Building-related illness and building-related symptoms

INTRODUCTION — 

In industrialized countries, most people spend more than 90 percent of their time indoors, and more than half of employed adults work in offices or similar nonindustrial environments [1,2]. Symptoms and illnesses related or attributed to indoor environments are common. A variety of factors associated with the environment and with the patient impact these symptoms, which may reflect new disorders, exacerbation of preexisting conditions (eg, rhinitis, asthma), and/or disorders caused by specific workplace exposures (eg, occupational asthma, hypersensitivity pneumonitis). Building-related symptoms can have a substantial impact on health. It is important for the clinician to recognize when symptoms are related to the patient's workplace, as these should be treated as occupational illnesses.

This topic will discuss building-related illnesses and symptoms, including epidemiology, potential exposures, host and building factors, and an approach to the patient with work-related illness. The discussion will focus on nonindustrial indoor work environments and schools, although many of the same exposures also exist in homes.

TERMINOLOGY — 

Several terms have been used to categorize syndromes of symptoms related to the indoor environment. Building-related symptoms or illnesses are considered work related if the indoor work exposures caused the illness or exacerbated a preexisting condition.

Building-related illnesses — Building-related illnesses are disorders that are associated with a particular building or indoor environment and meet diagnostic criteria for a specific illness. In some cases, a discrete causative agent can be implicated, but more often this is not possible. (See 'Building-related symptoms' below.)

Building-related illnesses can vary in severity and acuity. Examples are listed in the table and include the following (table 1):

●Rhinitis and asthma (ie, irritant or allergen induced, de novo, or exacerbated) (see "Allergic rhinitis: Clinical manifestations, epidemiology, and diagnosis" and "Chronic nonallergic rhinitis" and "Asthma in adolescents and adults: Evaluation and diagnosis")

●Dermatitis (common causes include low relative humidity or "chapped skin," or exposure to irritants such as fiberglass insulation) (see "Common allergens in allergic contact dermatitis" and "Irritant contact dermatitis in adults")

●Hypersensitivity pneumonitis (see "Hypersensitivity pneumonitis (extrinsic allergic alveolitis): Clinical manifestations and diagnosis" and "Hypersensitivity pneumonitis (extrinsic allergic alveolitis): Epidemiology, causes, and pathogenesis")

●Legionnaires' disease caused by dissemination of Legionella pneumophila via contaminated air-conditioning systems

Building-related symptoms — Building-related symptoms are symptoms that occur when the individual is in a specific building but are not easily categorized as a single definable illness. In the past, these presentations were often grouped under the term "sick building syndrome," but this term had limited descriptive utility and implied that the building was ill rather than the patient. In addition, it became clear over time that building-related symptoms are, in fact, common and occur in many ordinary workplaces. For these reasons, the term "sick building syndrome" is rarely used in the current literature, and "building-related symptoms" is preferred and reflects a more patient-centered approach.

Building-related symptoms typically begin after entering the work building and may improve or resolve upon leaving the building. In the case of allergic or asthmatic symptoms, responses can be delayed by several hours. Over time, symptoms may become more frequent or persistent and may be triggered more nonspecifically by numerous exposures.

Commonly reported building-related symptoms include:

●Mucous membrane irritation – Itchy, watery, or dry eyes; stuffy or runny nose; sinus congestion; dry or scratchy throat

●Chest symptoms – Cough, chest congestion, dyspnea, wheezing, increased use of asthma medications

●Skin symptoms – Rashes, dry or itchy skin

●General or neurologic symptoms – Fatigue, difficulty concentrating, headaches, dizziness, myalgia

●Sensory symptoms – Abnormalities in taste or smell, perception of strong smells

Indoor air quality — Indoor air quality refers broadly to the quality of air within buildings constructed for nonindustrial business or for residential purposes. Indoor air quality is affected both by indoor emissions and pollutants as well as by outdoor air quality since outdoor air is the source of air circulated within a building.

EPIDEMIOLOGY

Prevalence — Building-related illnesses and symptoms are common. Several cross-sectional studies and reports on "problem buildings" have investigated the prevalence of symptoms attributed to the nonindustrial work environment, and up to 60 percent of workers have reported at least one symptom related to the environment at work [3,4]. However, the general prevalence of building-related illnesses and symptoms is largely unknown, given the lack of a definitive test or set of criteria for establishing the diagnosis.

Reported outbreaks of specific building-related illness are infrequent and are most often infectious. (See 'Infectious agents' below.)

Clusters of hypersensitivity pneumonitis cases have been described, but these have most commonly occurred outside of office environments (eg, "hot tub lung," a hypersensitivity pneumonitis linked to nontuberculous mycobacteria). (See "Overview of nontuberculous mycobacterial infections", section on 'Clinical manifestations'.)

INDOOR EXPOSURES — 

In industrialized countries, people spend approximately 22 hours per day indoors [1,2,5]. Nonindustrial indoor environments can be a source of substantial exposures that impact health and productivity. Indoor air pollution may come from toxic or irritant chemicals (eg, carbon monoxide, tobacco smoke, or cleaning products); allergens; infectious agents; or indoor combustion products, such as from cooking, natural gas stoves, and candles (table 2) [6]. Symptoms are rarely caused by a single exposure; more often, the patient is reacting to a combination of factors.

