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Understanding Indoor Environmental Quality

Indoor environmental quality (IEQ) is an important factor for building occupants’ health and the owner’s bottom line. A proactive approach to IEQ can be good for people and business.

A woman stands at a window with reflected greenery.

October 20, 2020

By some estimates, humans spend up to 90% of their time in homes, schools and offices.1 The quality of the interior environment, also known as indoor environmental quality or IEQ, encourages the health and wellness of occupants, and may function as a potential business benefit. Most simply described as the conditions inside a building, IEQ refers to the quality of a building’s environment in relation to the health and well-being of its occupants. The topic of IEQ includes air quality but also includes such issues as access to daylight and thermal comforts. 

For building managers and owners looking to attract and retain tenants, developing a proactive IEQ policy may be an important tool to consider. A recent study2 found that improvements in health and well-being due to a move to a greener building lead to significantly enhanced job satisfaction and a 2% reduction in the prevalence of sick leave for a group of municipal workers in Amsterdam. The study authors, from Maastricht University, estimate this reduced absenteeism saved the municipality more than $30,000 per year. 

Now more than ever, people are searching for peace of mind regarding building spaces. Addressing IEQ with a comprehensive, proactive approach can be good for health and good for business. 

Impact of IEQ on human health

The quality of IEQ plays an increasingly important role in overall human health and wellness. A range of key physical factors in indoor environments can have an impact on health and wellness.

Air quality 

Construction methods designed to increase a building’s energy efficiency can also reduce the circulation of outside air. As a result, emissions from building construction materials and furnishings can linger in the air for longer periods of time, leading to elevated levels of volatile organic compounds (VOCs) and other common pollutants, and increases in certain health-related effects, such as asthma, eye, nose and throat irritation, allergic skin reactions, headaches, dizziness and fatigue. VOC emissions from furnishings, textiles or paneling can reach many times the concentration in enclosed areas than in open areas. 


Water is crucial to human life, so appropriate IEQ requires access to clean water for drinking and cleaning. Water that is contaminated by microbes, lead from pipes or other chemicals can cause serious illness or injury. Older buildings or those connected to older municipal water sources are at greater risk for pipe-related contamination. 


Regular exposure to natural light promotes both good physical health and emotional well-being. However, most modern buildings primarily rely on artificial light to illuminate interior workspaces, utilizing lamps and luminaires based of light emitting diode (LED) technology. Although LED lighting is more energy-efficient than fluorescent or incandescent lighting, prolonged exposure to the optical radiation and other photobiological effects produced by LEDs can lead to irritation of the eye and the retina. 


The acoustics of a building are important to encourage concentration and reduce distraction. Three common acoustic complaints are noise from outside the building, such as from road or air traffic, noise from adjacent spaces, and noise within a space. A space with good acoustic control also minimizes echoes, often through sound-absorbing materials.

Thermal comfort 

Thermal comfort, including appropriate temperature and humidity levels, is essential for worker comfort and productivity. At the same time, although there is no single indoor temperature that ensures thermal comfort for everyone, many modern buildings provide little individual control over temperatures in specific locations. As a result, occupants often feel either too warm, making them prematurely tired, or too cold (which can make them distracted and unable to focus their attention). 

Interior layout and furnishings 

Many interior workspace designs and arrangements are focused on promoting occupant interaction and engagement with others. But the widespread use of open space arrangements can also increase environmental noise and decrease the ability of occupants to concentrate when necessary. Further, individual workspace furnishings, such as desks, chairs and fixtures, often do not address important ergonomic considerations and fail to optimize occupant physical comfort throughout the workday. Not only do these and other factors have a direct impact on occupant health and wellness, they can also contribute to decreased levels of productivity and higher rates of absenteeism and presenteeism. They may also lead to reduced levels of occupant engagement and satisfaction, resulting in higher employee turnover, increased labor and benefits expenditures for employers.

Impact on employee retention

Building owners and operators recognize the importance of providing buildings that are safe and healthy for occupants. Studies have shown that poor IEQ can affect cognitive functions like problem solving and decision making.3 A study found that more than two-thirds of employees said a workplace that supported healthy and safety would encourage them to accept a job offer, or to stay at their current jobs,4 which can save companies on turnover costs. The Center for American Progress estimated that employee turnover can cost up to 20% of that employee’s annual salary after recruiting and training a new employee is factored in.5 Creating a healthier building can attract and retain tenants and employees, reduce turnover costs and help organizations better position themselves to become sustainability leaders in the marketplace. 

Since the passage of the U.S. Occupational Safety and Health Act in 1970, the incidences of workplace-related injuries and illnesses in the U.S. have declined by as much at 67%.6 Improved workplace safety practices, combined with widespread access to employer-sponsored healthcare insurance and wellness programs, have contributed to a safer and healthier workforce, and have helped companies increase overall productivity to historically high levels.7 As a result, most knowledgeable employers understand the direct link between employee health and their company’s success and profitability, and remain committed to company programs that support employee health and well-being.

Addressing physical building issues

In addition to monitoring the human factors addressed in the previous section, certain physical issues with the building can have a grave effect on IEQ. The business owner or manager has an obligation to address these promptly.  

