INTRODUCTION — In industrialized countries, people spend more than 90 percent of their life indoors, and more than half of employed adults work in offices or similar nonindustrial environments [1-4]. 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)
●Dermatitis (common causes include low relative humidity or "chapped skin," or exposure to fiberglass insulation)
●Hypersensitivity pneumonitis
●Legionnaires' disease caused by dissemination of Legionella pneumophila via contaminated air-conditioning systems
These will be discussed in more detail below. (See 'Approach to the patient' below.)
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, very 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 [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 uncommon 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 [1-3]. 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, or infectious agents (table 2). 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 [4]. Children and adolescents spend significant portions of their day in school buildings, which are typically older and less well maintained than office buildings [5].
Schools — Poor ventilation has been identified as a common problem in many schools [5]. Schools are also a major site of exposure to cleaning products, molds, dust, dander from cats and dogs, and diesel exhaust from school buses [6-8]. 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. Food handlers are susceptible to allergic responses from antigens such as seafood, fruits, and wheat, either from skin contact or inhalational exposures [9]. 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 [10]. 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 [10]. 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) [11]. In the United States, legislation banning smoking varies broadly 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 [12]. 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 self-reported respiratory and sensory symptoms, lung function, and cardiovascular events as well as improvements in measurements of indoor air quality [13-16]. 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 as early as one to two months after smoking bans were enacted [17-21].
Electronic nicotine delivery systems — Electronic nicotine delivery systems (ENDS), including e-cigarettes, have surged in popularity, 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 [22]. 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 [23,24]. Use of ENDS may occur in indoor areas where other forms of smoking are prohibited, subject to local regulations [25]. 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 [24-26]. 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 [27].
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 [28]. 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 water-damaged buildings. 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 [29].
Other mold-related disorders include [30]:
●Allergic bronchopulmonary aspergillosis (see "Clinical manifestations and diagnosis of allergic bronchopulmonary aspergillosis")
●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 [31,32].
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 upper respiratory and asthma symptoms, the particular mechanistic underpinnings remain a subject of active investigation. A variety of fungal components such as beta-glucans, chitin, and proteases likely have important roles [33]. 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 [34]. 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 [28].
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 [35]. (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).
●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 uncommon workplace infection, but many instances have been described since the first recorded outbreak in 1976 [36]. In that outbreak, multiple conference attendees were infected with the bacterium L. pneumophila that had contaminated an air-conditioning system in the conference hotel. (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 [37-41]. 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) [38].
VOCs include volatile aromatic hydrocarbons, semivolatile organic compounds, and volatile aldehydes [37]. 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 [42]. Indoor formaldehyde concentrations have been negatively correlated with ventilator air exchange rates [42].
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 [43]. 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 [44].
●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 developing 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 symptoms 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 [45]. 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 developing 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 both are airway irritants. In the indoor environment, nitrogen dioxide may be emitted from furnaces or stoves. Indoor levels may exceed outdoor levels if heating appliances are not vented properly [42]. Nitrogen dioxide levels have also been positively correlated to ventilator air exchange rates in a building, implying that indoor concentrations are highly influenced by outdoor concentrations [42]. Although data conflict on the long-term effects of low-level exposure, increased bronchial responsiveness and enhanced response to inhaled allergens have been seen in both healthy and asthmatic patients [42,46]. 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 developed countries, although lead paint in particular is still available in many countries. 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 indoor shooting ranges used either for recreational shooting or for training of police or other armed personnel. Elevated blood lead levels have been well documented in people frequenting such shooting ranges, both in the United States and internationally [47-51]. Lead from bullets becomes respirable during weapon firing, and lead is very efficiently absorbed through the lungs.
Adequate ventilation and cleaning of lead-contaminated dust are two important controls to limit indoor lead exposure. Elevated blood lead levels are commonly asymptomatic, but more severely affected patients may present with anemia or abdominal pain (see "Lead exposure, toxicity, and poisoning in adults"). Elevated levels are also concerning in children whose intellectual development can be adversely affected. (See "Childhood lead poisoning: Exposure and prevention".)
Cleaning and personal care products — Industrial and domestic cleaning products have been repeatedly implicated in occupational asthma and dermatitis [10,52-54]. 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) [10,53]. 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 "Reactive airways dysfunction syndrome and irritant-induced asthma" and "Chronic nonallergic rhinitis".)
