What is Sick Building Syndrome?
Sick building syndrome is a broad label that covers a range of symptoms thought to be triggered when the sufferer spends time in a particular building. Symptoms range from specific symptoms such as itchy eyes, skin rashes, and nasal allergy symptoms, to more vague symptoms such as fatigue, aches and pains, and sensitivity to odours.
The term "sick building syndrome", was first coined in the 1970s, and its recognition at this time may in part be attributable to the increasing presence of electronic equipment and other factors. It is used when the symptoms of a significant number of people occupying a particular building, are associated with their presence in that building. In most cases sick building syndrome occurs in office buildings, although it may also occur in other communal buildings such as schools and apartment buildings.
According to the US Environmental Protection Agency (EPA), sick building syndrome is strongly suspected when the following circumstances are present:
- Symptoms are temporally related to time spent in a particular building or part of a building
- Symptoms resolve when the individual is not in the building
- Symptoms recur seasonally (heating, cooling)
- Co-workers, peers have noted similar complaints
The circumstances most suggestive of sick building syndrome are presence of common symptoms amongst a group of building occupants that are present when they are in the building and absent when they are not in the building.
The EPA highlights the distinction between sick building syndrome and building related illness. The latter term is used for situations in which signs and symptoms of diagnosable illness are readily identified and can be attributed directly to specific airborne building contaminants. Examples of building related illnesses are Legionnaires' Disease and hypersensitivity pneumonitis. In contrast, the cause(s) of symptoms in cases of sick building syndrome are often hard to pin down and in many cases a range of factors may contribute to the situation. When a sick building is identified an extensive investigation by people such as the employer, building owner or manager, building investigation specialist, and if necessary, local medical authority epidemiologists and other public health officials, is often required.
Once a sick building has been investigated various measures must be taken to ensure the cause(s) are removed to make it safe for the occupants.
Although the problem of sick building syndrome has been recognized for decades, statistics regarding the prevalence of the problem are limited. A World Health Organization (WHO) report from 1984 suggested that up to 30% of new and renovated buildings worldwide may generate excessive complaints related to indoor air quality (1). This high rate may be associated with modern mass produced construction materials that tend to offgas irritating volatile organic chemicals (VOCs). In a US report, of office workers questioned at random, 24% reported air quality problems in their work place, and 20% believed this harmed their ability to do their job effectively (2).
Symptoms of Sick Building Syndrome
Sick building syndrome involves a variety of seemingly unrelated symptoms, much like other unexplained conditions such as chronic fatigue syndrome (CFS), and Gulf War syndrome (GWS) do. Some authorities have attempted to separate the symptoms into distinct categories such as 'allergic' and 'non-allergic', or 'chemical related' and 'microbe related'. Since there is yet no concensus on these distinctions, the common symptoms of SBS are listed here together:
- Eye, nose, and throat irritation
- Dry cough
- Dry, itchy skin, rashes
- Dizziness and nausea
- Difficulty in concentrating
- Sensitivity to odours
Sensitivity to odours is the definitive symptom of the related condition multiple chemical sensitivity (MCS). Both SBS and MCS are thought, at least in part, to be due to exposure to VOC's in the air.
Causes of Sick Building Syndrome
Although in many cases the exact mechanism by which a building, or substances within the building, are causing the occupants to become ill is unknown, the problem areas can usually be identified and remedial action taken.
In many SBS cases poor building design, maintenance, and/or operation of the structure's ventilation system may be at fault (3). The ventilation system in particular is often found to be at the heart of the problem, and can itself be a source of irritants. In addition, a poor ventilation system can result in a buildup of pollutants within the building, in which case the indoor environment can often have air quality much lower than the outdoor air, even in a heavily polluted city centre with it's clouds of vehicle exhaust and other pollutants. Interior design factors, such as the arrangement of individual offices and cubicles, may also interfere with efficient functioning of ventilation systems. Essentially poor office design and maintenance of the ventilation system can amplify the negative health effects of various factors, both biological and chemicals, that we'll discuss below.
It has also been suggested that very low levels of specific pollutants, such as VOCs, that are present inside a building may act synergistically, or at least in combination, to cause symptoms of illness. The chemical industry is not strictly regulated, with the majority of the many thousands of chemicals in everyday use having not been tested for health effects before their introduction. Chemicals have traditionally been thought to be toxic only above certain concentrations but scientists are now finding they often have health damaging effects at much lower levels, previously considered to be safe. In the case of small amounts of multiple different chemicals acting in combination to cause illness, there is virtually no research on this to refer to, so any effects are entirely unknown.