At present, there is not a single set of standards for indoor air quality in the United States, although there are standards for specific "criteria pollutants," as discussed below. (See 'Criteria pollutants' below.)

Exposures in specific environments — More than one-half of employed adults work in offices or similar nonindustrial environments. Children and adolescents spend significant portions of their day in school buildings, which are typically older and less well maintained than office buildings [7].

Schools — Poor ventilation has been identified as a common problem in many schools [7]. Schools are also a major site of exposure to cleaning products, molds, dust, dander from cats and dogs, and diesel exhaust from school buses [8]. Infectious outbreaks, particularly with viral illnesses, are common in school environments. Outbreaks with less common but communicable pathogens such as meningococcus, Legionella, or tuberculosis also occur. (See 'Infectious agents' below.)

Restaurant and entertainment venues — Bars, restaurants, casinos, movie theaters, and other hospitality and entertainment venues are associated with many exposures, including environmental tobacco smoke in some settings, although there has been legislative curtailment of indoor smoking in many countries. Cooking fumes can be respiratory irritants.

Health care facilities — Health care workers are exposed to numerous allergens and irritants. Allergy to natural rubber latex received significant attention as glove use became more widely adopted in the 1990s to avoid bloodborne pathogen exposure. Latex glove use has since declined, but numerous other allergens are present in the health care environment, such as pharmaceuticals (eg, psyllium, antibiotics, chemotherapeutics, aerosolized medications), disinfectants and sterilants (eg, glutaraldehyde, formaldehyde), and cleaning products [9]. Many of the disinfectants, sterilants, and cleaning products are also strong irritants. (See 'Cleaning and personal care products' below.)

Specific exposures — Important indoor pollutants include secondhand smoke, molds and other allergens, volatile organic compounds, particulate matter and other specific gases, cleaning and personal care products, and emissions from cooking and heating. Infectious agents present another type of exposure.

Secondhand smoke — Many terms are used for the involuntary inhalation of tobacco smoke by nonsmokers, including secondhand smoke (SHS) exposure, environmental tobacco smoke exposure, and passive smoking. SHS exposure is associated with increased risk for respiratory symptoms, cardiovascular events, and lung cancer. (See "Secondhand smoke exposure: Effects in adults".)

SHS has been named a carcinogen by the US Environmental Protection Agency (EPA) [10]. In the United States, legislation banning smoking varies from one state or locality to another, and bans are being increasingly implemented across the country restricting smoking in restaurants and/or bars and public or government buildings. The American Lung Association (ALA) tracks state tobacco control laws in the United States in a database that can be accessed at the ALA tobacco legislation website. At least 25 countries in Europe have also enacted legislation banning smoking in some public areas [11]. Although smoking is becoming less common in many workplaces, SHS remains an important source of symptoms and morbidity, and patients should be asked about SHS both at home and at work. (See "Control of secondhand smoke exposure".)

Overall, smoking bans have resulted in improvements in respiratory and sensory symptoms, lung function, and cardiovascular events in adults, as well as improvements in perinatal and child health [12,13]. Studies examining the effects of workplace smoking prohibition on the health of hospitality workers have shown a decrease in respiratory symptoms and sensory irritant symptoms and improvements in lung function [14].

Electronic nicotine delivery systems — Electronic nicotine delivery systems (ENDS), including e-cigarettes, are widely used, both as smoking cessation devices and for recreational use. E-cigarettes are battery-powered devices that heat and aerosolize liquid to be inhaled. Most such liquids contain nicotine. Use among adolescents in particular has increased at a rapid pace [15]. Concern has arisen about health effects of nonusers exposed to ENDS aerosols that can contain toxicants including nicotine as well as fine and ultrafine particles, similar to SHS exposure [16-18]. Use of ENDS may occur in indoor areas where other forms of smoking are prohibited, subject to local regulations [19]. Organizations such as the American College of Physicians, the Forum of International Respiratory Societies, and the World Health Organization (WHO) have called for restrictions on use of ENDS in indoor and public spaces, as well as for research to determine health effects of ENDS to users and nonusers [17,19,20]. As of 2016 in the United States, the US Food and Drug Administration (FDA) has extended its regulatory authority to include all tobacco products, including nicotine-containing ENDS or ENDS marketed for therapeutic purposes such as for smoking cessation [21].

Research on chemical contents and health effects of ENDS is evolving rapidly. These topics are covered elsewhere in more detail. (See "Vaping and e-cigarettes" and "Control of secondhand smoke exposure", section on 'Electronic cigarette secondhand vapor exposure'.)

Mold — Mold and dampness are common exposures in buildings and are frequently associated with upper respiratory and asthma symptoms [22]. The health effects of indoor mold are mentioned briefly here, and the assessment of indoor mold is covered elsewhere in more detail. (See "Assessment of mold in the indoor environment".)