Odor perception is strongly associated with building-related symptoms, even in the absence of measurable or toxic levels of any specific compound [55]. Symptoms induced by the strong odors of chemicals or perfumed personal care products are common complaints among workers. Symptoms are often "sensory irritations," meaning that an odor may trigger eye and airway irritation via the trigeminal nerve [56]. This is not an allergic reaction, although patients with asthma, allergic rhinitis, and nonallergic rhinitis have been observed to have increased odor sensitivity [56,57]. Other compounds, such as VOCs, can induce similar reactions, but cleaning products and perfumed care products are most 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 (CDC) have developed a website with information and resources about odors. (See "Allergic rhinitis: Clinical manifestations, epidemiology, and diagnosis", section on 'Increasing sensitivity over time'.)
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 [58]. Much attention has been paid to the adverse health effects of burning these fuels in developing countries. However, emissions from cooking and heating can also be an important source of pollutants in the industrialized world [26]. 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 [58-60]. The WHO has updated its guidelines on indoor air quality in relation to household fuel combustion [61].
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. Ventilation-related problems account for as much as 60 percent of indoor air quality problems [62]. The experience of the National Institute for Occupational Safety and Health (NIOSH) has been similar, with roughly one-half of its indoor air quality investigations revealing a problem with inadequate ventilation [63,64]. 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 [62]. Improper maintenance of heating, ventilation, and air-conditioning systems contributes to an increased prevalence of symptoms among occupants and has been linked to outbreaks of legionellosis [36,65].
In a meta-analysis of six studies comparing symptoms in workers in mechanically ventilated air-conditioned buildings with workers in naturally ventilated buildings, there was a two- to threefold increase in the prevalence of work-related headaches, lethargy, and upper respiratory/mucous membrane symptoms in those working in mechanically ventilated buildings [66]. In one study comparing workers in a "sealed" office building with mechanical ventilation to workers in a naturally ventilated building, the overall prevalence of work-related symptoms was high among workers in both buildings and somewhat increased among workers in the mechanically ventilated building [67]. These symptoms include lethargy and headache in >50 percent of workers and breathlessness and chest tightness in about 20 percent. Other common symptoms included dry or itchy eyes and stuffy or runny nose.
Several studies have found an association between empirically increased ventilation rates and decreased symptoms, including headaches, respiratory symptoms, nose and throat symptoms, and skin complaints [68-71].
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. Indoor air concentrations of CO2 typically range between 500 and 1500 parts per million (ppm), while outdoor concentrations are generally 350 to 450 ppm [72]. A rough guideline is that CO2 concentrations should not exceed 1000 ppm in indoor environments for comfortable air quality [2,73,74]. However, CO2 is an imperfect measure, and low measured levels do not rule out inadequate ventilation throughout a building.
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 [72]. A rough guide is that ventilation rates at or below 10 L/second per occupant are associated with increased symptoms among building occupants [65]. However, some studies suggest that outdoor air supply rates as high as 25 L/second per person are necessary for health and comfort [65]. 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) [75].
Other variables — The proportion of fresh (outdoor) air versus recirculated air is also important. Low ventilation rates and high proportions of recirculated air have both been associated with exacerbating allergies [65].
Mechanical ventilation systems may include filters for particulate matter that can limit fine smoke particles, allergens, and other particles. Filter efficiencies vary, and filters must be maintained (cleaned or replaced) regularly to be effective.
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 [2,35,76]. One study found that maintaining a building temperature at the lower range of thermal comfort in the winter and the higher range of thermal comfort in the summer was associated with fewer symptoms [77]. The Occupational Safety and Health Administration (OSHA) recommends temperature control between 68 and 76°F [78]. ASHRAE recommends winter temperatures between 68 and 76°F and summer temperatures between 72.5 and 80°F, depending on the relative humidity (at higher humidity levels, recommended temperatures are at the lower end of the range) [74].
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 [79]. 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 [76]. OSHA recommends humidity control between 20 to 60 percent [78], and ASHRAE recommends humidity control between 30 to 60 percent [74] 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 exposures by generation of 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 [80]. 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 health building design focuses primarily on symptoms, comfort, and productivity [81,82]. Some studies have shown perceived improvements in respiratory symptoms and stress after green renovations of low-income housing [83] or moving the workspace from a conventional to a green office space [84,85]. 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 [86]. However, not all studies have demonstrated improvement in perceived occupant comfort or satisfaction [87]. In other studies, there were demonstrated improvements in health outcomes. As an example, 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 [88].
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 and asthma are more likely to report building-related symptoms [89]. The prevalence of asthma and atopy are continuing to increase among both children and adults [90]. Work-exacerbated asthma is common, with an estimated prevalence of >20 percent of adults with asthma [91]. It is notable that more than one-half of patients with work-related asthma work in nonindustrial settings such as office buildings, schools, and medical facilities [92,93].