The symptoms of SBS are likely the result of a combination of factors. Many of the symptoms can be attributed either to the known toxic effects of high levels of certain chemicals. Other symptoms are typical of allergic reactions which could be triggered by various allergens in a building. Still other symptoms are very reminiscent of those experienced by sufferers of multiple chemical sensitivity and many of the indoor pollutants identified in sick buildings are also those said to cause symptoms in those suffering from MCS. It's likely that all of these mechanisms and associated pollutants are involved in SBS.
The following is a closer look at the various indoor pollutants that can contribute to making a building 'sick':
Various chemical pollutants that can affect the health of a building's occupants are produced when heating systems or gas fired appliances such as stoves are poorly maintained, and thus don't burn fuel efficiently, or don't vent exhaust correctly.
The main pollutants from this source are:
Carbon Monoxide (CO) - a gaseous asphyxiant, CO is known as the 'silent killer' as it is colourless and odourless. When it is breathed in CO binds to red blood cells preventing them from carrying oxygen and essentially suffocating the victim. Methylene Chloride may also breakdown to form Carbon Monoxide as well. Methylene Chloride is a common toxic solvent used in many products such as paint and paint strippers.
Sulphur Dioxide (SO2) - is a colourless gas with a strong odour like that of a struck match. Sulphur dioxide is an irritant to the respiratory system and exposure to high concentrations for short periods of time can constrict the blood vessels in the lungs and increase mucous flow, making breathing difficult. Those most at risk from these effects include children, the elderly, those with chronic lung disease, and asthmatics. Other harmful effects of SO2 include it's ability to impair the respiratory system's defenses against foreign particles and bacteria when chronically exposed to low concentrations, and enhance the harmful effects of ozone.
Nitrogen Dioxide (NO2) - is another toxic gas produced from combustion of fuels. It can be fatal in high concentrations, whilst lower levels, like SO2, act as irritants to lung tissue. Long term low level exposure can destroy lung tissue and lead to emphysema. Long term exposure also makes people more susceptible to respiratory infections such as pneumonia and influenza. The risk of ill-effect is greatest for the same groups most affected by SO2.
Volatile Organic Compounds (VOCs)
Volatile organic compounds are organic (carbon-based) compounds that evaporate at ambient temperatures within a building. VOCs can 'offgas' from building materials and much of the contents of most buildings. These compounds often have effects on health from irritating the eyes, nose, and throat, to causing breathing difficulties, to increasing the risk of developing cancer. An example of a VOC commonly present in indoor air is formaldehyde, which is also one of the most toxic being both a strong respiratory irritant, and carcinogen.
Building Construction - High levels of formaldehyde offgas from particle board. Modern buildings or buildings renovated with modern materials suffer the most from offgassing of VOCs due to the extensive use of particle board rather than solid wood or stone/brick for interior walls etc. Particle board is also often used in place of solid wood in modern furniture such as computer desks and shelving. Although a cheap alternative to other materials, particle board is a major source of VOCs due to the high content of powerful adhesives used in its manufacture. Formaldehyde and other VOCs offgas from particle board used in building construction and furniture for years, with the highest concentrations being generated in the first 6 months.
Carpeting is another major source of VOCs in many buildings since a large number of chemicals are used in their manufacture in the form of glues, backing materials, flame retardants, and dyes. The specific VOCs that offgas from new carpet include acetone, toluene, xylene, formaldehyde, and benzene derivatives. These chemicals are all known to cause irritation, effect breathing, and produce various neurological symptoms. Many of them are also potent carcinogens.
Finishes such as paints and varnishes can also increase the VOC content of a building or room. That fresh paint smell is the result of paints high content of VOCs in the form of solvents and binders. In the case of oil based paints, whose use if thankfully being reduced in indoor paints, the entire base of the paint is made up of VOCs. The US EPA has determined that the off-gassing from architectural coatings is estimated to account for about 9% of the VOC emissions from all consumer and commercial products. Many of the VOCs used in paints have ben banned or are being phased out as they are now recognized to be highly toxic and/or carcinogenic.
Chemicals Used Within A Building - The various chemical based products routinely used inside a building can be an equally large source of VOCs. Products that contain VOCs range from chemical products used to clean a building to marker pens and printer ink, common in an office or school environment.
Cleaning products contain a range of toxic VOCs including diethyl phthalate, found in a range of products, toluene, found in stain removers, and hexane/xylene, found in aerosol sprays. Diethyl Phthalate is a known endocrine disrupter (interferes with hormone activity), toluene is a known carcinogen (cancer causing agent) and can cause neurological problems, and finally both hexane and xylene can also damage the nervous system.
Marker pens are a particularly concentrated source of VOCs as their very strong smell indicates. Their chemical constituents include methyl ethyl ketone (MEK), toluene, and formaldehyde. The VOCs present in marker pens have various consequences for human health including neurological effects. Ink cartridges and toners used in printers also contain VOCs, albeit at less concentrated levels than marker pens.