Mold can become a problem in buildings with water damage and moisture problems. The most common illnesses linked to dampness and mold exposure are:

●Rhinitis and asthma – Dampness and indoor mold have consistently been associated with increased risk of asthma, asthma exacerbation, rhinitis, and respiratory infections in both atopics and nonatopics [23,24].

Other mold-related disorders include [25]:

●Allergic fungal sinusitis (see "Allergic fungal rhinosinusitis")

●Hypersensitivity pneumonitis – Occupational outbreaks of hypersensitivity pneumonitis are uncommon but do occur (see "Hypersensitivity pneumonitis (extrinsic allergic alveolitis): Epidemiology, causes, and pathogenesis", section on 'Ventilation and water-related contamination')

Sarcoidosis has also been described in association with water-damaged buildings and other occupational settings contaminated with mold or mycobacteria, leading to the hypothesis that microbial antigens could be a trigger for granulomatous inflammation [26,27].

In contrast to allergic and hypersensitivity reactions, serious fungal infections are rare after exposure to environmental mold in immunocompetent patients.

While there is good evidence for the association between fungal exposure (and damp environments) and upper respiratory and asthma symptoms, the mechanistic underpinnings remain incompletely defined. A variety of fungal components such as beta-glucans, chitin, and proteases likely have important roles [28]. Many patients are concerned about mycotoxins, metabolites produced by some fungal species (eg, particular species of Stachybotrys), as a source of building-related symptoms, including headaches, difficulty concentrating, and fatigue. However, mycotoxins are most often nonvolatile large molecules, and thus inhalational exposure requires significant aerosolization or disruption of fungal spores. Even when inhalational exposure occurs, the health effects of mycotoxins in the context of damp and poorly maintained buildings are not well understood [22].

Other allergens — Allergens, other than molds, can contribute to building-related symptoms. These include allergens from dust mites, cockroaches, rodents, and plant pollen (if drawn indoors from the immediate outdoor environment). Dander from domestic animals may also be carried from homes to work and school environments on clothing. Carpeting in workplaces can harbor allergen particles for long periods of time. The adverse effects of allergens can be augmented by coexposures such as ozone, nitrogen dioxide, and sulfur dioxide [29]. (See 'Criteria pollutants' below and "Allergen sampling in the environment".)

Infectious agents — Viral, fungal, and occasionally bacterial pathogens in buildings have been linked to outbreaks.

●Cold and flu viruses are the most commonly encountered infectious agents in nonindustrial indoor environments (eg, influenza spreads readily among health care workers). More recently, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission in indoor environments has played a major role in disease transmission. (See "COVID-19: General approach to infection prevention in the health care setting".)

●Tuberculosis outbreaks have been reported in workplaces, most commonly in health care facilities but also in schools and office buildings. (See "Tuberculosis transmission and control in health care settings".)

●Nontuberculous mycobacteria can contaminate water sources such as humidification systems.

●Legionellosis (Legionnaires' disease) is an important workplace concern, with many instances having been described since the first recorded outbreak in 1976 [30,31]. In that outbreak, multiple conference attendees were infected with the bacterium L. pneumophila that had contaminated an air-conditioning system in the conference hotel. Surveillance data from the Centers for Disease Control and Prevention show that reported cases of Legionnaires' disease have been increasing since the early 2000s [32]. (See "Microbiology, epidemiology, and pathogenesis of Legionella infection".)

Volatile organic compounds — Volatile organic compounds (VOCs) are carbon-containing compounds with a high vapor pressure at room temperature. VOCs are emitted from a variety of building and consumer products and are largely responsible for the "new carpet" or "new car" smell. VOCs can emanate from many indoor materials such as paints, floor finishes, furniture, carpeting, polyurethane spray foam insulation, and other building materials.

VOCs have been implicated in building-related symptoms such as upper airway and mucous membrane irritation, headaches, difficulty concentrating, irritability, nausea, and drowsiness [33-35]. VOC exposure in concentrations typically found in new office buildings was associated with an increase in nasal neutrophils 4 and 18 hours after laboratory exposure in a small study (14 subjects).

VOCs include volatile aromatic hydrocarbons, semivolatile organic compounds, and volatile aldehydes [33]. Common examples include formaldehyde, toluene, xylene, and benzene. Formaldehyde in indoor environments is primarily emitted by wood-based products assembled with formaldehyde-containing resins, such as plywood or particle board. Some paints and varnishes can also emit formaldehyde fumes. Formaldehyde is an airway and mucous membrane irritant, and it can cause respiratory symptoms, particularly in patients with underlying lung disease such as asthma. It is also a carcinogen associated with nasopharyngeal and sinonasal cancer in people chronically exposed [35].

