As environmental consultants, it’s our mission to be a reliable source of information. From questions about specific remediation solutions to what to expect after submitting a consultation request, we answer frequently asked questions. 

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What is a sick building?

The cause of occupant illness in buildings is frequently multi-factorial and difficult to quantify. For example, buildings degrade over time when improperly maintained; or the use of the building may change due to tenant requirements or other factors related to its purpose or operation. These types of variables can have cumulative negative impacts on the quality of the building’s indoor environment which may result in health-related symptoms and issues for its occupants.

Factors that may contribute to discomfort for building occupants include:

  • modern office equipment
  • furnishings
  • interior finishes
  • ventilation settings
  • HVAC performance
  • outdoor air pollution
  • energy-efficiency of building materials
  • energy-saving operational procedures
In most cases, when a sick building is identified and remediation efforts begin, symptoms dissipate within a relatively short period.  

What is sick building syndrome (SBS)?

A term sometimes used to describe conditions when occupants experience acute health or comfort effects that appear to be linked to time spent indoors in a particular building. Complaints may be localized to a time of day, a specific location within a building, or the entire building. Typically, the symptoms reported by occupants are non-specific (e.g. headaches, fatigue, congestion, etc.). As a result, it makes diagnosis difficult without a concomitant investigation. Symptoms may be rooted in factors such as physical comfort, microorganisms, chemicals, pathogens, or psychological mechanisms. When occupants leave the building, symptoms generally dissipate. Furthermore, as the case may often be multifactorial, so likewise is the solution.

When is a building labeled as having a building related illness (BRI)?

Diagnosable illnesses in occupants whose symptoms can be identified and whose cause can be directly attributed to a building. In contrast to “sick buildings”, when affected occupants leave the building, their symptoms typically do not dissipate. For example, if a building has water damage that was ineffectively cleaned up and a person in that building develops a respiratory infection, then it is a BRI. Another example would be if there was an exposure to a regulated hazard that resulted in a medially diagnosed illness such as Legionnaires’ Disease which develops from a contaminated indoor water source.

Why do newer buildings seem to have more IAQ problems than older ones?

While this is not necessarily true, newer buildings (post-1970s) are built with energy conservation in mind. There are many ways to minimize energy costs due to cooling and heating losses, however, one common way is reducing the outdoor air ventilation and the leakage factor. As a result of better construction and insulation techniques, this action, in effect, makes buildings tighter and better sealed against natural air exchanges between indoor and outdoor air through the process known as infiltration. Additionally, some buildings practice reduced outdoor air ventilation policies during the hot cooling season. These conditions and more may collectively work to reduce the dilution of indoor air from infiltration (that older buildings may have) allowing concentrations of indoor contaminants and odors to increase. Normal sources of indoor contaminants include office equipment, furnishings, new construction materials, occupants, processes, etc.

Is there a routine recommended IAQ test?

No. There is no routine “litmus” test for good/bad IAQ in environments where there is no known specific “panel” of contaminants. This is due to the diversity of possible contaminants and the fact that analysis of individual contaminants in air samples may not reveal significant concentrations while combinations of several contaminants or conditions may have adverse effects. For these reasons, the preferential method of approaching any IAQ investigation where the symptoms are non-specific and potentially related contaminants are unknown is to perform an initial observational site survey. Similar to when people initially go to the doctor when sick, the purpose of this survey is to develop an initial hypothesis and recommendations.

I’ve heard about a CO2 test, but what is it for?

Carbon dioxide (CO2) is a normal product of human respiration that is present in atmospheric gas. It is used as a surrogate ventilation indicator, primarily for odor control. People’s normal breathing activities add small amounts of CO2 to the indoor air. In the mid-1900s, before buildings were mechanically ventilated and furnished with offices and computers, studies demonstrated that when the buildings were filled with people, CO2 levels increased. Likewise, body odor also increased. Furthermore, they recognized that if the fragrant-rich indoor air was diluted with outdoor air, the air quality improved. In fact, both the odors and CO2 levels decreased. This understanding led to ventilation standards known as the standard minimum of Outdoor Air ( OA). These standards were further enhanced as buildings became more energy efficient and introduced more products and materials with VOCs. Essentially, the more OA is introduced, the fewer chemicals and odors are detected. Additionally, using conditioned, filtered, and acceptable OA, other contaminants that may be present indoors are also diluted. Still, today, using COas a screening tool for ventilation effectiveness provides useful insight into how the building’s environment controls other potential contaminants.