Electronic equipment also offgases a large amount of VOCs. In an office full of computers, these essential pieces of equipment can be a substantial source of VOCs which offgas from materials such as flame retardants and various other chemicals used in their manufacture.
Besides the above there are many other sources of VOCs within the average office building or other communal building. These include air fresheners, personal care products such as deodorants and perfumes, and laundry detergent and fabric softener residues on the occupants clothing.
For a more detailed look at some of these VOC sources see our multiple chemical sensitivity (MCS) page.
Although much has been done to reduce or eliminate the use of heavy metals in buildings in over the past few decades, older buildings may still contain a significant amount of these highly toxic substances. Buildings built or extensively renovated after the early 90's in most developed countries are not likely to have a problem, but many buildings constructed before this time could pose a risk for heavy metal poisoning. The two most common heavy metals present in buildings are lead and mercury.
Indoor paint manufactured before 1990 and outdoor latex paint manufactured before 1991 may contain mercury, which was added to paint mainly to prevent build up of mold on walls, as mercury is an effective antifungal agent. Mercury can damage health in a number of ways, from impairing detoxification to causing serious neurological damage and birth defects. In fact, the mercury containing compound thimerosal was routinely added to vaccines to prevent contamination by fungi and bacteria until concern about its role in causing autism recently lead to its removal. Mercury may also be present in small amounts in computer and electronic equipment.
Lead is another common problem in older buildings because it was also added to paints until a couple of decades ago. Lead-based paint is still a major problem in older buildings particularly when the residues are disturbed and become airborne such as during renovation or construction projects. Like mercury, lead can cause severe neurological damage and a host of other problems.
Unless disturbed by renovation it's unlikely that heavy metals would be a major contributor to cases of sick building syndrome. For older buildings the risk is there however so must always be considered.
As well as the chemical pollutants described above, various biological contaminants often contribute to cases of sick building syndrome. In fact biological factors are reported to be behind the majority of cases. These biological pollutants can cause illness through three different mechanisms:
- Toxicosis - symptoms caused by toxins produced by micro-organisms e.g. mycotoxins produced by mold/fungi
There are many sources of biological pollution that can affect a building and many reasons why a building might become contaminated and cause illness in its occupants. The following are the main sources of this form of pollution:
Toxic Black Mold - is reported to be the leading cause of sick building syndrome and building related illness. Mold grows rapidly in warm and damp environments. If the indoor environment is too humid or if water damage occurs through leaks or rising damp, mold growth is very likely to occur.
Viruses & Bacteria - are common in every building, especially high occupancy buildings such as offices and schools. These micro-organisms can make a significant contribution to causing SBS. They become increasingly problematic if humidity levels are either too low or too high, as a result of how their growth is affected and the fact that our defenses against them are also affected by humidity levels.
Dust Mites - are highly allergenic and thrive on the constant supply of shed human skin cells that accumulate in carpeting, soft furnishings, and other areas. Like mold and bacteria, dust mites like the warm and relatively humid environment that we usually provide in our buildings.
Pollen - is another allergy causing substance that can accumulate in a building if proper ventilation and filtering is not maintained. Pollens from various trees and plants can be troublesome for a great number of people. Aside from being carried on breezes through open doors or windows, pollens can also be brought indoors on the occupants shoes and clothing.
Insect Body Parts - although not well known are especially potent allergens for some people. Cockroach allergens are particularly troublesome allergens and are commonly implicated as contributors to sick building syndrome. Usually become a problem only when sanitation is poor.
The above are collectively known as bioaerosols. The common definition of a bioaerosol is any extremely small living organism or fragment of living things suspended in the air. They cannot be seen without a magnifying glass or microscope. Of course when a large growth of mold occurs, it does then become visible to the naked eye.
Reasons For a Building Becoming Contaminated by Bioaerosols
The primary reason why bioaerosols become a major problem in buildings is the presence of damp in the buildings structure and/or a high level of humidity in the air. There are numerous reasons why such a situation could arise, some of the most common being:
- Water damage to homes from flooding or storm damage.
- Leaks in plumbing, roofs, or from air conditioners or HVAC systems.
- Condensation on central air pipes, HVAC components, or other cool surfaces where insulation may not be present, is insufficient, or has become damaged. Uninsulated air conditioning coils or pipes will "sweat" the most when hot humid air contacts them such as during warm months.
- Ice damming on building roofs which allows water to seep under shingles and through roof sheathing.
- Dehumidifiers and humidifiers.
- Moisture from unvented or poorly vented kitchens and bathrooms.
- Poor insulation causing drafts or the "chimney effect".
- Defective heating and air systems such as clogged condensation drain lines and full drip pans.