Criteria pollutants — "Criteria pollutants" are six common outdoor air pollutants that the EPA is required to regulate based on the Clean Air Act:

●Particle pollution (or particulate matter)

●Ozone

●Carbon monoxide

●Nitrogen oxides

●Sulfur oxides

●Lead

Outdoor air pollutants are an important contributor to indoor air pollution [36,37]. Although data are most available for the six criteria pollutants, other outdoor pollutants may also become part of the indoor environment and cause symptoms. These pollutants are also important factors in indoor air quality globally. Although primary sources of pollutants may differ from country to country, several pollutants are common across countries. The WHO has published guidelines for indoor air quality that include several of these pollutants [38]. Additionally, the WHO global air quality guidelines, which cover the criteria air pollutants, are applicable to both outdoor and indoor environments [39].

●Indoor particulate matter (PM) comes from sources such as house dust, resuspension of disrupted particles, environmental tobacco smoke, or combustion products of cooking or heating. Indoor burning of biomass fuels for heat or cooking is a common source of PM in many resource-limited countries. Indoor PM, by itself, can cause symptoms, or particles may carry other pollutants into the respiratory tract [1]. Indoor PM has been associated with respiratory health effects such as wheezing and cough.

PM ranges in size and is classified as:

•Coarse (2.5 to 10 micrometers)

•Fine (0.1 to 2.5 micrometers)

•Ultrafine (<0.1 micrometers)

Coarse matter will deposit in the upper airway, whereas fine and ultrafine particulate can deposit deep in the tracheobronchial tree or alveoli. To put these dimensions in perspective, the average diameter of a human hair ranges from 30 to 100 micrometers.

●Ozone has been associated with morbidity and mortality in studies analyzing outdoor ozone concentrations [40]. Ozone is also present in indoor air, primarily from circulating outdoor air but also from appliances such as ionizing air purifiers or ozone-generating air cleaners [1]. Acute exposure to ozone can cause airway inflammation, decline in pulmonary function, and decline in exercise tolerance in both healthy people and those with preexisting reactive airways disease. Ambient ozone can enhance response to inhaled allergens in susceptible people [1].

●Carbon monoxide is released into indoor air by furnaces or stoves, particularly if they are not functioning properly. Indoor open flame cooking is a common source of CO in many resource-limited countries. In industrial settings, the most common source of CO is vehicle exhaust from garages or indoor use of equipment such as forklifts. In any setting, outdoor vehicle exhaust can enter the ventilation system, particularly if idling vehicles are parked near intake vents. Environmental tobacco smoke is also a source of CO. Low-level chronic CO exposure can contribute to exacerbations of cardiopulmonary disease and symptoms such as headaches, nausea, dizziness, fatigue, dyspnea, and neuropsychological impairment [1]. (See "Carbon monoxide poisoning".)

●Nitrogen dioxide and sulfur dioxide are products of combustion of fossil fuels and natural gas, and both are airway irritants. In the indoor environment, nitrogen dioxide may be emitted from furnaces or stoves. Indoor levels may exceed outdoor levels if appliances are not vented properly [6]. Nitrogen oxides can cause increased bronchial responsiveness and enhanced response to inhaled allergens in both healthy and asthmatic patients [41]. Sulfur dioxide can cause symptoms of wheezing and chest tightness as well as frank bronchoconstriction in individuals with asthma [1].

●Lead remains an important indoor exposure globally. Historically, leaded gasoline, lead-based solder, and lead paint have been major sources of lead in the environment. These have been greatly reduced or eliminated in resource-abundant countries, although dust from preexisting lead paint continues to be a source of respirable lead, particularly during renovations. Another example of lead in the indoor environment is lead dust from indoor shooting ranges used either for recreational shooting or training. Elevated blood lead levels have been well documented in people frequenting such shooting ranges, both in the United States and internationally [42]. Lead dust from shooting ranges can also be tracked into homes and other indoor spaces.

Adequate ventilation and cleaning of lead-contaminated surfaces are two important controls to limit indoor lead exposure. Elevated blood lead levels can have adverse effects at numerous sites throughout the body (see "Lead exposure, toxicity, and poisoning in adults: Clinical manifestations and diagnosis"). Lead exposure is particularly concerning in children. (See "Childhood lead exposures: Exposure and prevention".)

Cleaning and personal care products — Industrial and domestic cleaning products have been repeatedly implicated in occupational asthma and dermatitis [9]. Cleaning products containing a variety of noxious substances are often used in combination. Such ingredients include solvents (eg, ammonia, ethanol, isopropanol), alkalis (eg, bleach), acids (eg, phosphoric acid, acetic acid, hydrochloric acid), and antimicrobial agents (eg, glutaraldehyde, quaternary ammonium chlorides) [9]. Many of these compounds are strong respiratory and dermal irritants, and others, such as glutaraldehyde, can also cause allergic sensitization. The mixing of cleaning products can result in toxic byproducts, such as acute asthmatic responses or toxic pneumonitis. Notably, mixing bleach and ammonia results in the release of toxic chloramines, which can be lethal at high levels. (See "Irritant-induced asthma" and "Chronic nonallergic rhinitis".)