Water systems and damages

Potable cold and hot water systems need to be flushed regularly and tested for quality. Hot water temperatures should be sampled at the point of use. Further, the quality of potable water should be tested, confirming its suitability. Some test methods may include microbial analysis, ion chromatography, mass spectroscopy and titration.

Legionella bacteria, the cause of Legionnaires’ disease, can grow and spread in a building’s water system, creating health risks to building tenants. Water treatment of utility and potable water assets may not be enough for risk management. Building owners and managers must maintain their building’s water systems in compliance with ASHRAE 188 to reduce the health risk of Legionella. 

Leaks and hygiene issues surrounding sinks, showers, toilets, kitchens, fountains, water coolers, refrigerators, janitor’s closets, accessible pipe chases and decorative indoor plant containers can all cause issues. These areas can all harbor mold or develop fungal issues. Outside water may leak through walls, windows, vents and roof membranes without notice, so they must be checked to reduce mold and building damage. 

Many long-term problems manifest themselves weeks, months or years after the water damage. At the top of the list of future problems are those due to the pervasive molds. Mold can happen anywhere. Fungi are prevalent throughout nature and thrive in humid environments. Mold growth can be dangerous for anyone with asthma, chronic obstructive pulmonary disease, allergies or other respiratory issues. NIOSH research studies have shown that exposures to building dampness and mold have been associated with respiratory symptoms, asthma, hypersensitivity pneumonitis, rhinosinusitis, bronchitis and respiratory infections. The U.S. Occupational Safety and Health Administration has limited specific standards referring to mold so the general duty clause applies in most cases. The U.S. Environmental Protection Agency does not have federal regulations or standards for airborne mold contaminants. Building owners may want to perform a visual and infrared inspection of representative available surfaces for leaks/mold (ventilation, filtration and hygiene).

Air quality

VOCs are chemicals emitted from a wide array of products, from paints to carpets. These compounds may contain a variety of chemicals that can cause illness or injury. Building owners should take care to store products properly, chose lower VOC-producing fabrics for building and flooring materials and office furniture, and properly ventilate when painting or using other organic solvents.  

Asbestos, while usually a problem in older buildings or during construction, has never been completely banned from import or installation. Asbestos is a known health hazard that can cause severe lung diseases including pulmonary fibrosis and mesothelioma. Federal, state and local regulators require owners and operators to conduct surveys for asbestos-containing materials prior to major retrofits or demolition. 

Facility sanitization helps prevent the spread of illnesses. When approved sanitizers run low, however, some people turn to chlorine sanitizing agents such as unscented bleach. Bleach can be a highly effective sanitizer, but it can also be potentially hazardous when misused: specifically, when mixed with other cleaning products that contain ammonia, it creates a highly toxic chlorine gas. The cleaning staff needs proper training on how to mix and use cleaning solutions, use the appropriate personal protective equipment (PPE), such as wearing gloves or a protective outer garment, and to provide appropriate ventilation in rooms where sanitizers are mixed and stored.

If the building requires additional air capacity, increasing airflow can affect the efficacy of opening and closing fire doors. Increasing air movement will pressurize corridors and stairs, potentially putting a building in violation of the life safety code of the National Fire Protection Association (NFPA). A trained fire expert needs to test fire protection systems for adjustment any heating, ventilation or air conditioning (HVAC) levels, added different types of filters or closed off vents.

Why develop a proactive IEQ policy?

A proactive approach to IEQ is not only the right thing to do, it can be the profitable thing to do. A comprehensive record of anticipating IEQ issues can be used as a marketing tool to attract new tenants where the real estate market is competitive. For existing tenants, it can enhance relationships by demonstrating a genuine concern for the tenants and their employees. Less time may be needed to investigate and resolve complaints.
Proactive IEQ programs can also help demonstrate due diligence. Building owners and managers who manage what they measure may have lower exposure to risk than those who address issues only when they arise.  

Additionally, owners with large building portfolios benefit from proactive IEQ to demonstrate maintenance standards and support engineering or operation budgets. A cohesive, organized and coordinated IEQ policy may help provide critical documentation for certification credits.

Finally, proactive IEQ monitoring can document improvements made over time. This results in a smoother due diligence process at sale. The cost of addressing IEQ is more than recovered at sale time when the documents demonstrate a high and improving standard of IEQ over the seller’s hold time.

Developing and implementing a proactive IEQ program can be a smart investment for health and business value. If you are interested in learning more about how UL’s building services can help, please contact us.


  1. “The Inside Story: A Guide to Indoor Air Quality,” the U.S. Environmental Protection Agency, updated February 16, 2018. Web. 10 April 2018.
  2. Juan Palacios et al. (August 2020), Moving to productivity: The benefits of healthy buildings. 
  3. Veronique Greenwood (May 2019), Is Conference Room Air Making You Dumber? 
  4. Jeanne Meister (August 2019), Future Workplace Study: Natural Light and Air Quality Have the Biggest Impact on Workplace Wellness.   
  5. Heather Boushey and Sarah Jane Glynn (November 2012), There Are Significant Business Costs to Replacing Employees
  6. “Commonly Used Statistics,” U.S. Department of Labor, Occupational Safety and Health Administration. Web. 18 August 2015. 
  7. See, for example, “GDP per hour worked” data collected by the Organisation for Economic Co-operation and Development (OECD). Web. 18 August 2015. 

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