Merck Manual

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Building-Related Illnesses


Abigail R. Lara

, MD, University of Colorado

Reviewed/Revised May 2020 | Modified Sep 2022
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Building-related illnesses are a heterogeneous group of disorders whose etiology is linked to the environment of modern airtight buildings. Such buildings are characterized by sealed windows and dependence on heating, ventilation, and air conditioning systems for circulation of air. Most cases occur in nonindustrial office buildings, but cases can occur in apartment buildings, single-family homes, schools, museums, and libraries.

Building-related illnesses can be specific or nonspecific. Diagnosis is based on history of exposure and clinical findings. Treatment is generally supportive.

Specific building-related illnesses

Specific building-related illnesses are those for which a link between building-related exposure and illness is proved. Examples include

Inhalational fever is a febrile reaction caused by exposure to organic aerosols or dusts. Symptoms begin 4 to 12 hours after exposure. Symptoms include fever, headaches, and general malaise. Names used to describe this type of building-related illness include humidifier fever, grain fever, swine confinement fever, and mycotoxicosis, depending on the causative agent. Metal fumes and polymer fumes can also cause febrile illness. The term organic dust toxic syndrome has been used to encompass the subacute febrile and respiratory reaction to organic dust that is typically highly contaminated with bacterial endotoxin. Toxic pneumonitis is a commonly used but less specific term.

Humidifier fever occurs in nonindustrial buildings as a consequence of humidifiers or other types of ventilation units serving as a reservoir for the growth of bacteria or fungi and as a method of aerosolizing these contaminants. The disorder usually manifests as low-grade fever, malaise, headaches, cough, and dyspnea. Improvement after removal from exposure (eg, weekend away from the office building) is often one of the first indications of etiology. Humidifier fever has an acute onset (eg, 4 to 12 hours after exposure) and is self-limiting (usually 2 to 3 days). Physical signs may be absent or subtle. Clusters of cases are common.

Unlike immunologically mediated conditions (eg, hypersensitivity pneumonitis Hypersensitivity Pneumonitis Hypersensitivity pneumonitis is a syndrome of cough, dyspnea, and fatigue caused by sensitization and subsequent hypersensitivity to environmental (frequently occupational or domestic) antigens... read more Hypersensitivity Pneumonitis , building-related asthma), inhalational fevers do not require a period of sensitization. The disorder can occur after initial exposure. Acute episodes do not generally require treatment apart from antipyretics and removal from the contaminated environment. If symptoms persist, evaluation may be required to rule out infection, hypersensitivity pneumonitis, or other conditions. Biologic sampling to detect airborne microbials in the work environment can be costly and time consuming but is sometimes necessary to document the source of contaminated air. Inhalational fevers of all types are usually prevented by good maintenance of ventilation systems.

Nonspecific building-related illnesses

Nonspecific building-related illnesses are those for which a link between building-related exposure and illness is more difficult to prove.

The term sick building syndrome has been used to refer to illnesses that occur in clusters within a building, but this term is falling out of favor and is being replaced by building-related illness. Building-related illnesses cause often nonspecific symptoms, including

  • Itchy, irritated, dry or watery eyes

  • Rhinorrhea or nasal congestion

  • Throat soreness or tightness

  • Dry itchy skin or unexplained rashes

  • Headache, lethargy, or difficulty concentrating

Some building-related factors appear to account for symptoms in some instances. These factors include higher building temperature, higher humidity, and poor ventilation, typically with a failure to incorporate sufficient fresh air from outdoors. Patient factors, including female sex, history of atopy, increased attention to body sensations, worry about the meaning of symptoms, anxiety, depression, and occasionally mass hysteria, also seem to underlie experience of symptoms.

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