Odor perception is strongly associated with building-related symptoms [43]. Symptoms induced by the odors of chemicals or perfumed personal care products are common complaints. Cleaning products are also commonly implicated. Odors may also come from environmental sources, and the Agency for Toxic Substances and Disease Registry and the Centers for Disease Control and Prevention have developed a website with information and resources about odors. Notably, odor perception thresholds are variable from person to person and, therefore, not all occupants will be equally impacted by a given odor.

Emissions from cooking and heating — Burning of biomass fuels (eg, wood, animal dung, coal, plants) produces pollutants such as carbon monoxide, nitrogen dioxide, formaldehyde, benzene, polyaromatic hydrocarbons, and particulate matter [44]. Much attention has been paid to the adverse health effects of burning these fuels in resource-limited countries. However, emissions from cooking and heating can also be an important source of pollutants in the industrialized world [20]. Grilling over charcoal or using wood-burning stoves at home or in restaurants are examples. Reported health effects from heating and cooking emissions include asthma and other respiratory symptoms, increased risk of respiratory tract infections including tuberculosis, sensitization to aeroallergens, and cancers such as lung, cervical, and upper aerodigestive tract [44-46]. The WHO has updated its guidelines on indoor air quality in relation to household fuel combustion [47].

BUILDING FACTORS

Role of engineering and ventilation — Ventilation is the process of exchanging indoor air with outdoor air to create a comfortable indoor environment for humans. Inadequate ventilation is one of the most common factors contributing to building-related symptoms and illness. The National Institute for Occupational Safety and Health (NIOSH) found that roughly one-half of its indoor air quality investigations revealed a problem with inadequate ventilation [48]. Complaints related to poor ventilation may reflect high concentrations of indoor pollutants. Inadequate air exchange, inadequate distribution of ventilated air, and ventilation of polluted outdoor air are primary issues. Improper maintenance of heating, ventilation, and air-conditioning systems contributes to an increased prevalence of symptoms among occupants and has also been linked to outbreaks of legionellosis [30,49,50]. The proportion of fresh (outdoor) air versus recirculated air is also an important factor in indoor air quality.

There is a well-documented association between increased ventilation rates and decreased symptoms, including headaches, respiratory symptoms, nose and throat symptoms, and skin complaints [51,52]. Mechanical ventilation systems also include filters for particulate matter (PM) that can limit fine smoke particles, allergens, viruses, and other particles. Filter efficiencies vary, and filters must be maintained (cleaned or replaced) regularly to be effective. The United States General Services Administration maintains a website with extensive information on enhancing health through ventilation and other building design factors that optimize indoor air quality.

Measurement of carbon dioxide — The adequacy of fresh air circulating in a building is often measured indirectly via carbon dioxide (CO₂) levels. CO₂ is a marker for inadequate ventilatory exchange rates. Humans are the primary source of CO₂, and concentrations will vary widely based on room and building occupancy [53]. Indoor air concentrations of CO₂ typically range between 500 and 1500 parts per million (ppm), while outdoor concentrations are generally 350 to 450 ppm [54]. A rough guideline is that CO₂ concentrations should not exceed 1000 ppm in indoor environments for comfortable air quality [2,55]. However, low measured levels of CO₂ do not necessarily rule out inadequate ventilation, because CO₂ levels are dependent on how many occupants are in the space when the levels are measured.

Ventilation rates used to achieve desirable air quality levels must take into account the size and usage of the space, the number of occupants, the duration of occupancy, and the volume of the room [54]. A rough guide is that ventilation rates at or below 10 L/second per occupant are associated with increased symptoms among building occupants [49]. However, some studies suggest that outdoor air supply rates as high as 25 L/second per person are necessary for health and comfort [49]. Specific recommendations can be found in the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) standards. There are similar standards internationally, written by the International Organization for Standardization (ISO) and the European Committee for Standardization (CEN) [56].

Temperature and humidity — Building temperature and humidity have been consistently linked to building-related symptoms. Temperature and humidity ranges suggested by various organizations are guidelines. Individual perceptions of comfort will vary within these ranges and may be influenced by additional factors such as age, gender, and smoking.

Temperatures over 22 to 23°C (71.6 to 73.4°F) are associated with increased symptoms, including mucosal irritation, headache, and fatigue [2]. The Occupational Safety and Health Administration (OSHA) recommends temperature control between 68 and 76°F [57]. ASHRAE, in the latest iteration of Standard 55, specifies thermal comfort based on the combination of six factors: metabolic rate, clothing insulation, air temperature, radiant temperature, air speed, and humidity [55].

Indoor humidity is highly linked to outdoor humidity in buildings with ventilation systems circulating largely outdoor air. Low indoor relative humidity (<20 to 30 percent) has been associated with irritant symptoms such as ocular dryness, upper respiratory symptoms, and skin symptoms [58]. High relative humidity (>60 to 65 percent) can also contribute to symptoms by harboring microbial growth or causing excessive water condensation. Biocides may be added to humidification systems to prevent microbial growth, but many of these biocides are irritants themselves. OSHA recommends humidity control between 20 to 60 percent [57], and ASHRAE recommends humidity levels be limited to 65 percent or less [55] for occupants' comfort. The US Environmental Protection Agency (EPA) further recommends maintaining a relative humidity of <60 percent to control mold growth and <50 percent to control dust mites, including during hours a building is unoccupied.