Patients with atopy or asthma may be more likely to respond to irritants and allergens such as cleaning products and environmental tobacco smoke at levels found in nonindustrial settings [94,95]. Acute exposure to high levels of irritants (eg, a bleach spill in a hospital) is also more likely to cause significant symptoms in atopic individuals. Patients with atopy or allergy are also at higher risk of work-related rhinitis and contact dermatitis. Thus, the possibility of work-exacerbated symptoms in atopic or asthmatic patients should be carefully considered, and attempts to reduce or avoid problematic exposures is the cornerstone of management.
Psychosocial work factors — Work stress has been implicated as a potential cause of building-related complaints. The demand-control-support paradigm of psychosocial work factors has been used widely in occupational health, including in the study of building-related complaints. High work demand, low job control, and low support have been related to increased prevalence of building-related complaints [89,96]. More specifically, workers who perceive having too high a workload, low stimulation from their work, very little control over their work environment (including the physical environment), and little help from coworkers tend to have more symptoms related to indoor air and work environment [97]. This holds true across gender and age groups and regardless of smoking or atopy history, although different groups may perceive their workload or level of control and support differently [97]. Perhaps the best framework in which to consider psychosocial factors, including work stress, is as mediating and/or modifying factors that can increase vulnerability to environmental exposures [98].
Gender — Symptoms related to the indoor environment are reported more commonly by women [2,89,96,99]. This may be because of gender variations in work environment or work tasks, sensitivity to environmental factors, or a difference in rate of reporting [2,89,96]. There may also be an interaction between gender and work environment, particularly in jobs with low social support and lower control [89].
Other — A variety of other host factors have been studied, including age, educational level, and socioeconomic status. There is no consistent evidence linking these factors to symptoms in the indoor environment. These host factors are highly interrelated, and the relationships are complex and vary across industries and geographic populations. This may explain the lack of consistent results in the literature linking any one of these factors to building-related symptoms. Studies looking at such factors also tend to represent office workers or other narrow slices of the socioeconomic spectrum, making it difficult to draw broad conclusions.
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 clinical syndrome or disorder, such as asthma or rhinitis. Then, 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:
●Do the patient's symptoms suggest an identifiable disorder (eg, rhinitis, asthma, infection) or are they nonspecific?
●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 [100]:
●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?
A symptom diary can be a helpful adjuvant to the clinical history when there is a suspicion of building-related 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. It can be helpful to ask the patient to keep a diary documenting their symptoms in conjunction with 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 occupational and environmental health", section on 'Occupational and environmental 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.
Additional clinical evaluation and referral — Based on the history and physical findings, further testing may be warranted. As an example, if the history suggests asthma, workup may include spirometry with a bronchodilator response. Spirometry is widely available, although it may be normal when symptoms are not present. Serial peak flow measurements or other confirmatory testing can be useful in this setting. These data can also be useful in establishing an occupational relationship to symptoms. (See "Occupational asthma: Clinical features, evaluation, and diagnosis", section on 'Diagnosis'.)
●Although not always possible, in certain building-related illnesses, it is important to attempt to identify the specific causative exposure so that the patient can avoid further contact. Examples include hypersensitivity pneumonitis and work-related asthma caused by specific sensitizing agents. Identifying the causative agent is most likely to be successful if attempted prior to complete removal of the patient from the workplace. The generalist will usually need the help of a specialist, such as a pulmonary, allergy, or dermatology expert in these situations. (See 'Reporting' below.)
●If stress and/or psychosocial factors may be involved, referral to an appropriate counselor or therapist may be helpful.
The majority of building-related illnesses and symptoms are related to more than one exposure combined with inadequate ventilation. The generalist can effectively manage most of these situations using the modalities discussed below.
WORKPLACE EVALUATION — 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. Without the patient's permission, the clinician could contact the employer if they feel they can maintain patient privacy, but this can be difficult when discussing a specific work area or job description or in a small company. 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.
A more involved workplace evaluation is appropriate for patients with unusual specific exposures or if the patient's job may be at risk. Involvement of an occupational and environmental medicine practitioner is appropriate in these situations. In the United States, local consultants in environmental medicine can be found through the Association of Occupational and Environmental Clinics or the American College of Occupational and Environmental Medicine’s Doctor Finder tool.
A formal workplace evaluation will typically involve a team including a clinician, an industrial hygienist, and possibly a building and ventilation engineer. The initial step 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) [101]. 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) or specific bioaerosols.
