The Impact of Poor Indoor Air Quality in Multifamily Buildings

by Craig Kuski |

According to the United States Environmental Protection Agency (EPA), the concentration of some pollutants is often 2 to 5 times higher indoors than outdoors. The average American spends approximately 90% of their time indoors, so indoor air quality (IAQ) is extremely important to everyone’s health. As a building owner, proper ventilation will not only increase tenant satisfaction, it will help protect your investment by mitigating mold, mildew and other negative outcomes of poor indoor air quality.

Pollutants Lurking in Buildings

A major factor in the need for improved IAQ is the increased awareness on the dangers of volatile organic compounds (VOCs).

 Common household chemicals are a source of VOCs in buildings.

The EPA defines Volatile Organic Compounds (VOCs) as gasses emitted from certain solids or liquids. VOCs include a variety of chemicals, some of which may have short-and long-term adverse health effects. Healthy IAQ is not only a consideration in existing multifamily dwelling units and many commercial buildings, but new construction as well. To better understand the IAQ of a building such as an apartment or condo, let’s think about the lifecycle of the building. Construction processes are inherently messy and leave behind dust and debris including known carcinogens. That “new carpet smell” that reminds the tenant that they’re the first person to occupy their apartment is also unhealthy. Off gassing from carpet and other manufactured materials refers to the release of airborne particles or chemicals and is just one source of VOCs. Paint is another obvious source of VOCs. However, others such as furniture and cabinetry also retain VOCs from chemicals introduced during the manufacturing process.


Once an apartment or office is occupied, several other sources of VOCs are introduced into the space. For example, chemical air fresheners and personal care items designed for their pleasant smell, may also contribute to poor IAQ. Some sources of VOCs, like paint fumes, may be more obvious than others. For example, scented (chemical) air fresheners and household cleaners may contain phthalates and other compounds that cause negative health effects.

Humidity is another important component of IAQ. Inadequate moisture control primarily in the bathrooms or locker rooms may lead to mold and mildew issues. These fungi not only not only present an aesthetic problem by covering everything from walls and clothing, mildew and mold also cause health concerns. The ideal relative humidity in a building is between 50-60%. In certain conditions, mold can form in as little as ten days if the relative humidity is above 80%. Relative humidity levels even slightly above the 50-60% range can cause damages to finishes, walls, ceilings and equipment over time. Poor IAQ affects everyone, but is particularly bad for children, elderly and those with preexisting medical conditions. Symptoms of exposure to mold or VOCs may include common allergic responses (i.e. stuffy nose, wheezing and itchy or red eyes) or more significant issues for long term exposure and/or those with asthma or other health concerns. More extreme cases of VOC exposure can result in damage to organs, the central nervous system, and even certain forms of cancer.

Mechanical Ventilation Systems

The best solution to lessen exposure to unhealthy VOCs, mold and other pollutants, and still maintain an acceptable level of indoor air quality is a mechanical ventilation system. In addition to spot ventilation in the bathroom, a ceiling exhaust fan may also operate as a whole house ventilation (WHV) system. Fans used for WHV are often capable of operating at two speeds. Typically, the fan runs continuously on low speed and ramps up to high speed on demand. This demand varies, but it could be something as simple as turning on the lights and fan when the bathroom is occupied.

The addition of controls such as humidity sensors and motion sensors make control of the ceiling exhaust fan more automated. This ensures the fan operates as needed to maintain acceptable indoor air quality. In addition to controls, a quiet ceiling exhaust fan is also recommended. Fans having a sound rating of less than one sone on low speed are advised so that fan operation isn’t an annoyance to the occupant. Studies show that if a bathroom fan is excessively loud, the occupant will seldom use it.  

The dangers of poor IAQ from VOCs, mold and other pollutants affect the health of a building’s occupants. However, those dangers also have financial implications for the building owner. Poor IAQ can also result in lower occupancy rates in buildings.

What is the best ceiling exhaust fan for your application? Check out the following resources.

Indoor Air Quality
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Craig Kuski
Craig Kuski
Craig Kuski
Craig Kuski is an Application Engineering Specialist in the ceiling exhaust fan unit. He has been with Greenheck for nearly 9 years, holding positions in several fan groups.
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