Building renovation and construction — Renovation work is common in many building environments. Renovation can generate construction dusts and disruption of building materials that may contain molds, allergens, or chemical products. The age of a building can suggest specific exposures of concern that may have been used in building materials, such as asbestos, lead, or polychlorinated biphenyls (PCBs). PCBs, for instance, were commonly used in schools and other buildings building in the 1950s, 1960s, and 1970s [59]. Asbestos and PCBs exposures are implicated in long-term health effects rather than acute symptoms. Their health effects in adults generally occur in a dose-dependent fashion, but their presence may be of concern to patients.

Green buildings — There has been a growing movement in the United States and other countries to adopt more environmentally friendly building design and construction standards, or "green" building practices (ie, building practices that have minimal impact on the ecosystem by minimizing energy and resource utilization). The Leadership in Energy and Environmental (LEED) certification program is one widely used example of rating buildings for green design. LEED heavily weights features such as energy efficiency and low-toxicity building materials. Less emphasis is placed on indoor air quality.

Although building materials and furnishings are selected for low toxicity, chemical emissions remain possible. For example, wood may be selected for low formaldehyde emissions but may result in wood with phenol emissions, which may have different health effects. Thus, while there are environmentally positive aspects for green buildings, our understanding of the impact on occupant health continues to evolve.

The growing literature on the health impacts of green buildings and healthy building design focuses primarily on symptoms, comfort, and productivity [60,61]. Some studies have shown perceived improvements in respiratory symptoms and stress after green renovations of low-income housing [62] or moving the workspace from a conventional to a green office space [63]. A 2015 review concluded that green buildings achieved better measured and perceived indoor environmental quality, although satisfaction with indoor acoustics was lower in green buildings in several of the studies reviewed [64]. However, not all studies have demonstrated improvement in perceived occupant comfort or satisfaction [65]. With respect to health outcomes, in a study of children living in green public housing in an urban setting, there was improvement in asthma morbidity compared with those living in conventional housing [66].

HOST FACTORS — 

As is true for most illnesses, factors inherent to the patient influence their susceptibility to indoor air pollution.

Atopy, allergy, and/or bronchial hyperreactivity — In general, patients with atopy, rhinitis, or asthma are more likely to report building-related symptoms [67]. Patients with atopy or asthma may be more likely to respond to irritants and allergens such as cleaning products and environmental tobacco smoke. Patients with atopy or allergy are also at higher risk of work-related rhinitis and contact dermatitis.

Psychosocial work factors — Stress has been implicated as a potential risk factor for building-related complaints. The demand-control-support paradigm of psychosocial work factors has been used in occupational health. High work demand, low job control, and low support have been related to increased prevalence of building-related complaints [67,68].

Gender — Symptoms related to the indoor environment are reported more commonly by women [2,67-69]. This may be because of gender variations in work environment or work tasks, sensitivity to environmental factors, or a difference in rate of reporting [2,67,68].

Other — A variety of other host factors have been studied, including age, educational level, and socioeconomic status. The evidence linking these factors to symptoms in the indoor environment has not been consistent. These host factors are interrelated, and the relationships are complex and vary across industries and geographic populations.

APPROACH TO THE PATIENT — 

Suspicion for building-related illnesses should be raised by symptoms affecting the upper and lower respiratory tracts (including mucous membranes), the skin, and the neurologic system (eg, headaches, tingling sensations). Suspicion should also be raised if such symptoms persist in a subacute or chronic nature without any other obvious cause. Allergic and irritant symptoms, including asthma, warrant more investigation for possible building-related triggers.

When evaluating a patient with a symptom or illness that is potentially related to a specific environment, the first step is to elicit the history of specific symptoms, examination findings, and any diagnostic testing and to determine if there is a unifying diagnosis, clinical syndrome, or disorder, such as asthma or rhinitis. Most patients with building-related symptoms commonly have an underlying condition(s) such as rhinitis, allergic conjunctivitis, and/or asthma, in the authors' experience (table 1).

After this, the relationship between the illness or symptoms and the patient's work or other indoor environments should be evaluated. The clinician should attempt to address the following questions:

●Can the disorder or symptoms reasonably be attributed to or aggravated by a specific indoor environment? Are the patient's symptoms temporally related to a specific indoor environment?

●Does the patient report possible causative factors in the indoor environment such as recent renovation, water damage, cleaning products, and/or poor ventilation? Are other people in the same building similarly affected?

Clinical history — It is helpful to have a "diagnostic checklist" of questions to assess any links to the indoor environment [70]:

●When did the symptoms start?

●Do the symptoms occur all the time or do they come and go?

●Are there certain times of day or days of the week when the symptoms are usually present? If yes, is the patient in any particular building or area during those times?

●Do symptoms improve or go away upon leaving that building or area? Do symptoms come back when upon return?

●What does the patient think is the cause of symptoms?

●Has the patient changed the amount of medication they are using in an attempt to counter the symptoms?