Extensive air or surface sampling is rarely indicated and can be expensive and of little benefit. It is also rare that one single factor is identified, and often interventions to improve ventilation are helpful, even in the absence of any obvious etiologic factor [101]. 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. Allergens in particular are not harmful unless people are specifically sensitized and reactive to them. Thus, such sampling is most likely to be clinically helpful when the patient has symptoms consistent with immunoglobulin E (IgE)-mediated allergic disease (asthma, rhinoconjunctivitis) or a hypersensitivity disorder known to be related to a fungus. Not all molds or allergens can be accurately measured using the techniques available. Allergen and mold sampling are discussed in greater detail separately. (See "Allergen sampling in the environment" and "Assessment of mold in the indoor environment".)
DIAGNOSIS — Most patients with building-related symptoms have an underlying condition(s) such as rhinitis, allergic conjunctivitis, and/or asthma, in the authors' experience (table 1). The clinician should first attempt to clarify the patient's diagnosis(es). The following topics review the diagnosis of many of the common illnesses that are caused or exacerbated by workplace environments:
●(See "Allergic rhinitis: Clinical manifestations, epidemiology, and diagnosis".)
●(See "Chronic nonallergic rhinitis".)
●(See "Asthma in adolescents and adults: Evaluation and diagnosis".)
●(See "Common allergens in allergic contact dermatitis" and "Irritant contact dermatitis in adults".)
●(See "Hypersensitivity pneumonitis (extrinsic allergic alveolitis): Clinical manifestations and diagnosis" and "Hypersensitivity pneumonitis (extrinsic allergic alveolitis): Epidemiology, causes, and pathogenesis".)
Next, it may be possible for the generalist to determine whether the disorder is building related or non-building related, based upon available information and the clinical assessment.
●(See "Occupational rhinitis".)
●(See "Occupational asthma: Definitions, epidemiology, causes, and risk factors" and "Occupational asthma: Clinical features, evaluation, and diagnosis".)
●(See "Reactive airways dysfunction syndrome and irritant-induced asthma".)
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.
Worker's compensation in the United States — 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 illness 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. The employee usually initiates the workers' compensation process. The clinician's role is to provide documentation of the patient's medical condition when requested. Workers’ compensation benefits play an important role in ensuring that the patient is able to receive all required medical treatments and prescription medications, including in the event of financial hardship or changes in health insurance status should they occur in the future. (See "Disability assessment and determination in the United States", section on 'Workers' 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.
In a minority of building-related illnesses, 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 [102]. 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.
A sample communication is below:
●"(Patient name) is under my care. My medical evaluation suggests that there may be issues with the indoor air quality at their workplace. They may benefit from further assessment of indoor air quality or a change in work location.
Attention to indoor air quality can identify factors that could be modified to improve the workplace environment for your employees. Such factors typically include a combination of sources of exposure, such as dust, allergens, recent construction, or cleaning products, plus inadequate ventilation. Temperature or humidity levels may also contribute. Indoor air quality testing (eg, mold sampling) can be costly and is not recommended in most cases. Qualitative assessments of sources of exposure, ventilation, temperature, and humidity are usually successful in identifying issues that can be modified to improve the air quality for your employees. Input from employees can be helpful as well.
Thank you for your attention to this matter."
Most buildings will have a maintenance specialist who can help facilitate necessary assessments. Patients and employers who have additional questions about building assessments can be directed to their local health departments or the EPA [100,102]. (See 'Resources' below.)
Reporting — 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). (See "Disability assessment and determination in the United States", section on 'Workers' compensation'.)
Follow-up — It is important to make sure that the building-related illness or symptom is not worsening despite usual management and attempts to control exposures and/or improve indoor air quality. If the symptoms are not improving and a formal workplace evaluation was not performed initially, it may be indicated at this point. (See 'Workplace evaluation' above.)
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).
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 [103]. 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
●Building-related illnesses are disorders that are associated with a particular building or indoor environment and meet diagnostic 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. It is important for the clinician to recognize when symptoms are related to the patient's workplace, as these symptoms should be treated as occupational illnesses. (See 'Terminology' above.)
●Building-related illnesses and symptoms are common in nonindustrial environments, such as offices and schools. Precise estimates of prevalence are lacking. (See 'Epidemiology' above.)
●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.)
●Ventilation is the process of exchanging indoor with outdoor air to create a comfortable indoor environment. Ventilation-related problems account for as much as 60 percent of indoor air quality problems. (See 'Building factors' above.)
●The majority of building-related illnesses and symptoms represent responses to 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 'Host factors' above.)
●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. When a defined condition is not identified, empiric increases in ventilation rates can decrease a wide range of symptoms, including headaches, respiratory symptoms, nose and throat symptoms, and skin complaints. Clinicians can request that employers reduce exposures and optimize ventilation. (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.)
