include:

  • Dampness
  • Cleanliness
  • Ventilation

Indoor environments are highly complex. Building occupants may be exposed to a variety of contaminants in the form of gases and particles that include:

  • Office machines
  • Cleaning products
  • Water-damaged building material
  • Microbial growth (fungal, mold, and bacterial)
  • Insects
  • Carpets and furnishings
  • Perfumes

Additional contaminants include cigarette smoke, construction activities, and outdoor pollutants. Indoor temperatures, relative humidity, and ventilation levels can also affect how individuals respond to the indoor environment.

Understanding the sources of indoor environmental contaminants and controlling them can help prevent or resolve building-related symptoms in workers. Practical guidance for improving and maintaining the indoor environment is available.

Workers with persistent or worsening symptoms should seek a medical evaluation for diagnosis and treatment.

Page last reviewed: May 17, 2013