●Are there other occupants of the building that are also having symptoms?

Environmental and occupational history — A thorough occupational and environmental history is the most valuable clinical tool in assessing a patient with symptoms that may be related to a specific indoor environment. In addition, it can be helpful to ask the patient to keep a diary documenting their symptoms in conjunction with the location (eg, home or at work) and specific work tasks or activities they were performing at the time of the symptoms. The full occupational and environmental history is discussed in greater detail separately. (See "Overview of environmental health", section on 'History'.)

A basic environmental history should include an assessment of both the work and home environments, with questions addressing the temporal relationship of symptoms to both settings.

Specific questions include:

●What do you do for work? Describe your work environment.

●Have there been any recent renovations, refurnishing, or construction at home, school, or work? Has there been any recent water damage?

●Have you recently moved homes or workplaces?

●Are you exposed to environmental tobacco smoke at home, school, or work?

●Are you frequently exposed to cleaning products?

●Is there visible dust at home, school, or work?

●Do strong odors, such as perfumes, cause bothersome symptoms?

●Do you feel your work (or home) environment is "stuffy" or "stale"? Does your work (or home) environment feel too dry or too humid?

●Have you recently acquired any new pets?

If the patient suspects a problem with specific products or chemicals to which they are exposed, the employer is required to provide material safety data sheets (SDSs) that the employee can bring to a medical appointment for review by their clinician. If the exposure is from a commercially available household product, information is available online for many of the products sold in the United States and Canada (eg, Consumer Product Information Database).

Physical examination — A detailed examination should pay particular attention to the eyes, ears, nose, throat, lungs, and skin. A thorough neurologic examination may also be helpful in patients with more general or sensory symptoms.

WORKPLACE EVALUATION — 

If, after the occupational and environmental history, more information about the indoor environment is needed, a workplace evaluation can be performed. A basic workplace evaluation can first be performed by the patient, and patients can be instructed to look for obvious dust or water damage, noting any obvious odors, and getting a sense of whether the space seems stuffy, too hot or cold, or too dry or humid.

A more detailed investigation of the work environment will likely require cooperation from the employer. The clinician should discuss this with the patient first and get the patient's permission to contact the employer. Many patients have little control over their work environments, and some may be concerned about job security. However, clinicians can often help facilitate appropriate changes.

The initial step of a workplace evaluation is a qualitative walkthrough to view the workplace and gather information about the building (eg, usage history, renovations, qualitative evaluation of ventilation, history of health complaints, interviews of occupants). If necessary, a more detailed evaluation may involve sampling carbon dioxide levels; evaluating heating, ventilation, and air-conditioning (HVAC) systems; or sampling for other pollutants such as volatile organic compounds (VOCs). The more detailed workplace evaluation will typically involve a team including a clinician, an industrial hygienist, and possibly a building and ventilation engineer.

Extensive air or surface sampling is rarely indicated and can be expensive and of little benefit. Mold and allergen sampling of the environment, in particular, is costly and often undertaken prematurely or inappropriately. Molds and allergens are ubiquitous in the environment, and there are no standards for "safe" levels. Allergen and mold sampling are discussed in greater detail separately. (See "Allergen sampling in the environment" and "Assessment of mold in the indoor environment".)

DETERMINATION OF BUILDING RELATEDNESS/WORK RELATEDNESS — 

Once the diagnosis is clarified and the information about the indoor environment has been ascertained, the clinician can then establish the connection between the building exposure(s) and the patient's symptoms and/or diagnosis. This is done by correlating the known health effects of the exposure(s) in question (the most common of which are covered above) with the patient's symptoms and/or diagnosis: Can the symptoms and/or diagnosis reasonably be attributed to or aggravated by the specific indoor environment?

The threshold of establishing medical causation for workers' compensation is that it is "more probable than not" that the illness or injury is caused or exacerbated by work. Patients diagnosed with probable work-related illnesses should be informed of relevant workers' compensation programs, similar to work-related injuries. It is also important that the clinician share with the patient concerns about work relatedness in a timely manner as there is usually a statute of limitations for work-related illness or injury that varies under different states' workers' compensation systems. (See "Disability assessment and determination in the United States", section on 'Workers' compensation'.)

DOCUMENTATION — 

It is important that the clinician carefully document the history, symptoms, examination findings, diagnostic testing, and particularly any association with the work environment. The last should include any temporal or spatial relationships to work, association of symptoms with a specific work area or job task, improvement in symptoms away from work, increased use of medications (such as for allergy or asthma symptoms), more frequent medical visits, or more sick days associated with work-related symptoms. A thorough medical and occupational evaluation with detailed documentation is important for diagnosis and management as well as for issues of worker's compensation.

MANAGEMENT — 

The medical management of defined conditions (such as asthma or rhinitis) is similar, whether the disorder is building related or not. It is important to reduce (or eliminate) exposure to causative factors or agents in the indoor environment of concern.