My CO2 levels go above 1000 ppm which means people will start getting sick, right?

Wrong. The 1000 ppm level is not a health exposure limit. It was an old dilution ventilation target based on a specific occupancy level and type of activity in commercial buildings. There are no documented adverse health effects to people exposed to COlevels under 5000 ppm. The 1000 ppm indoor maximum level was previously recommended by ASHRAE for indoor office spaces to provide ventilation for acceptable indoor air quality (comfort as opposed to health). Newer versions of ASHRAE standards for ventilation recommend a variation. Also, local building codes often supersede guidelines. Conversely, COlevels below 1000 ppm may not accurately indicate acceptable indoor air quality if there are contaminants present in the space at levels that may adversely affect occupants.

How do I know if my air ducts need cleaning?

Most modern buildings contain mechanical heating, ventilating, and air conditioning systems (HVAC). These systems include a variety of components such as fans, temperature-modifying coils, air filters, and ductwork which work to distribute air. HVAC systems degrade over time and require regular cleaning and maintenance. If an inspection by a qualified duct cleaner identifies any of the following, then they may recommend cleaning the building’s air ducts:

  • an accumulation of particles
  • compromised performance due to particulate
  • odor terminating from the HVAC system
  • visible discharge of debris into the environment
  • fire, smoke, or water damage
  • rodent (such as birds, mice, or insects) infestation and/or their byproducts
  • risk of a fire hazard
  • contamination from construction debris
  • mold growth or related damage
  • deterioration

The US EPA (Environmental Protection Agency) cautions homeowners about having duct cleaning done without first becoming educated about the benefits or needs. To get started, reference this useful Duct Cleaning Guide.

To inquire about a proper HVAC cleanliness inspection, contact a duct cleaner who is accredited by the National Air Duct Cleaners Association (NADCA) and who follows the NADCA Standard Assessment, Cleaning, and Restoration of HVAC Systems (ACR).



Can you test my indoor air quality? Is my air quality good or bad?

Unfortunately, there is not a “silver bullet” test to qualify and quantify all the contaminants of indoor air. Testing is specific to the type of contaminant suspected in the space. Furthermore, a sample strategy is not typically designed until after information has been gathered regarding conditions near the site, processes occurring in the space, possible environmental influences, etc.

I have an odor in my house, what is it?

Odor diagnostics involves much more than performing a single test. Due to personal and environmental factors, odor perception and intensity usually vary from person to person. Before any testing, information must be gathered on probable or possible odor sources. Even if a sample strategy is implemented, the sensitivity of the human nose makes odor detection possible for humans at concentrations well below those of most test instruments. Keep in mind that when there are indoor contaminants, it may be the case that humans detect the contaminant’s odor however, humans are unable to measure by odor magnitude to determine whether there is a health concern or not.

There are black particles deposited on supply air diffusers – what is it and is it harmful?

These black particles are typically from normal airborne particulates (e.g. carbon black and dust) found in room air, which, when entrained into the discharge air from the diffusers, impinges upon the diffuser. Also keep in mind that if you can see the particles, they are too large to be respired down into the lungs – rather, they will become lodged in the nasal passages of the upper respiratory system.

I experience allergic symptoms when in my home. Can you test for molds and mildew?

Moist (wet) materials provide a thriving environment for microbial growth and can act as reservoirs even after the water source is no longer active. If you’ve had water damage, then it is often the case that the most cost-effective solution is to remove and replace all damaged materials. Testing may not be necessary at this point, especially if you are noticing allergy symptoms that were not present before the water damage. In the instance that you are unaware of water damage or cannot detect any issues, it may be helpful to contact an indoor environmental specialist to inspect and test your home for contaminants.

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