What Is Sick Building Syndrome?
The term "sick building syndrome" (SBS) is used to describe situations in which building occupants experience acute health and comfort effects that appear to be linked to time spent in a building, but no specific illness or cause can be identified. The complaints of sick building syndrome may be localized in a particular room or zone, or they may be widespread throughout the building.
In contrast to sick building syndrome, the term "building related illness" (BRI) is used when symptoms of a diagnosable illness are identified and can be attributed directly to airborne building contaminants.
A 1984 World Health Organization Committee report suggested that up to 30 percent of new and remodeled buildings worldwide may be the subject of excessive complaints related to indoor air quality (IAQ). Often, this condition is temporary, but some buildings have long-term problems. Frequently, problems result when a building is operated or maintained in a manner that is inconsistent with its original design or prescribed operating procedures. Sometimes, indoor air problems are a result of poor building design or occupant activities.
Symptoms of Sick Building Syndrome
Sick building syndrome may be suspected if building occupants complain of symptoms associated with acute discomfort. Possible symptoms of sick building syndrome may include:
- Headache
- Eye, nose, or throat irritation
- Dry cough
- Dry or itchy skin
- Dizziness and nausea
- Difficulty in concentrating
- Fatigue
- Sensitivity to odors.
The cause of these and other sick building syndrome symptoms is not known. Most people with sick building syndrome report relief soon after leaving the building.
Sick Building Syndrome Versus Building Related Illness
In contrast to sick building syndrome, occupants with building related illness (BRI) may complain of symptoms such as:
- Cough
- Chest tightness
- Fever
- Chills
- Muscle aches.
Unlike sick building syndrome, for people with building related illness, the symptoms can be clinically defined and have clearly identifiable causes. Complainants may require prolonged recovery times after leaving the building.
It is important to note that complaints may result from other causes. These may include:
- An illness contracted outside the building
- Acute sensitivity (for example, allergies)
- Job-related stress or dissatisfaction
- Other psychosocial factors.
Nevertheless, studies show that symptoms may be caused or exacerbated by indoor air quality (IAQ)problems.
Causes of Sick Building Syndrome
There are several possible causes of (or contributing factors to) sick building syndrome. These possible causes of sick building syndrome may include:
- Inadequate ventilation
- Chemical contaminants from indoor sources
- Chemical contaminants from outdoor sources
- Biological contaminants.
Inadequate Ventilation
In the early and mid-1900s, building ventilation standards called for approximately 15 cubic feet per minute (cfm) of outside air for each building occupant, primarily to dilute and remove body odors. As a result of the 1973 oil embargo, however, national energy conservation measures called for a reduction in the amount of outdoor air provided for ventilation to 5 cfm per occupant.
In many cases, these reduced outdoor air ventilation rates were found to be inadequate to maintain the health and comfort of building occupants. Inadequate ventilation, which may also occur if heating, ventilating, and air conditioning (HVAC) systems do not effectively distribute air to people in the building, is thought to be an important factor in sick building syndrome. In an effort to achieve acceptable IAQ while minimizing energy consumption, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recently revised its ventilation standard to provide a minimum of 15 cfm of outdoor air per person (20 cfm per person in office spaces). Up to 60 cfm per person may be required in some spaces (such as smoking lounges), depending on the activities that normally occur in that space (see ASHRAE Standard 62-1989).
Chemical Contaminants From Indoor Sources
Most indoor air pollution comes from sources inside the building. For example, adhesives, carpeting, upholstery, manufactured wood products, copy machines, pesticides, and cleaning agents may emit volatile organic compounds (VOCs), including formaldehyde. Environmental tobacco smoke contributes high levels of VOCs, other toxic compounds, and particulate matter that can be inhaled.
Research shows that some VOCs can cause chronic and acute health effects (such as sick building syndrome) at high concentrations, and some are known carcinogens. Low to moderate levels of multiple VOCs may also produce acute reactions, such as sick building syndrome. Combustion products, such as carbon monoxide and nitrogen dioxide, as well as inhalable particles, can come from unvented kerosene and gas space heaters, woodstoves, fireplaces, and gas stoves.
Chemical Contaminants From Outdoor Sources
The outdoor air that enters a building can be a source of indoor air pollution. For example, pollutants from motor vehicle exhausts, plumbing vents, and building exhausts (such as bathrooms and kitchens) can enter the building through poorly located air intake vents, windows, and other openings. In addition, combustion products can enter a building from a nearby garage.
Biological Contaminants
Types of biological contaminants include:
- Bacteria
- Molds
- Pollen
- Viruses.
These contaminants may breed in stagnant water that has accumulated in ducts, humidifiers, and drain pans or where water has collected on ceiling tiles, carpeting, or insulation. Sometimes, insects or bird droppings can be a source of biological contaminants.
Physical symptoms related to biological contamination include:
- Cough
- Chest tightness
- Fever
- Chills
- Muscle aches
- Allergic responses (such as mucous membrane irritation and upper respiratory congestion).
One indoor bacterium, Legionella, has caused both Legionnaire's disease and Pontiac fever.