The majority of building-related illnesses and symptoms are related to more than one exposure combined with inadequate ventilation, as mentioned previously. Interventions that improve the indoor air quality can be very successful. These include reducing exposures (most commonly dust, cleaning products, perfumes, dampness) and optimizing ventilation systems, including fresh air intake, temperature, and humidity. Decreasing tobacco smoke exposure can also improve symptoms.

Less frequently, a specific exposure is suspected to be the source of the illness. Examples include hypersensitivity pneumonitis and many cases of work-related asthma caused by specific sensitizing agents. In such cases, identifying the causative exposure is much more critical and also most likely to be successful if attempted prior to the clinician recommending complete removal from the suspected workplace.

There are many interventions to improve indoor air quality that clinicians can recommend, and patients can initiate themselves or bring to the attention of their supervisor or employer. A guide for clinicians and patients is the US Environmental Protection Agency (EPA)’s Office Building Occupant's Guide to Indoor Air Quality [71]. State and local health departments are also sources of helpful information. (See 'Resources' below.)

Communicating with employers — With the patient's permission, the clinician may be able to facilitate constructive changes by contacting the employer by phone or in writing for additional information about the work environment or to make recommendations. Such communications should not contain medical information about the patient, and language should be neutral and nonaccusatory. Recommendations, such as evaluating the ventilation system (including fresh air intake, supply, and return in different rooms), fixing water leaks, use of "green" cleaning products, or relocation until renovation work is completed can be helpful. If other workers are also symptomatic, it can be helpful for those workers also to be evaluated. Again, having the patient's permission is essential before contacting an employer.

Reporting — If a workplace is involved, clinicians should report building-related illnesses as they would report any other occupational disease or injury to comply with their state's occupational health surveillance initiatives. Clinicians can also report serious concerns about a dangerous workplace directly to the Occupational Safety and Health Administration (OSHA).

RESOURCES — 

Building-related symptoms and indoor air quality complaints are among the most common calls received by state and local health departments. Some departments have dedicated indoor air "officers." Many health departments have developed helpful documents and tools available on their websites, including fact sheets with patient-friendly information (eg, Connecticut Department of Public Health fact sheet on testing indoor air). Involvement of an occupational and environmental medicine practitioner may be helpful in certain situations. In the United States, local consultants in environmental medicine can be found through the or the 's Doctor Finder tool.

There are national resources as well. In the United States, the Environmental Protection Agency (EPA), the National Institute for Occupational Safety and Health (NIOSH), and the Occupational Safety and Health Administration (OSHA) all have website resources. These include resources for schools [72]. If multiple workers are experiencing similar symptoms, there are several available avenues for assistance. While the state or local health department is still a good first resource, additional options include:

●Employees can request help directly from NIOSH through the Health Hazard Evaluation Program. NIOSH is not a regulatory agency, and they will respond in writing with helpful information or a referral to another agency, or they may choose to do a site visit to investigate further.

●Owners of small- or medium-sized businesses can also request assistance from OSHA through its On-Site Consultation Program. The program is designed to assist concerned employers in recognizing and remediating health hazards in the workplace. It is free and separate from any enforcement.

SUMMARY AND RECOMMENDATIONS

●Terminology and epidemiology – Building-related illnesses are disorders that are associated with a particular building or indoor environment and meet criteria for a specific illness. Building-related symptoms are symptoms that occur when the individual is in a specific indoor environment but are not easily categorized as a single definable illness. Building-related illnesses and symptoms are common in nonindustrial environments, such as offices and schools. Precise estimates of prevalence are lacking. (See 'Terminology' above and 'Epidemiology' above.)

●Indoor exposures – Indoor exposures in nonindustrial environments include toxic or irritant chemicals such as cleaning products, volatile organic compounds (VOCs), dust, allergens, infectious agents, fragrances, tobacco smoke, and extremes of temperature and humidity (table 2). At present, there are no formal standards for indoor air quality in the United States. (See 'Indoor exposures' above.)

●Causative factors – The majority of building-related illnesses and symptoms result from a combination of exposures combined with inadequate ventilation. Less commonly, a building-related illness can be linked to an identifiable causative agent (eg, hypersensitivity pneumonitis, allergic asthma related to a sensitizing agent). Host factors, such as bronchial hyperreactivity and psychosocial work issues, play a role in some cases. (See 'Building factors' above and 'Host factors' above.)

●Role of the clinician

•Clinicians can provide significant help to patients by taking a thorough history of the home and workplace and identifying associated symptoms. Occupational medicine and industrial hygiene teams can assist in more complex workplace evaluations and recommendations. (See 'Approach to the patient' above.)

•The medical management of defined conditions (such as asthma or rhinitis) is similar, whether the disorder is building related or not. Reducing exposures and optimizing ventilation can decrease a wide range of symptoms, including headaches, respiratory symptoms, nose and throat symptoms, and skin complaints. (See 'Management' above.)

•Clinicians should report building-related illnesses in compliance with their state's occupational health surveillance initiatives. State and national resources are available to assist clinicians and their patients in the evaluation and management of suspected building-related illness. (See 'Reporting' above and 'Resources' above.)