Hygiene and Cleaning
Poor sanitary and cleaning practices also contribute to a building becoming contaminated with bioaerosols. In a high occupancy building for example, germs from bathrooms can easily be spread to the rest of the building if they are not cleaned and disinfected both effectively and regularly. People not washing their hands after using the bathroom can also be a big problem.
Another problem is often inadequate or poorly maintained cleaning equipment. A poorly functioning vacuum cleaner for example can do more harm than good by spreading dust around rather than picking it up. As we have heard, dust is a breeding ground for micro-organisms like dust mites that cause allergies in many people. It may also contain other allergens such as pollens that have either blown into the building or been carried in by the occupants. Dust may also harbour disease causing bacteria and other unpleasant organisms. Efficient vacuum cleaners are thus essential pieces of equipment for avoiding a sick building. Models equipped with HEPA filters which remove even the tinniest particles are infinitely preferable.
Going back to chemical pollutants, growing research shows that chemicals, such as flame retardants that are commonly used in electrical equipment and on furniture, accumulate in dust. If a building is not kept free from dust by regular and effective cleaning, the amounts of chemicals present will only increase and pose an ever greater risk for the occupants health.
Other Factors That May Contribute to Sick Building Syndrome
Besides the more obvious chemical and biological pollutants that are commonly present in buildings and can lead to SBS, there are a number of more subtle factors that can also contribute, sometimes significantly. The most common of these are:
Fluorescent Lighting and Electrical Equipment - People commonly report feeling unwell after spending time in buildings lit entirely with fluorescent strip lighting. The flickering light is very harsh and tends to give even otherwise healthy people headaches and make them feel drained. Many people also complain of feeling unwell when they spend time close to computer screens and other electrical equipment. It has been suggested that high frequency electromagnetic fields (EMFs) which are generated by electrical equipment and a building's wiring can cause a host of unpleasant symptoms such as fatigue, headaches, and inability to concentrate. Electrical Hypersensitivity (EHS) is the term used to describe the condition in which people are made ill by electromagnetic radiation.
Temperature - Although many would dismiss the ambient temperature within a building as a minor consideration, an environment that is either too hot or too cold can have a major effect on how people feel. With extremes of temperature the body has to work hard to maintain its own internal temperature at the right level. With resources focused on this task people can quickly become tired and drained and experience a wide range of symptoms. If the temperature is too hot for prolonged periods for example, people can become dehydrated with potentially serious consequences for their health.
Humidity - again can put a strain on the body as it tries to maintain equilibrium. Like high temperature, a very humid environment can lead to dehydration and associated problems.
Noise - is an equally important factor. Too much noise can be draining and produce headaches and other symptoms. It also makes it hard to concentrate so impacts on the productivity of workers in an office for example.
Bad Office Design/Ergonomics - A badly designed workplace can cause numerous health problems. A cramped office with uncomfortable furniture can result in injuries such as those to the back as well as injuries such as repetitive strain injury (RSI) from repetitive tasks such as typing.
Stress - is another important consideration in an office building in particular. Stress can be caused by work pressures such as deadlines but also by all of the other factors we've discussed here that often relate to a building's design. Stress is a leading cause of absenteeism as it can result not only in psychological distress but also many physical ailments as well.
What Can be Done About Sick Building Syndrome?
If you and other people living or working in the same building experience health problems that seem to only be present when you are in that building, or at least get much worse, then it is reasonable to suspect sick building syndrome. You should report the situation to the landlord, office manger, or whomever is responsible for the building and ask them to have an inspection carried out. If they are unwilling to cooperate then you may have to get local authorities such as an environmental health agency involved.
After a thorough environmental health inspection is carried out on a building to determine possible causes for the occupants health complaints, there are many measures that can be taken to rectify the situation. A combination of some of the factors we've discussed above will usually be involved and all will have to be tackled. Measures taken may include an overhaul or replacement of the ventilation system, structural repairs to prevent leaks and damp, a review of chemicals used in the building, a review of cleaning practices, and professional mold removal.
The important thing is to take action to have a suspected sick building investigated as soon as possible as it is likely that the problem will only get worse if not addressed.
1. U.S. Environmental Protection Agency, Office of Air and Radiation. Indoor Air Facts No. 4: Sick Building Syndrome, revised, 1991.
2. Kreiss, Kathleen. "The Sick Building Syndrome: Where Is the Epidemiologic Basis? "American Journal of Public Health 1990; 80:1172-73.
3. A professional group, the American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE), has established standards of ventilation for the achievement of acceptable indoor air quality. These criteria do not have the force of law, are typically invoked only for new or renovated construction, and even when met do not assure comfortable and healthy air quality under all conditions and in all circumstances.
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