These elements may act in combination and may supplement other complaints, such as inadequate temperature, humidity, or lighting. Even after a building investigation, however, the specific causes of the complaints may remain unknown.
Sick Building Syndrome: A Word About Radon and Asbestos
Sick building syndrome is associated with acute or immediate health problems;
radon and
asbestos, on the other hand, cause long-term diseases which occur years after exposure, and, therefore, are not considered to be among the causes of sick building syndrome. This is not to say that the latter are not serious health risks; both should be included in any comprehensive evaluation of a building's IAQ.
Sick Building Syndrome and Building Investigation Procedures
The goal of a building investigation is to identify and solve indoor air quality complaints, such as sick building syndrome, in a way that prevents them from recurring and which avoids the creation of other problems. To achieve this goal, it is necessary for the investigator to:
- Discover whether a complaint is actually related to indoor air quality
- Identify the cause of the complaint
- Determine the most appropriate corrective actions.
An indoor air quality investigation procedure is best characterized as a cycle of information gathering, hypothesis formation, and hypothesis testing. It generally begins with a walkthrough inspection of the problem area to provide information about the four basic factors that influence indoor air quality:
- The occupants
- The HVAC system
- Possible pollutant pathways
- Possible contaminant sources.
Preparation for a walkthrough should include:
- Documenting easily obtainable information about the history of the building and of the complaints
- Identifying known HVAC zones and complaint areas
- Notifying occupants of the upcoming investigation
- Identifying key individuals needed for information and access.
The walkthrough itself entails visual inspection of critical building areas and consultation with occupants and staff.
The initial walkthrough should allow the investigator to develop some possible explanations for sick building syndrome. At this point, the investigator may have sufficient information to formulate a hypothesis, test the hypothesis, and see if the problem is solved. If it is, steps should be taken to ensure that sick building syndrome does not recur. However, if insufficient information is obtained from the walkthrough to construct a hypothesis, or if initial tests fail to reveal the problem, the investigator should move on to collect additional information to allow formulation of additional hypotheses. The process of formulating hypotheses, testing them, and evaluating them continues until the problem is solved.
Although air sampling for contaminants might seem to be the logical response to occupant complaints, it seldom provides information about possible causes of sick building syndrome. While certain basic measurements (for example, temperature, relative humidity, CO2, and air movement) can provide a useful "snapshot" of current building conditions, sampling for specific pollutant concentrations is often not required to solve the problem, and can even be misleading.
Contaminant concentration levels rarely exceed existing standards and guidelines, even when occupants continue to report sick building syndrome complaints. Air sampling should not be undertaken until considerable information on the factors listed above has been collected, and any sampling strategy should be based on a comprehensive understanding of how the building operates and the nature of the complaints.
Solutions to Sick Building Syndrome
Solutions to sick building syndrome usually include combinations of the following:
- Removing or modifying sources of pollution
- Increasing ventilation rates
- Air cleaning
- Education and communication.
Removing or Modifying Sources of Pollution
Removing or modifying the source of pollution is an effective approach to resolving sick building syndrome when sources are known and control is feasible. Examples include:
- Routine maintenance of HVAC systems (such as periodically cleaning or replacing filters)
- Replacement of water-stained ceiling tiles and carpeting
- Institution of smoking restrictions
- Venting contaminant source emissions to the outdoors
- Storage and use of paints, adhesives, solvents, and pesticides in well-ventilated areas, and use of these pollutant sources during periods of non-occupancy
- Allowing time for building materials in new or remodeled areas to off-gas pollutants before occupancy.
Several of these options may be exercised at one time as a sick building syndrome solution.
Increasing Ventilation Rates
Increasing ventilation rates and air distribution often can be a cost-effective means of reducing indoor pollutant levels. HVAC systems should be designed, at a minimum, to meet ventilation standards in local building codes; however, many systems are not operated or maintained to ensure that these design ventilation rates are provided. In many buildings, indoor air quality can be improved by operating the HVAC system to at least its design standard and to ASHRAE Standard 62-1989, if possible.
When there are strong pollutant sources, local exhaust ventilation may be appropriate to exhaust contaminated air directly from the building. Local exhaust ventilation is particularly recommended to remove pollutants that accumulate in specific areas, such as restrooms, copy rooms, and printing facilities.
Air Cleaning
Air cleaning as a sick building syndrome solution can be a useful adjunct to source control and ventilation, but has certain limitations. Particle control devices (such as the typical furnace filter) are inexpensive, but do not effectively capture small particles; high performance air filters capture the smaller, inhalable particles, but are relatively expensive to install and operate. Mechanical filters do not remove gaseous pollutants. Some specific gaseous pollutants may be removed by adsorbent beds, but these devices can be expensive and require frequent replacement of the adsorbent material. In sum, air cleaners can be useful, but have limited application for sick building syndrome.
Education and Communication
Education and communication are important elements in both remedial and preventive indoor air quality management programs. When building occupants, management, and maintenance personnel fully communicate and understand the causes and consequences of sick building syndrome, they can work together more effectively to prevent problems from occurring or to solve them if they do.
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